Biological Report 85(7.4)
June 1986
THE ECOLOGY OF REGULARLY FLOODED SALT MARSHES
OF NEW ENGLAND: A COMMUNITY PROFILE
John M. Teal
Senior Scientist
Woods Hole Oceanographic Institution
Woods Hole, MA 02543
Project Officers
Edward Pendleton
Wiley Kitchens
Martha W. Young
National Coastal Ecosystems Team
U.S. Fish and Wildlife Service
1010 Gause Boulevard
Slidell, LA 70458
Performed for
National Coastal Ecosystems Team
Division of Biological Services
Fish and Wildlife Service
U.S. Department of the Interior
Washington, DC 20240
DISCLAIMER
The mention of commercial product trade names in this report does not
constitute endorsement or recommendation for use by the Fish and Wildlife
Service, U.S. Department of the Interior.
The ecology of regularly flooded salt marshes of
New England.
(Hialugicdl report ; 85(7.4))
"i'erforrncd for National Coastal Ecosystems Team,
l?fvision of Biological Services, Fish and Wildlife
ScrvJcc, U.S. Department of the Interior."
tiJUnP 1986."
Supt. of Dots. no.: I 19.89/2:85(7.4)
1. Tidemarsh ecology--New England, I, National
Coastal Ecosystetns Team (U.S.) II. Title.
111. SerCes: Biological report (Washington, D.C.) ;
85-2.4.
~~~i~~4.~~~N4T4~~ lYB6
574.5'2636
86-600536
Ihi!, report should be cited as fallows:
leaf, J.M.
1 no1 and:
61 PP.
1986.
lhe ecology of regularly flooded salt marshes of New
a community profile.
U.S. Fish Wildl. Serv. Biol. Rep. 85(7,4),
PREFACE
Salt marshes, especially the muddy,
wet, intertidal portions of them that are
described in this report, have often been
considered wastelands--areas to be filled
to make useful land or to be dredged to
make useful water.
From the scientific
point of view, the past few decades of
research on salt marshes have provided a
much better basis for evaluating marshes
than before.
From the esthetic point of
view, we probably value little that has
not been appreciated for the last several
hundred years.
But esthetics usually do
not play a large part in decisions
regarding
the
preservation of
salt
marshes.
various possible forms, pointed out the
uncertainty of much of the data and the
limit of
our
understanding of
the
interactions between marshes and coastal
waters.
his
comment on
Note
the
inadvisability of trading "our credibility
for political advantage." It is all too
easy for a scientist, believing he has
achieved a new way of understanding some
natural phenomenon, to promote his idea
for some management purpose.
This has
certainly happened in relation to salt
marshes.
Both the need for_, and the lack
of need for, the preservation of marshes
have been supported on the basis of
incomplete understanding.
Energy flow in a salt marsh was
outlined twenty years ago (Teal 1962) in
an effort to put together everything then
known about the way the Georgia marsh
system functioned.
Energy transfer was
the descriptive tool.
Since everything
produced within the marsh was not consumed
there, the author concluded that some of
it must be exported and, as a result,
contribute to the support of consumer
organisms in the estuaries. This export,
which was called "outwelling," was also
proposed by others (see Odum 1980, Nixon
Teal's data were based
1980, Dow 1982).
on studies of the intertidal parts of the
salt marsh and the conclusion did not
really extend beyond the tidal creeks
The notion of
within the marsh itself.
salt marsh support of estuarine life was
widely accepted and became one of the
arguments for salt marsh preservation.
There are occasions when it is
necessary to act on the basis of lessthan-complete
information.
Scientists
should do their best to make the results
of their efforts available to those who
make decisions.
If scientists do not,
managers
will, as
they
must,
make
decisions based on whatever information
they have. Unfortunately, those decisions
may be based only on politics or outdated
knowledge.
Scientists should make the
best information available.
They should
remain
skeptical
about
own
their
conclusions.
They should be willing to
test their ideas repeatedly when the
opportunity arises.
They should not go
to the most conservative extreme and
never be willing to give an opinion
about the wisdom of some proposed action.
The difficulty lies in distinguishing
the best scientific judgment
between
of what the consequences of an action
will be,
and one's personal opinion
about the consequences of the action
based on extrapolation from scientific
knowledge.
In the past twenty years, a good deal
has been learned about the way salt
marshes function, but there is still a
vigorous controversy about the role of
marshes as supporters of production in the
Nixon
them.
with
waters
associated
(1980), in a detailed review of the
questions surrounding marsh export in its
This report was written to provide a
summary of the current state of scientific
knowledge about intertidal salt marshes.
iii
It has been restricted principally to New
England to concentrate on a specific
habitat type. Other intertidal salt marsh
regional types are detailed in other
This profile
reports in this series.
draws very heavily on the past 12 years of
research at Great Sippewissett Salt Marsh,
Falmouth, Massachusetts.
Scientists at
the Woods Hole Oceanographic Institution,
the Boston University Marine Program, and
the Marine Biological Laboratory have been
studying Great Sippewissett Salt Marsh
extensively since 1970; studies of this
and other local marshes done prior to 1970
are also included in this Community
Profile.
In this profile, the reader is led
through a general description of the
marsh, into a discussion of the organisms
that dwell there and their adaptations to
the environment.
Special attention is
given to the marsh plants, particularly
S artina alterniflora, since much of the
6$-% marsh 1 ooks and how it works
depend on this plant.
The production of
both plants and animals is discussed, as
well as what controls production rates.
Nutrient cycling, decomposition processes,
iV
export from the marsh to coastal waters,
and marsh values are all considered.
The author did not try to cover all
aspects of the ecology of salt marshes,
nor are those considered dealt with in
equal detail.
There is no exhaustive
literature review and no detailed list of
marsh species. The interested reader can
get a good idea of the birds that make use
of the salt marsh by referring to the
appendix on birds in the New England tidal
flats community profile of this series
(Whitlatch 1982).
Though one must use
appropriate reservations, it is safe to
say that most birds that use mudflats also
use the marsh open places. Those making
more specialized use of marshes, e.g., for
nesting, are mentioned in the text.
Comments concerning or requests for
this publication should be addressed to:
Information Transfer Specialist
National Coastal Ecosystems Team
U.S. Fish and Wildlife Service
NASA-Slide11 Computer Complex
1010 Gause Boulevard
Slidell, LA 70458.
CONTENTS
Page
PREFACE ................................................................ iii
FIGURES ................................................................ vii
TABLES ................................................................. viii
ix
CONVERSION TABLE .......................................................
X
ACKNOWLEDGMENTS ........................................................
CHAPTER 1. DEFINITION AND DISTRIBUTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.1. Definition .....................................................
General Description ............................................
Geographic Distribution
::23*
..........................................
1: 3.1. Worldwide
1.3.2. Distributibn';n.Ea;teFn'united'jtete;'::::::::::::::::::::
. .
CHAPTER 2. PHYSICAL ENVIRONMENT .......................................
2.1. Protective Barriers and Sediments ..............................
Tidal Circulation ..............................................
Chemical Environment ...........................................
;:::
CHAPTER
3.1.
3.1
3.2.
3.3.
3. MARSH FLORAS ...............................................
Higher Plants ..................................................
1. Physiological Adaptations ..................................
Salt Marsh Algae ...............................................
Bacteria and Fungi .............................................
11
11
12
14
16
CHAPTER 4. MARSH FAUNAS ...............................................
4.1. Organisms of Terrestrial Origin ................................
4.1.1. Insects and Spiders ........................................
4.1.2. Reptiles ...................................................
4.1.3. Birds and Mammals ..........................................
4.2. Organisms With Marine Origins ..................................
4.2.1. Invertebrates ..............................................
4.2.2. Fishes .....................................................
17
17
17
18
18
20
20
23
CHAPTER 5. SALT MARSH PROCESSES .......................................
5.1. Productivity ...................................................
5.1.1. Higher Plants ..............................................
5.1.2. Other Autotrophs ...........................................
5.2. Decomposition ..................................................
5.2.1. Aboveground ................................................
5.2.2. Belowground ................................................
5.3. Nutrient Cycling ...............................................
5.3.1. Nitrogen ...................................................
5.3.2. Phosphorus .................................................
5.3.3. Sulfur Cycle ...............................................
5.3.4. Carbon .....................................................
27
27
27
30
32
32
34
35
35
40
40
41
V
Page
.........
..........
6.2. Marsh Exports ....................................... .........
44
44
44
.........
.........
.........
.........
4";
47
48
CH A P T ER
6.1.
6.
SALT M A R S H VAl_UES
Values
A ND
I N T ER A CT I ON S
. . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3, Pollutants and Marshes ..............................
6.3.1. Heavy Metals ....................................
6.3.2. Organic Contaminants ............................
6.3.3. Nutrients .......................................
RIFERENCCS
............................................................
53
FIGURES
Page
Number
Great B a r n s t a b l e Marsh. Massachusetts . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Growth o f B a r n s t a b l e Great Marsh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sediment cores from Barn I s l a n d Marsh . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Experimental p l o t s a t Great Sippewissett S a l t Marsh . . . . . . . . . . . . . .
...........
..............................
.....
.......................
........
...............
Snow geese concentrated on a s a l t marsh . . . . . . . . . . . . . . . . . . . . . . . . . .
Canada geese l a n d i n g on a s a l t marsh . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Male f i d d l e r crab on s a l t marsh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D i s t r i b u t i o n o f s i l v e r s i d e s and mummichogs i n a t i d a l creek . . . . . .
Mummi chog . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Comparison o f r e s i d e n t and non-resident f i s h e s o f Great
S i p p e w i s s e t t S a l t Marsh i n summer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Biomass of S a r t i n a i n f e r t i l i z e d p l o t s . . . . . . . . . . . . . . . . . . . . . . . . . .
Redox p r o f i es ~n marsh sediments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
R e s u l t s of aboveground decomposition experiments a t Great
Sippewi s s e t t S a l t Marsh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Decay o f S a r t i n a i n d i f f e r e n t n i t r o g e n c o n d i t i o n s . . . . . . . . . . . . . . .
Diagram o n l t r o g e n f l u x e s between a s a l t marsh and
surroundings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Net exchanges o f i n o r g a n i c n i t r o g e n between Great
S i p p e w i s s e t t S a l t Marsh and Buzzards Bay and between t h e
bay and ground water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Comparison o f n i t r a t e i n p u t from ground water. n i t r a t e e x p o r t
by t i d e s . and grass deni t r i f i c a t i o n i n Great Sippewi s s e t t
S a l t Marsh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Be i a t o a growing a t t h e low edge o f the s a l t marsh . . . . . . . . . . . . . .
h j i c l e o f CO, p r o d u c t i o n and 0, r e s p i r a t i o n i n Great
S i p p e w i s s e t t S a l t Marsh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lead d i s t r i b u t i o n i n marsh cores . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D i s t r i b u t i o n o f f i d d l e r crabs i n experimental p l o t s r e c e i v i n g
sewage sludge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Nitrogen content o f S a r t i n a i n f e r t i l i z e d p l o t s . . . . . . . . .
Herbivorous i n s e c t a5%un ance on experimental marsh p l o t s .
Responses of two marsh grasses t o n i t r o g e n f e r t i l i z a t i o n .
Peak biomass o f S p a r t i n a i n marsh f e r t i 1i z a t i o n experiment
Changes i n vegetation w ~ t htime i n experimental marsh p l o t
f--
?-
vii
2
6
8
10
13
13
15
19
20
21
22
24
24
26
29
29
32
33
37
38
39
41
42
46
r n
TABLES
Number
Page
P
1
2
3
4
5
5
7
Acreage o f S a r t i n a a l t e r n i f l o r a marsh on A t l a n t i c
.............................................
seaboardby'*
4
F i s h e s i n h a b i t i n g Great Sippewissett S a l t Marsh . . . . . . . . . . . . . . . .
23
28
Above- and belowground p r o d u c t i v i t y i n S a r t i na . . . . . . . . . . . . . . . .
Production o f benthic algae i n A t l a n t i c coas s a l t marshes . . . . .
31
36
N i trogen budget f o r Great Sippewissett S a l t Marsh . . . . . . . . . . . . . .
37
Annual n i t r o g e n exchanges f o r Great Sippewissett S a l t Marsh . . . .
Comparison o f age and p r o p e r t i e s o f two northeast U.S.
s~ 1t marshes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
-ef
CONVERSION TABLE
Metric t o U.S. Customary
Mu1 tip1 y
inches
inches
mil 1 imeters (mn)
centimeters (an)
meters (m)
ki 1m e t e r s ( km)
square meters (m2)
square ki l a m e t e r s (km2)
h e c t a r e s (ha)
feet
m i l es
10.76
0.3861
2.471
0.00003527
0.03527
2.205
2205.0
1.102
3.968
1.8(OC} + 32
Celsius degrees
U.S.
ounces
ounces
pou nds
pounds
s h o r t tons
B r i t i s h thermal u n i t s
F a h r e n h e i t degrees
mil 1 i m e t e r s
centimeters
meters
meters
kil omcters
ki 1 meters
s q u a r e meters
square f e e t ( f t 2 )
acres
square miles ( m i
hectares
s q u a r e k i l ometers
1 iters
cubic m e t e r s
gal 1 ons (gal )
cubic f e e t ( f t 3 )
acre-feet
Fahrenheit d e g r e e s
acres
Customary to Metric
inches
inches
feet ( f t )
fa thoms
miles (mi)
nautical miles ( m i )
ounces (02)
pounds ( l b )
s h o r t tons ( t o n )
British thermal u n i t s (Btu)
square feet
square m i l e s
g a l 1 ons
c u b i c feet
acre- feet
l i t e r s (1)
cubic meters ( m 3 )
cubic meters
mill igrams [mg)
grams ( g )
kilograms (k )
metric tons ? t )
metric tons
ki 1ocal ories ( k c a l )
TO O b t a i n
!iY
cubic meters
25.35
0.4536
0.9072
0.2520
grams
k i 7 og rams
m e t r i c tons
k i 1 ocal o r i e s
Gel s i u s degrees
ACKNOWLEDGMENTS
I wish to thank a1 1 the collaborators
rho have worked on s a l t marshes w i t h me
over the 30 years that I have had t h a t
pleasure. These include s c i e n t i s t s , high
school through post-graduate students,
marsh landowners, and, occasional l y , even
developers who were considering f i 11i n g o r
dredging but wanted more information about
the consequences o f t h e i r actions before
they proceeded. I want t o thank my f e l low
workers from the Sapelo Island Marine
Institute of the University o f Georgia
where I got started with my career i n s a l t
marshes: L.R. Pomeroy, E.P. Odum, H.T.
Odum, H. Kale, and the l a t e R. J. Reynolds,
Jr. More recently, 1 am i n considerable
debt to the indiii'duals who have been a
part o f the Great Sippewissett S a l t Marsh
project at Woods Hole Oceanographic
Institution, Boston University Marine
Program, and Marine Biology Laboratory.
MY p r i n c i p a l p a r t n e r has been I. Valiela.
many o t h e r s have c o n t r i b u t e d t o l i s t
them a1 1 , b u t I would 1 i ke t o thank B,
Howes, J. Dacey, D. Goehri nger, A. Giblin,
R. Van E t t e n , C. Cogswell , N. B u t l e r , and
C . Werme. 1 a l s o want t o mention Dorothea
Gifford,
Andrew D i d d e l , and S a l t Pond
s a n c t u a r i e s , on whose marshlands most of
our r e s e a r c h on New England s a l t marshes
was done. I am g r a t e f u l t o t h e reviewers
of t h i s e f f o r t , e s p e c i a l l y Ralph Andrews,
and t o my e d i t o r Martha Young for her
understanding o f my d i f f i c u l t i e s and long,
a d v i c e - f i 1l e d
telephone
conversations,
Rob Brown and Penny H e r r i n g a t NCET
a s s i s t e d i n e d i t i n g and r e w r i t i n g the
manuscript. Keyboarding o f the manuscript
was done by D a i s y S i n g l e t o n and Sue
Frederickson.
Sue L a u r i tzen designed
t h e l a y o u t , and t h e l a y o u t was formatted
by Daisy S i n g l e t o n .
TOO
CHAPTER 1. DEFINITION AND DISTRIBUTION
1.1
DEFINITION
The r e g u l a r l y flooded t i d a l s a l t
marshes o f eastern North America are
almost e x c l u s i v e l y Spartina a l t e r n i f l o r a
marshes. These marshes are flooded by a l l
t i d e s under normal c o n d i t i o n s i n areas
w i t h semidiurnal t i d e s . They are flooded
by seawater o r water t h a t i s s u f f i c i e n t l y
s a l t y t o i n h i b i t arowth o f p l a n t s such as
o r reed, o r S c i r us
flooded mars es
make up t h e "low mar%hH; i n c o n t r a s t , t h e
"high
marsh"
comprises
infrequently
f l o o d e d S a r t i n a atens s a l t hay marshes
(Nixon 1 9 k n &a
t h e "high marsh"
i s covered by a stunted form o f 2.
a1t e r n i f 1ora r a t h e r than S. patens.
-fk
This p r o f i l e i s r e s t r i c t e d t o t h e low
marshes
in
New
England.
I
will
subsequently r e f e r t o these r e g u l a r l y
flooded t i d a l sal ine marshes dominated by
S p a r t i na a1 t e r n i f 1ora as " s a l t marshes. "
Under the F i s h and W i l d l i f e Service's
Wetland C l a s s i f i c a t i o n system (Cowardin e t
a l . 1979), these marshes would be classed
as i n the e s t u a r i n e system, t h e i n t e r t i d a l
subsystem, and t h e emergent class.
1.2
GENERAL DESCRIPTION
Regularly f 1ooded t i d a l s a l t marshes
a r e r e a d i l y recognizable a1 1 along t h e
east coast even from a distance o r from
t h e a i r . They are f l a t , grassy areas w i t h
meandering t i d a l creeks running through
them (Figure 1). They l i e behind some
s o r t o f b a r r i e r t h a t p r o t e c t s them from
t h e f u l l force o f t h e ocean's waves.
Numerous small ponds o r pannes occur
between t h e t i d a l creeks. The occurrence
and nature o f these ponds have been
g r e a t l y m o d i f i e d as a r e s u l t o f t h e
numerous, s t r a i g h t d i t c h e s dug t o c o n t r o l
s a l t marsh mosquitoes. Although many o r
most o f t h e d i t c h e s l i e i n the h i g h o r
i n f r e q u e n t l y flooded p a r t s o f t h e s a l t
marsh (Nixon 1982), they are also found i n
the low marsh.
On c l o s e r examination, other features
o f the t i d a l marsh are r e a d i l y apparent.
The marsh sediments are t y p i c a l l y , b u t n o t
always, muddy and s o f t , saturated w i t h
water,
and general l y h i g h l y reduced
( l a c k i n g i n oxygen o r o t h e r o x i d i z i n g
compounds and b l a c k i n c o l o r ) . They smell
o f s u l f i d e s and o t h e r v o l a t i l e s u l f u r
compounds when disturbed. A1though t h e r e
are undecomposed r o o t s and rhizomes w i t h i n
the mud, low marsh sediments are mostly
nonorganic and cannot be c l a s s i f i e d as
peat.
Spartina a1t e r n i f l o r a i s f r e q u e n t l y
d i v i d e d i n t o two forms. t a l l and s h o r t .
The t a l l form occurs aiong the banks of
t h e t i d a l creeks and on a c c r e t i n g areas
w i t h i n t h e marsh.
I n New England, t h e
t a l l form g e n e r a l l y reaches 1.25 t o 2 m i n
h e i g h t (Shea e t a l . 1975).
The stems are
t h i c k and widely spaced.
The s h o r t form
grows on the remaining marsh.
These
p l a n t s may be as s h o r t as 10 cm, have
t h i n n e r stems, and grow more densely
packed.
I n areas o f poorest growth, t h e
p l a n t s may be very t h i n , short, and w i d e l y
spaced.
Although t h e r e i s a continuous
gradation between t h e t a l l and s h o r t
forms, t h e t r a n s i t i o n between them i s
o f t e n dramatic i n t h a t i t takes p l a c e
w i t h i n a very s h o r t distance. Though t h i s
type o f s a l t marsh i s almost a n a t u r a l
monocul t u r e o f Spartina a1 t e r n i f l o r a , a
few o t h e r higher p l a n t s such as S a l i c o r n i a
(glassworts) a l s o occur.
Algae grow on
t h e sediment surface between t h e grass
stems, o f t e n i n s u f f i c i e n t abundance t o
c o l o r t h e surface.
There i s an abundance o f
common
to
these
marshes.
wildlife
Though
Figure 1.
Great Barnstable Marsh, Cape Cod, Massachusetts, w i t h t h e t y p i c a l
meandering t i d a l creeks and t h e b a r r i e r beach i n the background. Photo by J.M.
Teal , Woods Hole Oceanographic I n s t i t u t i o n .
r e l a t i v e l y few kinds o f i n s e c t s occur
h e r e , t h o s e species present can be v e r y
abundant, as i l l u s t r a t e d by t h e annoying
mosquitoes and greenhead f 1ies. Snai 1s,
c r a b s , amphipods, mussels, and, a t h i g h
t i d e , s m a l l f i s h e s are present i n l a r g e
numbers.
Wading
birds
are
often
conspicuous feeders on t h e f i s h and
i n v e r t e b r a t e s ; r a i 1s, wrens, and o t h e r
l e s s conspicuous b i r d s are a l s o common.
Canada geese may feed on t h e leaves o f
S a r t i n a and, i n w i n t e r , snow geese may
d
j rhizomes. Small mammals, mink,
o t t e r s , and raccoons come onto t h e low
marsh t o feed on grasses, i n v e r t e b r a t e s ,
Raccoons sometimes
and s m a l l f i s h e s .
b u i l d n e s t s i n t h e h i g h grass t o w a i t o u t
the high tide.
There
are
conspicuous seasonal
changes i n t h e . s a l t marshes.
I n the
n o r t h , w i n t e r t y p l c a l l ~b r i n g s a t h i c k i c e
cover t h a t i s moved by t h e h i g h e r t i d e s .
Occasionally, i c e f r o z e n f i r m l y t o t h e
u n d e r l y i n g marsh r i p s a chunk o f marsh up
when r i s i n g w i t h t h e t i d e and leaves i t
j y i n g on t h e marsh surface.
These
~ c e - r a f t e d chunks i n t e r r u p t t h e o t h e r w i s e
dead, frozen, 1 eve1 surface. Though b i r d s
may r e s t on the marsh i n w i n t e r ,
in
general, t h e r e i s 1i t t l e a c t i v i t y .
S p r i n g warming comes s l o w l y :
the
r e g u l a r i n u n d a t i o n by t h e more s l o w l y
warming ocean waters delays t h e g r e e n i n g
of
t h e marsh i n r e l a t i o n t o t h e
neighboring uplands. The mud s u r f a c e i s
f i r s t t o c o l o r as i t i s warmed by t h e sun
a t low t i d e and algae grow q u i c k l y enough
t o t a k e advantage o f t h e b r i e f warm
i n t e r v a l s between t i d e s .
When i n e a r l y
summer t h e marsh t u r n s b r i g h t green w i t h
grass, t h e a l g a l c o l o r fades, robbed o f
t h e necessary l i g h t by shading o f t h e
h i g h e r p l a n t s . The marsh i s a t i t s h e i g h t
o f a c t i v i t y a t t h i s t i m e . The mud s u r f a c e
shows s i g n s o f f e e d i n g b y t h e swarms o f
c r a b s , s n a i l s , worms, and i n s e c t s t h a t
make t h i s t h e i r home.
Swallows f e e d i n
t h e a i r and h a r r i e r s s a i l o v e r t h e grass
l o o k i n g f o r meadow mice which e a t t h e
s u c c u l e n t bases o f t h e grass.
By l a t e summer t h e t a l l e r S p a r t i n a
has f l o w e r e d and s e t seed. Leaf t i p s t u r n
y e l l o w f i r s t i n t h e s h o r t S p a r t i n a and
g r a d u a l l y t h e e n t i r e marsh t u r n s y e l l o w ,
t h e n brown. Cool i n g o f t h e mud i s delayed
b y t h e w a t e r , now warmer t h a n t h e l a n d .
M i g r a n t s h o r e b i r d s f e e d on t h e small
in v e r t e b r a t e s s t i 11 a c t i v e and p r e s e n t i n
1arge numbers as b i r d m i g r a t i o n reaches
i t s peak. B u t c o l d e v e n t u a l l y c l a i m s t h e
marsh which e n t e r s dormancy again.
To t h e s o u t h , one encounters more and
more
winter
activity.
In
Georgia,
S p a r t i n a b e g i n s t o send up new shoots as
soon as t h e o l d ones d i e a f t e r f l o w e r i n g ,
so t h a t a l t h o u g h t h e autumn marsh i s
golden w i t h dead leaves, a c l o s e r l o o k a t
t h e bases o f t h e grasses shows t h e
b e g i n n i n g o f n e x t y e a r ' s green.
I t does
n o t o r d i n a r i l y g e t c o l d enough t o k i l l
t h e s e shoots, a l t h o u g h m i l d f r e e z e s do
o c c u r a l o n g t h e Georgia coast.
1.3
GEOGRAPHIC DISTRIBUTION
1.3.1.
Worldwide
S p a r t i na a1 t e r n i f l o r a marshes a r e
found a l o n a t h e e a s t c o a s t o f N o r t h
America fr& t h e G u l f o f Mexico t o t h e
G u l f o f St. Lawrence, i n A r g e n t i n a , and i n
w e s t e r n Europe. T h e i r g r e a t e s t abundance
i s along the east coast o f the United
States.
Toward t h e t r o p i c s t h i s t y p e o f
s a l t marsh i s r e p l a c e d b y mangrove swamps.
N o r t h o f t h e G u l f o f S t . Lawrence o t h e r
s p e c i e s o f grasses, p r i n c i p a l l y P u c c i n e l 1 i a phryganodes , r e p 1ace 2. a1 t e r n i f 1ora.
The European S. a1 t e r n i f 1o r a marshes
a r e a t ~ o u t h a m p t o n , England and spots
a l o n g t h e French and n o r t h e r n Spanish
coasts.
Most o f t h e S p a r t i n a marshes i n
Europe a r e occupied b y t h e n a t i v e S.
maritima
( s o u t h e r n Engl and t o ~ o r o c c o > ,
o r b y t h e new species, 2. a n g l i c a .
Spartina anglica i s a f e r t i l e polyploid
p r o d u c t o f t h e i n f e r t i l e 2. t o w n s e n d i i
which, i n t u r n , arose as a n a t u r a l h y b r i d
S.
maritima
and
i n t r o d u c e d S.
of
a l t e r n i f l o r a i n t h e l a t e 1 9 t h c e n t u r y near
S o u t h a m ~ t o n (Ranwell
1972).
S~artina
a n g l i c a ' now 'forms s a l t marshe;
from
I r e l a n d and S c o t l a n d t o n o r t h w e s t Spain.
T h i s s p e c i e s i s s t i 11 s p r e a d i n g n a t u r a l l y
and b y human a c t i v i t y , t h u s c r e a t i n g new
marshes b o t h n a t u r a l l y and a r t i f i c i a l l y .
1.3.2.
D i s t r i b u t i o n i n Eastern United
States
The
northernmost
salt
marshes
c o n t a i n i n g 2. a1 t e r n i f l o r a a r e f o u n d i n
Newfoundland and a l o n a t h e n o r t h shore o f
Lwrence.
I n these
the Gulf o f St.
r e g i o n s , t h e c o a s t l i n e has had l i t t l e t i m e
since the r e t r e a t o f t h e l a s t continental
g l a c i e r t o accumulate sediments i n p r o t e c t e d areas t h a t c o u l d be t h e b a s i s f o r
t h e f o r m a t i o n o f s a l t marshes.
Most o f
t h e s a l t marshes i n t h e s e areas a r e l i t t l e
p o c k e t marshes t h a t f i l l t h e head o f a bay
o r f r i n g e t h e edge o f a t i d a l f l a t . There
are, however, a few n o t a b l e s a l t marshes
e a s t o f Yarmouth, and o c c a s i o n a l l y e l s e where, i n Nova S c o t i a . The marshes i n t h e
Bay o f Fundy a r e s p e c i a l e x c e p t i o n s . The
s e v e r a l bays a t t h e head o f t h e Bay of
Fundy l i e i n an e a s i l y eroded sedimentary
b a s i n and have v a s t s a l t marshes.
Large
areas o f t h e s e were d i k e d and c o n v e r t e d
i n t o hay f i e l d s i n t h e 1 8 t h c e n t u r y . Small
marshes a r e t h e r u l e f o r much o f t h e U.S.
c o a s t n o r t h o f Boston, Massachusetts,
a l t h o u g h t h e Scarboro marshes i n Maine,
Hampton marshes i n New Hampshire, and
P a r k e r R i v e r marshes i n Massachusetts a r e
extensive.
As one moves s o u t h i n t o t h e r e g i o n s
where t h e c o a s t i s o l d e r , s a l t marshes
occupy more and more o f t h e c o a s t l i n e .
There a r e f a i r l y e x t e n s i v e marshes i n
southern
New
England and
New York
a1 though t h e y have s u f f e r e d c o n s i d e r a b l e
destruction
over
the
years.
For
example, much o f t h e Back Bay r e g i o n
o f Boston was o r i g i n a l l y s a l t marsh
t h a t was f i l l e d i n t h e 1 9 t h c e n t u r y .
Large
parts
of
Kennedy
Airport
in
New York C i t y and Logan A i r p o r t i n
Boston were o r i g i n a l l y s a l t marshes t h a t
were b o t h dredged and f i l l e d t o c r e a t e
runways.
Farther south, marshes become more
extensive a l l along t h e coast and i n t h e
large,
drowned-val l e y estuaries
(the
Delaware and Chesapeake Bays).
Many of
the marshes along the m i d - A t l a n t i c coast
are f a i r l y brackish and have S a r t i n a
h
a l t e r n i f l o r a o n l y on t h e creek b
t h e s a l t i e r regions. The l a r g e s t o f the
South A t l a n t i c c o a s t a l marshes a r e i n
South C a r o l i n a and Georgia, where 68% o f
the e a s t c o a s t ' s r e g u l a r l y f l o o d e d S.
a1t e r n i f l o r a marshes occur (Table 1J.
3 a r t i n a a l t e r n i f l o r a remains t h e dominant
h k p l a n t u n t i l , i n F l o r i d a , mangrove
swamps g r a d u a l l y r e p l a c e s a l t marshes.
Table 1. The acreage o f Spartina a l t e r n i f l o r a marsh i n
t h e States of the A t l a n t i c seaboard (Spinner 1969).
State
Maine
New Hampshire
Massachusetts
Rhode I s l a n d
Connecticut
New York
New Jersey
Delaware
Maryland
Virginia
North Carol i n a
South Carol ina
Georgia
F l o r i d a east coast
Totals
Marsh area
Percent o f t o t a l
1,455
375
7,940
645
2,077
11,530
20,870
43,756
15,980
86,100
58,400
345,650
285,650
41,200
0.16%
0.04%
0.86%
0.07%
0.23%
1.25%
2.26%
4.75%
1.73%
9.34%
6.34%
37.50%
30.99%
4.47%
CHAPTER 2. PHYSICAL ENVIRONMENT
2.1 PROTECTlVE BARRIERS AND SEDIMENTS
S a l t marshes r e q u i r e muddy o r sandy
sediments i n areas which r e c e i v e t i d a l
f l u s h i n g , b u t which a r e p r o t e c t e d from t h e
f u l l f o r c e o f b r e a k i n g waves.
Although
o l d and compact marsh p e a t i s somewhat
r e s i s t a n t t o e r o s i o n by wave a c t i o n and i s
sometimes seen on beaches where o l d marsh
sediments a r e exposed by sand movements,
t h e f o r m a t i o n o f a marsh r e q u i r e s a
q u i e t e r environment f o r t h e accumulation
o f sediment and growth o f marsh p l a n t s .
Small marshes p r o t e c t e d b y r o c k y outcrops
o r headlands can be found i n Maine and t h e
Canadian M a r i t i m e s . By f a r , t h e m a j o r i t y
o f s a l t marshes a r e p r o t e c t e d by sand
s t r u c t u r e s , e. g. , b a r r i e r beaches and
R e d f i e l d (1972)
islands
and
spits.
illustrated
vividly
how
the
Great
B a r n s t a b l e Marsh grew through h i s t o r i c a l
time
and
how
sediments
and
peat
accumulated as sea l e v e l rose ( F i g u r e 2).
The b a r r i e r beach t h a t p r o t e c t s t h e marsh
grew o u t from one edge o f an i n d e n t a t i o n
i n the coast,
converting i t i n t o a
p r o t e c t e d bay now f i l l e d w i t h marsh. The
c l o s e c o n n e c t i o n between b a r r i e r f o r m a t i o n
and marsh e x i s t e n c e i s f u r t h e r shown by
t h e response o f Georgia marshes t o changes
i n t h e i r p r o t e c t i v e b a r r i e r s over t h e
recent
geological
past
(Pomeroy
and
W i e g e r t 1981).
Growth o f sandy b a r r i e r s s i n c e t h e
r e t r e a t o f c o n t i n e n t a l g l a c i e r s , coupled
w i t h changes i n sea l e v e l , has c r e a t e d
l a r g e areas i n which marshes have formed
over most o f t h e e a s t e r n U n i t e d States.
Sea l e v e l has been r i s i n g between 1 and 3
mm y r - I over t h e p a s t few thousand years.
(A d e t a i l e d d e s c r i p t i o n o f long- and
s h o r t - t e r m changes i n sea l e v e l and t h e i r
causes can be found i n Nixon 1982. ) The
marsh l e v e l keeps pace w i t h sea l e v e l r i s e
through b o t h t h e accumulation o f sediment
and, t o a l e s s e r e x t e n t , t h e accumulation
o f o r g a n i c m a t t e r . The sediment i s t r a n s p o r t e d t o t h e marsh by r i v e r s and c o a s t a l
c i r c u l a t i o n which b r i n g s marine sediment
i n t o e s t u a r i e s and she1 t e r e d embayments.
Water movement slows i n t h e p r o t e c t e d
areas; t h e f l o w has l e s s c a p a c i t y t o c a r r y
p a r t i c l e s which t h e n s e t t l e t o t h e bottom.
Thus,
t h e b a s i n becomes p r o g r e s s i v e l y
s h a l l o w e r u n t i l i t can be c o l o n i z e d b y
marsh p l a n t s . P l a n t stems f u r t h e r impede
f 1ow and c o n c e n t r a t e sediment accumulation
a l o n g t h e edge o f t h e marsh. T h i s process
leads t o h i g h e r e l e v a t i o n s ( o r levees)
a l o n g t h e marsh face and t h e edges o f
t i d a l creeks.
Such levees a r e q u i t e
e v i d e n t i n Georgia marshes.
Not o n l y do marshes expand i n t o t h e
e s t u a r y o r bay as a r e s u l t o f sediment
accumulation, b u t t h e y a1 so extend i n t o
t h e a d j a c e n t 1and as t h e sea l e v e l r i s e s .
The c e n t r a l p o r t i o n o f t h e marsh g e n e r a l l y
keeps pace w i t h s e a - l e v e l r i s e . Thus, t h e
p a r t s o f B a r n s t a b l e Marsh w i t h t h e deepest
p e a t a r e some d i s t a n c e from t h e p r e s e n t
landward edge.
A l l o f t h e area between
t h e deepest p e a t s and t h e p r e s e n t upland
r e p r e s e n t former l a n d now b u r i e d beneath
s a l t marsh.
I n many cases, a b a r r i e r
b u i l t a t t h e back end o f t h e marsh
p r e v e n t s marsh growth o v e r t h e upland. A
r a i l r o a d l i n e forms such a b a r r i e r i n
Great S i p p e w i s s e t t S a l t Marsh. A s i m i l a r
s i t u a t i o n e x i s t s f o r almost every s a l t
marsh i n an urban s e t t i n g .
I n most o f
these cases, as sea l e v e l r i s e s , t h e marsh
cannot extend o v e r t h e upland. Since t h e
b a r r i e r beach does move i n l a n d w i t h t h e
r i s i n g water, t h e marsh, i f i t has a1 ready
reached
the
inland
barrier,
gets
progressively smaller.
I n a c r e e k bank i n B a r n s t a b l e Marsh,
R e d f i e l d f o u n d a c a v i t y which h e l d a cache
o f cobbles.
He i n t e r p r e t e d t h i s as t h e
remains o f a small b o a t b a l l a s t e d w i t h
small stones t h a t had been abandoned on
t h e marsh s u r f a c e i n t h e 1 7 t h century.
The wood had r o t t e d , t h e marsh s u r f a c e had
r i s e n about 30 cm keeping up w i t h t h e
change i n sea l e v e l , b u t t h e stones
remained i n p l a c e .
ice.
The t i d e l i f t s t h e i c e and marsh
b l o c k , and c a r r i e s i t up o n t o some o t h e r
p a r t o f t h e s a l t marsh.
The r e s u l t i s
mounds o f S. a l t e r n i f l o r a s t i c k i n g above
t h e marsh s u r f a c e i n e i t h e r h i g h o r low
marsh. The S a r t i n a u s u a l l y d i e s and t h e
sediment moun+h- e ~ etr erodes o r becomes a
s i t e f o r t h e growth o f marsh edge p l a n t s
I t may t a k e several y e a r s
l i k e Iva.
b e f o r e t h e s p o t r e t u r n s t o i t s former
elevation.
As one would expect from t h e way
marshes grow, c o a r s e r sediments a r e found
a t t h e growing edges o f t h e marsh and on
the adjacent f l a t s , while f i n e r p a r t i c l e s
p e n e t r a t e f u r t h e r i n t o t h e grasses. T h i s
p i c t u r e v a r i e s depending on t h e p a r t i c u l a r
s i t e and i t s p r o x i m i t y t o t h e sediment
source. I n New England, t h e newly forming
p a r t s o f t h e marsh t y p i c a l l y have a sand
sediment which changes t o s i l t y muds
f u r t h e r i n t o t h e marsh.
F a r t h e r south,
where a more abundant sediment supply
comes down t h e r i v e r s , marsh s u b s t r a t e s
c o n t a i n l e s s sand and more s i l t s and
clays.
This general p a t t e r n i s m o d i f i e d
by processes, such as changes i n t h e
seaward b a r r i e r , t h a t m o b i l i z e sand and
a l l o w i t t o be c a r r i e d i n t o t h e marsh by
flood tides.
T h i s r e s u l t s i n sandy
sediments we1 1 w i t h i n t h e marsh.
Low spots can a l s o be found i n t h e
marsh.
These l o w spots, i f they become
permanently f i l l e d w i t h water, are c a l l e d
pannes.
Pannes may r e s u l t from h a v i n g
marsh growth occur a l l around a s p o t on a
t i d a l f l a t ( R e d f i e l d 1972). T h i s a r e a i s
i s o l a t e d from t h e sediment supply i n t h e
f l o o d i n g water by t h e s u r r o u n d i n g new
I t cannot f i l l w i t h sediment o r
marsh.
d r a i n , so i t remains below t h e l o c a l
s u r f a c e l e v e l , w a t e r - f i l l e d a l l t h e time.
Low spots on t h e marsh may a l s o be
a s s o c i a t e d w i t h patches o f wrack s t r a n d e d
on t h e marsh. The wrack covers and k i l l s
t h e grass and a low spot may r e s u l t .
Storms cause masses o f sand t o be
c a r r i e d over t h e b a r r i e r and onto t h e
marsh, where t h e sand may be d e p o s i t e d on
a l a r g e area o f marsh s u r f a c e ( c a l l e d a
washover).
Wind-blown sand can have a
similar result.
N i e r i n g e t a1 . (1977)
found t h a t severe storms o f t h e p a s t few
decades c o u l d be recognized i n Connecticut
marsh cores by t h e sand l a y e r s they
d e p o s i t e d ( F i g u r e 3). The sand l a y e r s on
t h e marsh surface were subsequently b u r i e d
as sea l e v e l and t h e marsh s u r f a c e rose.
2.2
TIDAL CIRCULATION
Marshes a r e f l o o d e d and d r a i n e d
through c h a r a c t e r i s t i c , meandering t i d a l
creeks. I n t h e process o f f o r m a t i o n , t h e
marshes f i l l up t h e basins i n which t h e y
form
and numerous t i d a l
creeks o f
s u f f i c i e n t s i z e always remain t o c a r r y t h e
t i d a l waters t h a t cover t h e marshes a t t h e
highest tides. This e q u i l i b r i u m c o n d i t i o n
i s m o d i f i e d as t h e creeks erode t h e
o u t s i d e back o f t h e i r bends,
while
d e p o s i t i n g sediments on t h e i n s i d e bank.
The p o s i t i o n s o f t h e creeks change
s l i g h t l y w i t h time,
b u t the
total
watercourse area, which i s determined by
t h e marsh e l e v a t i o n i n r e l a t i o n t o sea
l e v e l , remains a p p r o x i m a t e l y t h e same.
Marsh v e g e t a t i o n p l a y s a c o n s i d e r a b l e r o l e
i n s t a b i 1i z i n g t h e p o s i t i o n o f t h e creeks.
I n New England, sand i s a l s o c a r r i e d
o n t o t h e marsh s u r f a c e b y " i c e r a f t i n g . "
I c e r a f t i n g occurs when i c e forms on a
beach o r sand f l a t ; a subsequent h i g h t i d e
l i f t s t h e i c e mass i n c l u d i n g t h i s l a y e r o f
sand, and w i n d and c u r r e n t s c a r r y t h e mass
i n t o t h e marsh where i t becomes stranded.
On m e l t i n g , a l a y e r o f sand remains on t h e
marsh
surface,
raising
the
local
elevation.
The mosaic p a t t e r n o f t i n y
changes i n e l e v a t i o n and v e g e t a t i o n t h a t
can form t h e boundary between h i g h and low
marshes i s a t l e a s t p a r t l y formed i n t h i s
manner.
G a r o f a l o (1980) found t h a t t h e bank
o f a f r e s h w a t e r stream m i g r a t e d 0.32 m/yr,
w h i l e a comparable s a l t marsh stream
m i g r a t e d o n l y t w o - t h i r d s as much because
t h e p e a t sediment bound by t h e f i b r o u s
grass r o o t s r e s i s t e d e r o s i o n .
Another
i n d i c a t i o n of
the erosion p r o t e c t i o n
p r o v i d e d b y S p a r t i n a can be seen i n t h e
Pieces of low marsh can a l s o be
s t r a n d e d by i c e r a f t i n g .
T h i s can occur
when a b l o c k of marsh i s frozen i n t o t h e
7
MAJOR
COLOR
MAJOR
COLOR
- . IGE
CHAN
........-
VEGETATION
.............
+ Sand
0 0 - 9 5 % S. p a t e n s
5-10%
S. e l t e r n i f l o r a
..............
......
I
'
and
..............................
9 0 - 9 5 % D. s p i c a t a
1 - 5 % S. p a t e n s
1 - 5 % S. a l t e r n i f l o r a
I
...............
..............I
98% D. s p i c a t a
1 % S. p a t e n s
II
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
100% Phragmites
australis
BARN ISLAND + I
BARN ISLAND 4'3
FtfWr. 3.
3 ' 1
~ l ~ t t * )a t~: t, t ) i
'"J"
, \?I,
1
f ~ * o n sediments
l
o f Barn I s l a n d Marsh, Connecticut ( N i e r i n g e t
1 it^ t j t l c ~ dw~ ~i t h Panicurn (bottom l a y e r ) , probably on the edge o f t h e
~''PIN"P~ I Y typica1FiiZEfi grasses as sea l e v e l rose. A f t e r t h e 1938
'"''IJ
kdc
it.i7it'. q"'".*t"'
<
<{-*,?
'
'"''i'") d'
~ ~ j ~4 ~i s . i%,tJ,3
f ~{ F ~
k t h I:
the siip~~et.aostsand l a y e r , t h e v e g e t a t i o n changed again. The
dPPragmiter nlarsh i n b r a c k i s h water which was r e p l a c e d by
)<<)j(>
experimental o i 1ing o f Whi t t a k e r Creek
s a l t marsh i n Chesapeake Bay (Hershner and
Fake 1980). T h i s marsh was c l o s e d o f f by
n a t u r a l s p i t s vegetated w i t h marsh p l a n t s .
When t h e S p a r t i n a was k i l l e d on o i l e d
s i t e s , t h e s p i t s eroded on t h e i r exposed
sides, a l t h o u g h t h e r e were no e r o s i o n a l
changes i n t h e u n o i l e d s i t e s .
High t i d e does n o t n e c e s s a r i l y occur
a t t h e same t i m e n o r reach t h e same
a b s o l u t e h e i g h t above sea l e v e l i n a l l
p a r t s o f a g i v e n marsh. Water movement
i n t o l a r g e marshes i s slowed by bottom
f r i c t i o n so t h a t h i g h water a t t h e extreme
i n n e r p o r t i o n s o f t h e marsh may occur
hours l a t e r t h a n h i g h water a t t h e edge o f
t h e marsh and t h e sea.
The t i d a l range
may d i f f e r between t h e mouth and i n n e r
A s t r o n g wind
p a r t s o f a l a r g e marsh.
b l o w i n g i n t o a marsh may h o l d water i n ,
doing away w i t h normal l o w t i d e , w h i l e t h e
o p p o s i t e wind can depress t h e h e i g h t o f
h i g h water.
The enormous 7-m t i d e s o f
n o r t h e r n Maine a r e n a t u r a l l y 1ess m o d i f i e d
by wind t h a n t h e t i n y 30-40 cm t i d e s o f
t h e s o u t h shore o f Cape Cod. The l a t t e r
a r e o f t e n more c o n t r o l l e d by wind than
g r a v i t y . T y p i c a l l y , south o f Cape Cod t h e
t i d a l range i s about 1 m w h i l e n o r t h o f
t h e Cape i t i s about 3 m.
Freshwater may e n t e r a marsh through
r i v e r s o r streams f l o w i n g i n t o t h e upper
p o r t i o n s o f t h e marsh, o f t e n through a
f r e s h w a t e r marsh. I n many marshes, a t
l e a s t i n New England, t h e r e i s a l s o
s i g n i f i c a n t f r e s h w a t e r i n p u t i n t h e form
of
groundwater
entering
from
the
T h i s water e n t e r s
surround; ng up1 ands.
most r e a d i l y i n sandy p a r t s o f t h e marsh
(such as c r e e k bottoms).
2.3
CHEMICAL ENVIRONMENT
The chemical environment o f s a l t
marshes
is
dominated by t w i c e - d a i l y
f l o o d i n g w i t h seawater.
The envi ronment
i s s a l ine, even occasional l y hypersal ine,
so t h a t t h e h i g h e r p l a n t s ( t e r r e s t r i a l i n
o r i g i n ) must have mechanisms f o r d e a l i n g
w i t h b o t h t h e water s t r e s s o f t h e h i g h
osmotic p o t e n t i a l and t h e abundance o f
sodium c h l o r i d e and o t h e r major components
o f seawater.
Since p e r c o l a t i o n o f water
i n t o s a l t marsh sediments i s slow, t h e
i n t e r s t i t i a l s a l i n i t y changes l e s s r a p i d l y
than t h a t o f s u r f a c e water.
Therefore,
i n t e r s t i t i a l s a l i n i t y , t h e s a l i n i t y around
t h e p l a n t r o o t s , i s o f t e n n o t t h e same as
t h a t o f t h e water f l o o d i n g t h e marsh.
Sediment s a l in i t y i s a1 so changed b y
evapotranspiration.
Water
evaporates
from leaves and t h e marsh surface, b u t t h e
s a l t s s t a y behind, t h e r e b y i n c r e a s i n g t h e
soil salinity.
Sediment s a l i n i t y may be
reduced b y t h e i n f l u e n c e o f r a i n o r
groundwater.
T i d a l waters are t h e p r i n c i p a l source
o f p l a n t n u t r i e n t s s i n c e seawater c o n t a i n s
abundant suppl ies o f c a l c i um, p o t a s s i um,
magnesi um,
and
many
other
elements
e s s e n t i a l f o r p l a n t growth. N i t r o g e n and
phosphorus a r e exceptions; however, t h e y
are t h e elements which l i m i t p l a n t
p r o d u c t i o n i n t h e sea, and we w i l l
c o n s i d e r t h e i r r o l e i n marshes i n S e c t i o n
5.3.
C o n d i t i o n s i n t h e marsh sediments a r e
g r e a t l y i n f l u e n c e d by t h e abundance of
sulfate
in
seawater.
Under
anoxic
c o n d i t i o n s , t h e r e a r e some b a c t e r i a t h a t
use s u l f a t e as an e l e c t r o n a c c e p t o r ,
decompose o r g a n i c m a t t e r , and produce
sulfide.
The
resulting
sulfide
is
p r i m a r i l y r e s p o n s i b l e f o r t h e degree o f
r e d u c t i o n i n marsh sediments. S u l f i d e i s
h i g h l y t o x i c t o most organisms, so those
t h a t i n h a b i t marsh sediments must e i t h e r
deal w i t h i t o r a v o i d c o n t a c t w i t h it.
Metals, e s p e c i a l 1y i r o n , a r e a1 so abundant
i n marsh sediments, and much o f t h e
s u l f i d e ~ r o d u c e d i s bound up as metal
s u l f i d e s ' ( ~ i n g 1983; H o w a r t h ' a n d G i b l i n
1983).
Another major f a c t o r i n t h e chemical
environment o f marsh organisms i s t h e i r
exposure t o a i r and sometimes r a i n d u r i n g
low t i d e .
The h i g h e r p l a n t s , as f a r as
their
leaves
are
concerned,
are
t e r r e s t r i a l a t l o w t i d e . T h e i r leaves a r e
exposed t o a i r and s u b j e c t e d t o t h e same
c o n d i t i o n s o f l i g h t , d r y i n g , and C02
avai 1a b i 1it y as nearby up1 and grasses.
Marsh animals t h a t can b r e a t h e a i r have an
Gases, which
abundant oxygen supp.1 y.
d i f f u s e t e n thousand t i m e s more r a p i d l y i n
a i r than i n w a t e r , a r e much more a v a i l a b l e
i n t h e v e r y uppermost l a y e r o f t h e
sediments a t low t i d e than a t h i g h t i d e .
The e x t e n t t o which water d r a i n s from
sediments and i s replaced by a i r a t low
t i d e determines how much o f the upper
layer a1 ternates between a q u a t i c and
a e r i a l condi t i o n s .
The exposure o f t h e marsh surface t o
r a i n f a l l can r a p i d l y change t h e s a l i n i t y
both a t and below t h e surface.
The
freshwater can penetrate f u r t h e s t i n
openings such ds crab burrows along the
edges o f t h e creeks, These changes i n
oxyqcn and s a l i n i t y are some o f the
p r i n c i p a l stresses t o which many marsh
orqan isms must adapt.
The tlydroluyy o f s a l t marsh sediments
i s riut we1 I - s t u d i e d .
Hemond and Burke
(1981) measured t h e i n f il t r a t i o n o f about
1 cm o f water i n t o a marsh sediment as the
t i d e f l o o d e d , and an e x f i l t r a t i o n o f about
0 . 8 cm on t h e f o l lowing ebb t i d e . Hemond
( 1Y82) ha5 p r ~iminary
l
measurements o f
prc?ssuro cha~tges ill marsh sediments o f up
t o 10 cm H1,O wtiich d r i v e water movement
durinr] t i d a l
cycles
to
an extent
hy peat
porosity.
Large
t l c t t ~ r mnc*d
i
drnuulltLt o t wntet' evaporate from p l a n t s
whic:k drc cdvelr more important tltan the
t i tlrc
i11 c o n t r o l 1 ing water movement
tttrclucyl~mdrsh sedimerlts dur-ing the growing
Water
\t*a.+or~ (Udctay and Mowes 1984).
cnc,vrntt*nt i n t o n~dt.sti sediments corltrol s the
r-trlq~ly o f c f i s $ o l v ~ ~substances
i
(suck as
p lattl.
t l l l t ~ i ~ ' l t t $ ;t~\d sulfate) ;
water
tnuvrmrr~l crut o f marst1 sediments c o n t r o l s
thra stjl)ply
of
oxygen
to
sediment
(trt)dt\ i smc.. Hot 11 sit 1 t J te and oxygen are
i ftvn lvlarf i n t h4.s dccomyos i t ion cycle and
lurmdt iotl o f rlott>itus i n $ 8 I t marshes,
m,,irs4.1rri I r l dress of r i s i r l g sea
l y s terns, they
dnd m a t e r i a l s
- , o t t l c * r l t c ~ \t~dirnr~tlt%.Mat.shes a l s o serve
t r i l 1t.r t i b t . s t
totk n ~ d t t ~ t ' i d l bt t i a t a c t as
:vtllttlcarrt.. \ I \ tlit. w a t ~ r . IJieccls o f p l a s t i c
$ifrtl
<itIrt*~
rro11-tk&yt-,id,3bl
e
matepi a ] s
I
I
l i l t o ttlc svd
1 ect i1) ttle
if1 l f t
I l l ! ( * % ($1
~ t " i t k r o r ~ c ~ 1 ) marshes.
I',!i liit.+t>(', % i i i11 d\, hcl<$vy l ~ l e t asl and
!ti;dt
c t r ' t g r r l \ ~ ,,
that
d t ' ~ attached
to
/ ) ~ t . l l l(i.,
l
r!thpusited hy t i d a l waters o r
l l ~ i i f . t l i d i t - t i i l l y f t q n ~ t,hp a i r a l s o
tlmti i s t i i l ~ i t i l tlte mdr'sj) sut.face.
S a l t marshes,
then,
a r e systems
s u b j e c t t o b o t h marine and t e r r e s t r i a l
c o n d i t i o n s i n a f a i r l y r e g u l a r a1 t e r n a t i ng
fashion.
Marshes are we1 1-watered wi t h
seawater; t h e i r sediments a r e anoxic and
have an a c t i v e s u l f u r c y c l e .
A t Great Sippewissett S a l t Marsh i n
Massachusetts, b i o l o g i s t s from Woods H o l e
have been experimenting w i t h sal t marshes
since 1970, p r i n c i p a l l y by f e r t i l i z i n g
small marsh p l o t s and f o l l o w i n g t h e
consequences.
F i g u r e 4 shows t h e l a y o u t
o f t h e experiments and t h e l e v e l s and
The r e s t o f
types o f f e r t i l i z e r used.
t h i s r e p o r t concentrates h e a v i l y upon t h e
extensive Massachusetts d a t a t o h e l p
e l u c i d a t e how s a l t marshes f u n c t i o n ,
though s i m i l a r o r r e l a t e d experiments done
a t o t h e r places a r e a l s o drawn upon.
f t r ~ cA
r
.it r
drpu5 i iiolili 1
~ t tc t t r n ~ i i d t i ~t,uilt
bt3rfiinc11ts
it ~ v v i
DOSAGE OF SEWAGE
SLUDGE-BASED
F E R T I L I Z E R ON PLOTS
L F rr
loweat (8,,/m~lweek)
Hf
=
mlddla ( 2 5 g / m 2 1 w e a k )
XF
=
higheel 175 Q l m 2 1 w e s k )
-
IOm
,=
(-\
C
'
experimental
plots
cOntro'
Figure 4.
Layout o f t h e experimental
p l o t s a t Great Sippewissett S a l t Marsh
(from V a l i e l a e t a l . 1975).
CHAPTER 3.
3.1
MARSH FLORAS
HIGHER PLANTS
The s a l t marsh we a r e concerned w i t h
here i s a l m o s t a monoculture o f S p a r t i n a
alterniflora.
Since
this
plant
so
dominates t h e appearance and s t r u c t u r e o f
t h e marsh, we w i 11 spend c o n s i d e r a b l e
space d i s c u s s i n g what i s known o f i t s
ecology.
Any e n v i ronmental change t h a t
a f f e c t s t h e abundance and d i s t r i b u t i o n o f
S. a1 t e r n i f 1o r a w i 11 have a c o r r e s p o n d i n g
e f f e c t on t h e s a l t marsh.
underground
parts.
Unl ike f r e s h w a t e r
w e t l a n d p l a n t s , i t a l s o has a mechanism
f o r d e a l i n g w i t h s a l t s and t h e consequent
h i g h osmotic c o n c e n t r a t i o n i n t h e s o l u t i o n
I t belongs t o a group
around i t s r o o t s .
o f t r o p i c a l grasses c h a r a c t e r i z e d b y t h e
C-4 p h o t o s y n t h e t i c pathway. These p l a n t s
The p r i n c i p a l f e a t u r e s o f t h e p l a n t
cover a p p a r e n t t o t h e o b s e r v e r a r e t h e
v a r i a t i o n s i n h e i g h t , d e n s i t y , and c o l o r
o f t h e sward r a t h e r t h a n t h e presence o f
A few o t h e r
o t h e r s p e c i e s ( F i g u r e 5).
species can be f o u n d i n t h e low marsh,
however.
Sea 1avender (Limoni um nashi i)
i s t h e most common " o t h e r p l a n t " i n t h e
New England
l o w marsh.
There
are
(Sal i c o r n i a ) ,
occasional
glassworts
e s p e c i a l l y where t h e marsh has been
disturbed.
We have a l s o found o t h e r
p l a n t s growing i n the r e g u l a r l y flooded
i n t e r t i d a l areas:
seaside a s t e r ( A s t e r
t e n u i f o l ius);
s p i k e grass
(Distich1 i s
spicata); gerardia, a small p u r p l e flower
c a l l e d by i t s g e n e r i c name ( G e r a r d i a
(=Agal i n i s )
maritima),
that
is
s e m i p a r a s i t i c on marsh arass r o o t s ; s a l t
hay ' ( s p a r t i na patens); -and sand spurrey
(Spergul a r i a
marina).
But
these
"non-Spartina
a1 t e r n i f l o r a "
p l a n t s are
much more common o n t h e h i a h marsh t h a n i n
low marsh. Widgeongrass (Ruppia mari t i m a )
occurs i n p o o l s and creeks w i t h i n t h e low
marsh area, b u t t h e s e areas a r e n o t r e a l l y
a p a r t o f t h e r e g u l a r l y f l o o d e d marsh.
is
a
S p a r t i na
a1t e r n i f l o r a
rhizomatous, c o a r s e grass t h a t can grow t o
as much as 3 m i n h e i g h t and has a number
o f a d a p t a t i o n s f o r l i f e i n s a l t marshes.
i t has a
L i k e most w e t l a n d p l a n t s ,
mechanism f o r s u p p l y i n g oxygen t o i t s
Figure 5 . S p a r t i n a a1 t e r n i f l o r a g r o w i n g
on banks o f t i d a l creeks. Massachusetts.
J.M.
Teal,
Woods
Hole
Photo
by
Oceanographic I n s t i t u t i o n .
have m o d i f i e d t h e r e g u l a r p h o t o s y n t h e t i c
so t h a t t h e y can be
pathway (C-3)
e f f e c t i v e a t h i g h e r temperatures, h i g h e r
light
levels,
and
lower
C02
concentrations.
Because
of
these
m o d i f i c a t i o n s , t h e y a r e more p r o d u c t i v e i n
t r o p i c a l c o n d i t i o n s than t h e C-3 p l a n t s .
They a l s o do w e l l i n temperate summers.
The b e s t known example o f a C-4 p l a n t i s
c o r n (maize).
3.1.1.
P h y s i o l o g i c a l Adaptations
Water/sal t balance,
T e r r e s t r i a l and
marsh p l a n t s must m a i n t a i n c o n t a c t w i t h
t h e a i r , v i a stomata on t h e i r leaves, t o
These
o b t a i n C02 f o r photosynthesis.
openings expose m o i s t c e l l membranes t o
t h e a i r so t h a t p l a n t s l o s e water by
evaporation. This water must be replaced
from water surrounding t h e r o o t s . Water
l o s s through t h e leaves and replacement
through
the
roots
is
termed
" e v a p o t r a n s p i r a t i o n . " I n the case o f s a l t
marsh p l a n t s , the water surrounding t h e
r o o t s i s s a l i n e , which leads t o a problem
of m a i n t a i n i n g s a l t , as w e l l as water,
balance
.
The outermost c e l l s o f S p a r t i n a
p l a n t s are waterproof so t h a t water does
n o t e n t e r t h e p l a n t through leaves b u t
r a t h e r i s s u p p l i e d through the root/xylem
system. The s a l i n e water surrounding t h e
r o o t s has an osmotic pressure o f about -25
bars (about -25 atmospheres).
Therefore,
a p u l l o f about 25 atmospheres i s r e q u i r e d
t o p u l l water through t h e r o o t membranes
a g a i n s t t h e osmotic pressure o f t h e s o i l
water.
This
pull
is
supplied
by
evaporation a t t h e l e a f surface and i s
t r a n s m i t t e d along t h e columns o f water i n
t h e xylem system t o the r o o t s . Since t h e
water p o t e n t i a l i n a i r a t even 98%
humidity
is
less
than
-25
bars,
evaporation can e a s i l y p u l l water o u t o f
t h e p o r e s o l u t i o n , through the p l a n t , and
o u t i n t o t h e atmosphere.
A l l t h e p l a n t c e l l s are i n c o n t a c t
w i t h the i n t e r n a l water system and,
t h e r e f o r e , must have a lower osmotic
p o t e n t i a l t o m a i n t a i n p l a n t t u r g o r . Most
h i g h e r p l a n t s simply w i l t i n seawater:
because the osmotic p o t e n t i a l i s lower i n
t h e seawater than i n t h e c e l l s , water
moves o u t of the c e l l s and i n t o t h e
seawater producing a l o s s o f t u r g o r ,
Spartina
solves
this
accumulating s a l t s i n t h e
As a r e s u l t , t h e c e l l s can
i n t e r n a l pressure (turgor)
atmosphere p u l l g e n e r a t e d
system.
problem
by
c e l l vacuoles.
maintain t h e i r
a g a i n s t t h e 25
i n t h e xylem
The
r o o t membrane p r e f e r e n t i a l l y
admits water, b u t s m a l l amount o f s a l t s
a l s o pass i n t o t h e p l a n t .
Although a l l
d i s c r i m i nated
ions
in
saltwater
are
a g a i n s t , some e n t e r t h e p l a n t more r e a d i l y
than o t h e r s . McGovern e t a l . (1979) found
t h a t t h e r a t i o o f sodium t o p o t a s s i u m i n
t h e xylem f l u i d (Na/K = 18.8) i s s i m i l a r
t o t h a t i n seawater (Na/K = 27.7).
However, t h e r a t i o s f o r sodium t o s u l f a t e ,
c a l c i u m , and magnesium a r e g r e a t e r i n t h e
p l a n t t h a n i n seawater (Na/S04 = 62 and
4.0; Na/Ca = 410 and 26.5; Na/Mg = 7300
and 8.3
f o r S p a r t i n a and seawater,
r e s p e c t i v e l y ) (McGovern e t a1 . 1979). The
difference
between
these
plant
and
seawater r a t i o s r e s u l t s f r o m s e l e c t i v e
uptake o f i o n s b y t h e p l a n t .
Similar
d i s c r i m i n a t i o n among i o n s has been found
i n c u l t u r e s t u d i e s o f S p a r t i n a (Smart and
Barko 1980). Measurements o f t h e c h l o r i d e
c o n c e n t r a t i o n i n t h e xylem sap o f S p a r t i n a
i n d i c a t e i t makes up about 5% o f t h e
c o n c e n t r a t i o n i n t h e p o r e w a t e r around t h e
The f a c t t h a t
r o o t s (Teal, unpubl . d a t a ) .
c h l o r i d e i s t h e p r i n c i p a l a n i o n i n t h e sap
i n d i c a t e s a 20 t o 1 d i s c r i m i n a t i o n a g a i n s t
t h e sum of t h e c a t i o n s i n seawater.
Since s a l t s i n excess o f t h e p l a n t ' s
need e n t e r t h e p l a n t , a mechanism must
e x i s t t o eliminate the surplus.
Spartina
has s a l t glands on i t s l e a f s u r f a c e s t h a t
can s e c r e t e a c o n c e n t r a t e d s a l t s o l u t i o n .
The s e c r e t i o n t a k e s p l a c e a g a i n s t a v e r y
h i g h g r a d i e n t . We have found t h e s e c r e t e d
solution
to
be about 20
times
as
c o n c e n t r a t e d as t h e s o l u t i o n i n t h e xylem
(Teal e t a l . , unpubl. d a t a ) .
I n other
words, t h e p l a n t can l o s e 19 t i m e s more
water t h r o u g h t r a n s p i r a t i o n t h a n t h r o u g h
s e c r e t i o n and s t i l l m a i n t a i n i t s safe
balance.
The s e c r e t i o n i s 20 t i m e s more
c o n c e n t r a t e d t h a n t h e sap w h i c h i s 20
times l e s s c o n c e n t r a t e d t h a n t h e p o r e
water around t h e r o o t s .
Thus, t h e secret i o n i s a p p r o x i m a t e l y as s a l i n e as t h e
Pore water. When t h i s c o n c e n t r a t e d secret i o n i s exposed t o t h e a i r , i t t y p i c a l l y
d r i e s c o m p l e t e l y and forms s a l t c r y s t a l s
t h a t s p a r k l e i n t h e sun ( F i g u r e 6).
\
0%
I
RESPIRATION
I
Figure 7. R e s p i r a t i o n o f S p a r t i n a l e a v e s
grown a t d i f f e r e n t s a l i n i t i e s .
The d a t a
a r e f o r l e a v e s o f d i f f e r e n t ages, w i t h t h e
youngest 1eaves r e p r e s e n t e d by t h e t o p
1i n e (J. M. Teal , unpubl . data).
Figure 6.
S a l t c r y s t a l s on a l e a f o f
S p a r t i n a a1t e r n i f l o r a r e s u l t i n g f r o m t h e
d r y i n g o f s o l u t i o n secreted by t h e s a l t
glands on t h e leaves. Photo b y J.M. Teal,
Woods
Hole Oceanographic
Institution.
A l t h o u g h S p a r t i n a can e f f e c t i v e l y
deal
with
salts
a t normal
seawater
concentrations, there i s a l i m i t t o t h a t
tolerance.
As s a l in i t y i n c r e a s e s , t h e
p l a n t s e x h i b i t higher r e s p i r a t i o n r a t e s
(Figure
7)
and
reduced p r o d u c t i v i t y
( F i g u r e 8). Above s a l i n i t i e s o f 40-45 p p t
(parts
per
thousand),
the
increased
r e s p i r a t i o n and reduced g r o w t h become
p a r t i c u l a r l y obvious (Woodhouse e t a1 .
1972; Haines and Dunn 1976).
Survival a t
these e l e v a t e d s a l i n i t i e s decreases as
l e n g t h o f exposure increases.
S p a r t i n a depends on t h e i n t e g r i t y o f
i t s s a l t b a r r i e r t o maintain i t s s a l t
balance.
Damage t o t h e s a l t b a r r i e r
a l l o w s f u l l - s t r e n g t h seawater t o e n t e r t h e
p l a n t , d i s r u p t i n g t h e s a l t balance and
01
20
1
25
I
I
30 35
I
I
40
45
1
INTERSTITIAL SALINITY (Oioo)
Figure 8. Growth o f S p a r t i n a a1 t e r n i f 1o r a
a t v a r i o u s s a l i n i t i e s as measured by w e t
w e i g h t and by l e a f a r e a ( N e s t l e r 1977).
k i l l i n g the c e l l s .
Hence, t r a m p l i n g o r
d r i v i n g on t h e marsh, e s p e c i a l l y when
water i s present, r e s u l t s i n t h e death o f
the Spartina stems.
w
OX
en su
. Another problem t h a t
5 , a t e r n 1 era has i n r e l a t i o n t o i t s
F a b i t a t I $ t h a t sediments around i t s r o o t s
are t y p i c a l l y anoxic.
I t s roots, while
able t a e x i s t w i t h o u t oxygen f o r s h o r t
periods, must have oxygen f o r t h e i r
r e s p i r a t i o n f o r long-term s u r v i v a l . This
oxygen passes through a i r spaces t h a t are
continuous w i t h t h e stomata on the leaves.
through aerenchyma ( a i r passages) i n
leaves and stems, through the hollow
c e n t r a l $pace i n the rhizomes, t o the
c e n t r a l a i r space i n t h e r o o t s . A i r moves
by d i f f u s i o n through these spaces w i t h
s i r f f i r i c n t case t o supply the demands of
tttc itndcrgrour\d p a r t s o f the p l a n t s .
It
u s ~ d t o be thouyht t h a t t h i s f l u x was
s u f f i c i e r i l t o supply oxyqen t o the
%udlmclnt immediate] y surr-oundt ng the r o o t s
a s w e t i (Ieel and Kanwisher 1966).
More
rprtlnt work !Augqests t h a t w h i l e t h i s may
bra tr'ue i t ! d r d i f i e d sediments where the
r o t i t r Art-\ S I J ~ ~ O U I ~ by
~ O ~gases ( e . 9 . . a t
l o r trdir on ct'crek banks), i t i s n o t the
C A W
whwr t t t r r o o t s are surrounded by
watrr
aatur'3tc.d muds. Howes e t a l .
( I i i H 1 ) tidve htrt)(~castcd t h a t some o t h e r
oxidr%ntmay t ~ c b coming from the roots. An
ortidatrt ot \urne type i s expected because
1
r*oc$te*drp o f t e l l ~ u r r o u n d ~by
d a 1ayer
[sf
o x it! t l @ d i rnrr, and tlie s o i 1 redox
pOl~tlt
Wautlcl p r o d u c t i v e 5 a r t i n a i s
t\i(ll$@rahan Lhdt arour~d poor y growiflg
?&*tyl t ( b d ~ h l l ^ . h , ill ttlr'11, i 11 igher than
t h a t *In sedim~rtt*, w i ~ t t o t r t p l a r l t cover.
+-
l i t t l e doubt t h a t t h e
tr\\errldt
yt,teei, tr9drtsmit oxygen t o t h e
t o o t t f o r t h t r t r orlt 1'tts))i vation,
(ileason
dtttj 1 \c3mdrl ( IZWl) %tlowvci t h a t t h e oxygen
it i I
i tI
111
t ti? under.y~.ound p l a n t
patslsi uftic l t r ~ c * r l cftir~rty hiqh t i d e i n t h e
ilarii wttiLrt o x y ~ e fi0t11d
~
tmt t>e replenished
Ity c r ~ t i ~ ~e rl i .f t t i T h i o t t trclrn the a i r o r by
phrtlo*syltl.hes~s 1 hcy sticj!psted t h a t t h i s
t f t i c r t i d l oxyclerb stot'e helps t o s e t t h e
Irl*c*r* I r m t t a t w h ~ e h ttrp platits can grow
r f t ttw r n t r r t t d d l iontr.
fhe dyproximate
aid-trde l u r ~ r l l m i t of S . a l t e r n i f l o r a
xoJ
t
1
1 11
of -5.
a
t to
aric r u s s f LJ l ty rflvdde t t w recju]ularly f loaded
I ) - h r j b o f t t W s n i t m,4rsh c o u l d be explained
rn t h t s marrrirr
tl~ert.
iq,
I n h i g h l y reduced, w a t e r l o g g e d s o i l s ,
t h e a i r spaces a r e n o t s u f f i c i e n t t o
maintain
oxic
metabolism
in
S.
a l t e r n i f l o r a r o o t s . T h i s may be a r e a s o n
f o r small p l a n t s t a t u r e i n such s i t e s .
Mendelssohn e t a l . (1981) showed t h a t i n
the
more
oxidized
marsh
sediments,
Spartina r o o t s f u n c t i o n a e r o b i c a l l y m o s t
o f t h e time. When muds become a n o x i c , the
r o o t s produce malate as t h e p r o d u c t o f
t h e i r metabolism. Malate i s n o n - t o x i c a n d
can be accumulated i n t h e r o o t s w i t h o u t
damage,
but
this
metabolic
pathway
produces no n e t energy f o r t h e p l a n t . I n
h i g h l y reduced
sediments,
the
roots
develop a l c o h o l dehydrogenase and p r o d u c e
ethanol.
Though e t h a n o l i s t o x i c , i t s
p r o d u c t i o n does y i e l d energy f o r r o o t
growth and maintenance b u t a t l o w e r l e v e l s
than oxygen-supported r e s p i r a t i o n .
The
ethanol
produced
apparently
diffuses
through t h e sediments r e a d i l y enough so
t h a t i t may n o t a f f e c t t h e r o o t s . I n t h e
most waterlogged c o n d i t i o n s where t h i s
d i f f u s i o n i s reduced, t h e e t h a n o l t o x i c i t y
may c o n t r i b u t e t o t h e s t u n t e d c o n d i t i o n o f
Spartina.
Oxygen supply t o t h e r o o t s i s a l s o
i n t i m a t e l y connected w i t h t h e n i t r o g e n and
s u l f u r metabolism o f S p a r t i n a .
It i s ,
t h e r e f o r e , connected w i t h t h e c y c l e s o f
these elements i n the marsh system and
w i t h r e s i s t a n c e of S a r t i n a t o s o i l t o x i n s
(Mendelssohn e t a 1 . k
These p o i n t s
w i l l be addressed i n S e c t i o n 5.3.
3.2 SALT MARSH ALGAE
Both macro- and m i c r o s c o p i c a l g a e
l i v e on t h e s u r f a c e o f sediments i n t h e
s a l t marsh and a r e a t t a c h e d t o v e g e t a t i o n
and o t h e r marsh organisms ( F i g u r e 9 ) .
Ascophy 11urn nodosum ( k n o t t e d wrack) and
Fucus v e s i c u l o s u s ( r o c k w e e d ) grow a t t h e
lower edge o f t h e S. a l t e r n i f l o r a zone and
sometimes form f s r l v dense mats.
The
~ n t e r o m o rha
macroscopic
( h o l 1ow g r e e ~ r e ~ e d s ; ' g a ~ n d
,
l e t t u c e ) can be abundant, especi'ally e a r l y
i n summer. Codium f r a g i l e (green f l e e c e )
grows on s u i t a b l e s u b s t r a t e s such as
oyster shells.
Some o f these macroalgae
are very abundant a t times.
I n early
summer,
before much growth o f marsh
grasses a t Great Sippewi s s e t t S a l t Marsh,
Ascophyl lum nodosum may appear t o have a
4
Figure 9. Ascophyl l l r m nodosum ( k n o t t e d wrack) g r o w i n g a t t h e base o f S p a r t i n a stems
i n a creekbank marsh.
P h o t o by J.M. T e a l , Woods H o l e O c e a n o g r a p h i c I n s t i t u t i o n .
g r e a t e r biomass t h a n 5. a l t e r n i f l o r a .
No
good measure o f t h e p r o d u c t i o n of these
species
at
Great
Sippewissett
is
available.
Ascophyl lum does disappear
r a t h e r r a p i d l y i n spring, suggesting t h a t ,
a t the very least, i t i s c o n t r i b u t i n g t o
t h e d e t r i t u s food web on t h e marsh. There
i s abundant evidence t h a t t h e green algae
a r e p r e f e r r e d f o o d i t e m s f o r a ~ ~ m b eofr
d e t r ital-algal
f e e d e r s s u c h as s n a i l s
Ulva and Enteromor~ha
(Gieselman 1981).
a r e a l s o e a t e n by b x t a n d some ducks.
M i c r o s c o p i c a1 g a e - - m ~ ~ t l y diatoms,
and green and b l u e - g r e e n a1 gae ( t h e l a t t e r
now u s u a l l y c l a s s i f i e d as bacteria)--are
abundant on t h e s u r f a c e o f t h e s a l t marsh.
A l g a l mats may be t h e dominant
o n r e c e n t l y formed sand f l a t s that
subsequently
be
invaded
alterniflora.
These mats a r e even
abundant a t h i g h e r e l e v a t i o n s than in the
5.
15
r e g u l a r l y f 1ooded p a r t s of t h e marsh.
According t o B l u m (1968), t h e a l g a e found
under
creekbank
S p a r t i na
in
tall ,
Massachusetts
a r e m o s t l y diatoms.
The
s h o r t e r g r a s s f o r m supports f i l a m e n t o u s
types o f a v a r i e t y of a l g a l species:
on
t h e mud s u r f a c e a r e m o s t l y blue-green
t I a c t e r i a a n d g r o w i ng up t h e l o w e r p a r t s of
t h e g r a s s e s are t h e b l u e - g r e e n Symploca
In l a t e
and t h e c h r y s o p h y t e Vaucheria,
winter,
early
s p r i n g (Bl urn 1968), and
e a r l y s " ~ m e r , b e f o r e grass growth shades
the mud surf ace (Van R a a l t e e t a l . 1976),
there
are
conspicuous
blooms
of
greens and blue-greens on t h e
mud surface,
even u n d e r what w i l l b e t a l l
grassI n G e o r g i a , Pomeroy (1959) found
pennate
diatoms (but also other
such
as
green flagellates
and
lage1 la t @ s ) i n 1ow, wet sediments.
found especially i n l a t e
winter and e a r l y s p r i n g .
Some o f the blue-green b a c t e r i a are
especially s i g n i f i c a n t t o t h e function of
the
earsh since
the
heterocystous ,
f i laceentous blue-greens are responsible
f a r n i t r o g e n f i x a t i o n on the marsh
surface.
I n Massachusetts, where a l g a l
rrrsts dominate t h e marsh surface, Calothryx
i s the important genus. Under the grass,
5 t i onma i s responsible f o r most o f the
i&g
f i x a t~
i o n (Van Raalte e t a l .
3.3 BACfERlA AND FUNGI
An abundance o f b a c t e r i a f u n c t i o n i n
the
anokir muds and p l a y a very important
r a l s i n t h e s a i t marsh. They are respons i b l c fur processes varying from photosynt h e s i s t o v j r i a u s aspects of decomposit i o n , fungi are also a c t i v e i n decomposit i o n though t h e i r ecology i s much less
we1 l understaod. Because fungi are aerotr!c ~ ~ g 8 n J t . m ~t h. e i r a c t i v i t i e s are l i m trcd t o the surfacer layers o f the marsh.
t h e reducers
materials.
for
their
source
of
raw
a
yeast,
is
Pichia y a r t i n a e ,
r e p o r t e d t o be an abundant o r g a n i s m i n t h e
m i c r o f l o r a of
L o u i s i a n a s a l t marshes
(Meyers e t a l . 1975). I t i s e x t r e m e l y
common on t h e surface o f , and i n f l u i d f i l l e d c a v i t i e s w i t h i n stems o f ,
s.
alterniflora.
I t can s u r v i v e on ~ p a r t i n a
l i p i d s and has an a c t i v e B - g l u c o s i d a s e
system ( f o r h y d r o l y s i s o f sugars d e r i v e d
It p r o b a b l y makes i m from c e l l u l o s e ) .
p o r t a n t c o n t r i b u t i o n s t o marsh decomposit i o n processes once t h e c e l l u l o s e has been
i n i t i a l l y a t t a c k e d ( a process i n w h i c h
o t h e r f u n g i are a c t i v e ) . .
P i c h i a s p a r t i nae and a n o t h e r y e a s t
made u p
(Klu verom ces
drosophi larum)
over
-salt
marsh y e a s t s f o u n d by
Mevers e t a l .
(1973) i n u n d i s t u r b e d
~ G i s i a n a marshes.' ~ i c h i aohmeri became
one o f t h e most abundant y e a s t s i n a
Louisiana s a l t marsh as t h e r e s u l t o f
c o n t r o l l e d a d d i t i o n s o f o i 1 (Meyers e t a1 .
1973).
--
a number o f kinds of b a c t e r i a are
ithurrcirrtt r*trurtgti f n s a l t marshes t o be
visrbir t o ttte naked eye
masse. For
Species of t h e y e a s t Candida a r e
ts~nrnplc, thr* I ' P ~ p h o t ~ s ~ ns ut l h
f u r~ ~ s i g n i f i c a n t
contributors
to
oil
h a ~ t r t ' i n trrrm layers j u s t
under the
degradation i n e a s t c o a s t s a l t marshes.
~ u r f a c a uhar* they are protected from
<Jky@?t%, which rmifion~,them, but where they
3 t l y e t ct\uuc)t~ l iqht t o photosynthesize.
i h r ~ r rat1 ptqmr~r\t*~are o f t e n v i s i b l e on
Meyers 1974). E r g o t , which i s r e s p o n s i b l e
ttro s t r r f - t c ~ crf slrttd layers;, b u t they are
f o r poisoning o f rye f l o u r , i s w i d e l y
a l . , ~ r present and v i s i b l e w i t h c a r e f u l
d i s t r i b u t e d i n s a l t marshes, b u t may be o f
vrsmrrret )an
i n muddy
areas.
These
1i t t l e e c o l o g i c a l s i g n i f i c a n c e t h e r e .
vtrgdtil;rnqs ~ f h l ) t o ~ ; y ~ t t hu~~~i fi lzg~H25 as a
Though marsh f u n g i a r e i m p o r t a n t i n t h e
t o u r c r i$.,I hyfjri%yta~jt a r reducing power.
formation of d e t r i t u s from S p a r t i n a (J.
t!rcv rrrc8rlucra 5u11 ttr as a byproduct.
Hobbie,
Marine B i o l o g i c a l
Laboratory,
tltf"*:*fi l x i i ~ f l t s rjse 1.$,0 drld pt'uduce oxygen. )
unpubl. data),
t h e y need more s t u d y .
f h r l u i f u r u%rdizers are a t t e n seen as a
w
*stit?r trtt I h c mdr+c~h strrface. The
I n t h i s r e p o r t , most o f t h e i m p o r t a n t
J
yrdfjuipi
i " @ ~ t l l t i n ~ fj r o m
the
microbes
in
the
marsh
system
are
"&1'9*'?0ft
0
'
a r v % t a r e d w i t h i n the
i d e n t i f i e d by t h e i r f u n c t i o n s ,
To a
'*'I5
at5fl @f,*oilb
the microbes.
considerable e x t e n t t h i s has been done
even by m i c r o b i o l o g i s t s i n t h e p a s t .
It
O~ljglaloil t s n common qellus t h a t
i s now known t h a t even some of t h e
$letl % f a r ,
t rom o x i d i r ing reduced
apparent 1y compact groups a r e r e a l 1y
%
1
#at t c r t,) t h d t reduce s u l f a t e ar-e
microbes
of w i d e l y d i f f e r i n g a n c e s t r y .
5
?.dtt
rndrst~es and
are
Some of these groups a r e r e s p o n s i b l e f o r
4 %jrhfrn 1 ip. nut tcf>d b e c d ~ ~ tof:
! t f l e smel 1
deni t r i f i c a t i o n , n i t r i f i c a t i o n , n i t r o g e n
of
41.5 I t l e v pvoduce.
These are n o t
f i x a t i o n , and methane p r o d u c t i o n .
The
~ ~ ~ +l* k ift @ii i livr.
i ~ the q r f l e r a l black c o l o r
l
a
r
g
e
s
t
f
u
n
c
t
i
o
n
a
l
group,
"decomposers
,"
1%
""'5"
%eiltmetlt5 t o wl,jch they
i s even l e s s u n i f i e d f o r i t i n c l u d e s most
:
+ J
*
t r r i a that o x i d i r e s u ] f i d e
non-photosynthetic
and
-chemosynthetic
dr
$1
3% hkift-()yen source
depend on
microbes.
f
"'
CHAPTER 4. MARSH FAUNAS
4.1 ORGANISMS OF TERRESTRIAL ORIGIN
4.1.1.
Insects
and
greater increases in the initially less
abundant
species,
i.e.,
mirids,
cicadellids,
grasshoppers.
and
The
fertilization increased the nitrogen in
the grass, making it a more suitable
substrate.
turn,
This,
in
led
to
increased fecundity and survival in the
Migration into the experimental
insects.
area was of secondary importance (Vince
1979).
Presumably, this equal abundance
and distribution
occur
naturally in
Droductive
creekbank
stands
of
S.
alterniflora.
Vince
(1979)
believes
that the non-creekbank marsh is barely
adequate for the maintenance of some
herbivorous
of
the
insects.
rarer
Stiling et al.
(1982) have found that
leaf-miners in
Florida are nitrogenlimited as are the herbivorous insects
mentioned above.
Spiders
Although there are many kinds of
insects on salt marshes, they are mostly
confined to the higher elevations.
Those
significant to
ecology of
the
the
reqularly flooded portions include those
that feed on Spartina alterniflora, some
that are associated with detritus, and
No group is
some that are predators.
represented by a large number of species.
Vince (1979) divided the insect
in Great Sippewissett Salt
herbivores
Marsh into chewers and sap-suckers.
The
lonq-horned
the
dominant
chewer is
grasshopper,
Conoce halus spartinae, but
and crickets are
thrips (Anaphothrips
sp.
+
Sucking insects are much
also present.
include plant bugs
more *abundant and
(Miridae, Trigonotylus sp.), plant hoppers
(Delphacidae,
Prokelisia marginata, and
Graminella
nigrifrons),
Cicadellidae,
The latter two
aphids, and scale insects.
types of insects are patchily distributed:
rare on another leaf of the same plant and
They may be
absent a few meters away.
locally abundant enough to kill blades of
Patches of scale insects may occur
grass.
30 cm below the level of barnacles growing
on Spartina, which indicates they are well
adapted to immersion in saltwater (Tippins
Prokelisia marginata
and Beshear 1971).
is the numerically dominant herbivorous
It also
insect (by orders of magnitude).
has 10 times more biomass/m2 than any
other species.
Some insects live within, rather than
the Spartina stems. ’ These are
usually larvae rather than adults.
For
example, larvae of otitid flies (genus
Chaetopsis) live within Spartina stems
where thev eat and kill the terminal bud,
thereby causing the death of the shoot:
The ecology of such insects is poorly
Studies in Florida
known in New England.
indicate that the otitid larvae reduce
competition in their limited environment
by stabbing and killing other larvae they
and Strong 1983).
encounter
(Stiling
represents a
the dead
larva
Though
valuable source of protein, the body is
not eaten; i.e., they are murderers rather
than predators.
upon,
Other insects found in the low marsh
chloropids,
dolichopodids, and
include
ephydrids.
These are all flies that feed
on a variety of plant secretions, algae,
and detritus both as adults and as larvae.
Biting midges and horse flies (such as the
infamous "green head") live in the mud as
larvae; as adults, the females attack
In fertilized experimental plots in
the Cape Cod marshes, the herbivorous
more
equitably
become
insects
have
differences
’
(smaller
distributed
between
t2
individuals
numbers of
prior
to
than
different
species)
There were
relatively
fertilization.
17
people and large animals to obtain the
blood meal they need to mature their eggs.
Aedes
mosquito,
marsh
The
lays
its
eggs
on
wet
mud
ln
sollicitans,
the hig he r marsh rather than in the low
The eggs develop to the hatching
marsh.
point, then wait until they are flooded by
an extra high tide or heavy rain before
In warm weather they can become
hatchiny.
adults "in about one week, emerging from
Were the eggs laid
the pools in hordes.
in the low marsh, the eggs (or larvae)
would be rapidly eaten by the predators
Even
that come in on the high tide.
though the low marsh iS not involved in
mosquito reproduction, it has been heavily
ditched TO P- "mosquito control.' The marsh
often suffers heavily from damage during
ditching and from careless disposal of the
The effects on
$poi Is from the ditches.
the mosquitoes are minimal.
prey both visually and tactilely instead
Pardosa prey upon
of building a web.
marsh amphipods about their own size,
which they flip over and bite on their
less-protected underside.
Another spider, Clubiona maritima,
also hunts, but moves much more slowly and
detects its prey by touch. Though spiders
the tide
climb Spartina as
sometimes
they
can
survive
underwater.
Their
rises,
greatest need at high tide is a refuge
from predators.
4.1.2.
Reptiles
Reptiles, such as sea turtles and
marine crocodiles, can be fully adapted to
Although the author has seen
seawater.
alligators, rattlesnakes, and water snakes
in salt marshes of the southeastern U.S.,
the only reptile seen in any great numbers
in New England salt marshes is the
(Malaclemys
terrapin
diamond-backed
common in
terrapin).
The
terrapin,
unpolluted waters all along the Atlantic
coast south of Cape Cod, is not a "sea
turtle" but is more closely related to the
It feeds on a
terrestrial box turtles.
variety of small animals including fish,
mollusks, and crustaceans abundant in the
marsh creeks,
The terrapin does not live
on the low marsh but feeds there during
low tide.
Terrapins used to be much more
abundant
than at
present,
but their
population
reduced
was
coastal
by
development and by hunting during the
height of their popularity as a food item.
Irwcts are preadapted to survival in
the marsh.
lhrir impermeable exoskeleton
evolved to prevent drying on land, and
al*,0 prevent.5 water loss to seawater or
entry of <ld 1 I.5
into the body.
Their
P#Xrt'tion
ot
Wa ste
nitrogen as
water-%,tving uric acid reduces their need
tar W*~IC~f, Fo many can survive on plant
j u i c, e s 0 f the body fluids ot p r e y ,
Some
avoid submersion by walking up the grass
c)t' flyin!) at hiyh tide, but others can sit
it but and I;urv\ve underwater.
4.1.3.
Birds and Mammals
One of the most widely recognized
values of salt marshes is their support of
both
migrant
and
resident
bird
populations.
Very
few
bird
species
actually
nest in
regularly
flooded
marshes.
Those that do include clapper
rails (Rallus longirostris) (Figure lo>,
willets *_(Catoptrophorus
long-billed
marsh
boat-tailed
arackles
2 major), red-winged blackbirds
(Age!aius phoenic Zeus), and sharptailed and
seaside sparrows Tmmospiza caudacuta and
A. maritima).
The larger insect herbivores (such as
plnnt hugs) in New England salt marshes
are eaten mainly by the large wolf spider
Pardusa
_r___-_i_. distincta
Pardosa actively bun;
-."-.""-"___-l
The number of species that nest in
drier areas but feed on the low marsh or
18
various terns dive from the air above.
Though most of the feeding activity is in
the creeks adjacent to the grassy parts of
the marsh, it is nevertheless connected to
the functioning of the marsh.
Exceptionally high tides in autumn
occasionally force insects to the tops of
the Spartina, and many kinds of birds,
from sparrows and warblers to terns and
gulls, come to feed on this bonanza of
Swallows capture flying
exposed insects.
insects in the air above the marsh much as
Birds are
they do over upland meadows.
like insects, adapted to marsh living by
their water-saving uric acid excretion and
by orbital glands which secrete excess
salt from their blood.
Mammals
constitute a smaller and
generally less conspicuous part of the
marsh fauna.
The most abundant marsh
mammal in New England is the meadow mouse
or vole, Microtus pennsylvanicus.
In the
high marsh, where meadow mouse runs are
obvious beneath the grass, the mouse is a
more conspicuous resident.
Although the
meadow mouse's feeding is restricted to
low tide in the low marsh, the large
fraction of plants damaged by the mice
indicates that the Microtus is a significant part of the marsh system. The damage
to the sward by the meadow mouse is far
greater than the actual consumption of
Spartina.
Microtus cuts off the base of a
plant and eats a small portion of the
tender basal part; the rest of the stem is
left to wither and die.
Under natural
conditions
on Great Sippewissett Salt
Marsh, about 7% of the short S. alterniflora plants show signs of insect damage
whereas about 2.5% show damage by mice.
In the fertilized plots where Spartina
productivity is
enhanced,
the insect
damage drops to about 5%, but 20%-30% of
the plants are damaged by mice (Vince
1979; Valiela and Teal, unpubl. data).
Thus, under these conditions, Microtus can
have a significant effect on Spartina
production.
rail
Clapper
(Rallus
Figure 10.
longirostris) standing on the high marsh
area at Great Sippewissett Salt Marsh,
Clapper rails feed on
Massachusetts.
animals of the intertidal salt marsh and
Photo
may also nest in its upper edges.
by J.M. T e a l , Woods Hole Oceanographic
Institution.
make seasonal use of it is much larger.
Dabbling ducks of various kinds sieve
from
animals
the
and
small
seeds
In winter, black ducks (Anas
sediments.
rubripes) feed extensively on the salt
marsh, especially at high tide when they
pluck the snail Melampus from the grass.
Snow geese (Chen caerulescens) eat roots
and rhizomes of the grass (Figure 11);
Canada geese (Branta canadensis) graze on
Many kinds of
(Figure 12).
Spartina
shorebirds probe for invertebrates (insect
larvae, mollusks, crustacea, and worms) in
Herons, egrets,
the more open areas.
stalk fishes
and
ibis
and
bitterns,
crustaceans along the creeks and in the
kingfishers, and
while ospreys,
ponds
(Peromyscus
mice
White-footed
primarily
seed
are
leucopus),
which
eaters, occasionally come down into the
In the marshes of the southern
low marsh.
United States, the rice rat, Oryzomys
palustris, is a permanent resident in tall
Small mammals such as
Spartina areas.
19
Figurs 11.
Snow geese concentrated on a salt marsh.
U.S. Fish and Wildlife Service.
Photo by Rex Schmidt; courtesy
their urine, their need for freshwater to
wash out sa It acquired in their diet is
reduced.
4.2 ORGANI!3MS
4.2.1.
WITH
MARINE
ORIGINS
Invertebrates
Most of the low marsh fauna are
invertebrates.
The larger ones have been
fairly well-studied, the smaller much less
so.
Meiofauna.
Benthic
meiofaunal
animals are defined operationally by their
ability to pass through a 0.5- or 0.3-mm
mesh.
They
include
such groups as
nematodes,
foraminiferans,
harpacticoid
copepods, soil mites, and oligochaetes
Many of these organisms are abundant i;
marsh sediments.
For example, Teal and
y'$;;; (13%) found nematodes numbering
and weighing 7.6 g in Georgia
marsh soils. Similar numbers of nematodes
have been found in marsh soils of south
M~~~~~~ of the marsh avoid getting
wet for the most part.
Some, like mice,
are
adapted to
the
high
salinity
~;~V~~~~~~~~~
Of the salt marsh.
Because
Alice can concentrate and expel salt in
20
-
Figure 12.
Canada geese (Branta canadensis) landing on a marsh.
This species eats
leaves of Spartina alterniflora, especially those in the more productive parts of the
marsh.
In New England, Canada geese may nest on salt marshes and, therefore,
concentrate their feeding on marshes during the nesting season.
Photo by Rex Schmidt;
courtesy U.S. Fish and Wildlife Service.
Carolina (Sikora et al. 1977) and Great
Foreman,
Boston
Sippewissett
(K.
University Marine Program, Woods Hole,
Mass., pers. comm.). The numbers of soil
foraminiferans are comparable to those of
but the other groups are
nematodes,
generally less abundant.
Water flooding the marsh at high tide
contains many planktonic forms.
Many of
these come from the coastal waters and/or
estuaries associated with the marshes. In
addition, some of the planktonic animals
come from the marsh itself.
These are
primarily eggs and larvae of marsh inhabAdult benthic meiofauna may also
itants.
be dislodged and suspended in the flooding
All forms of plankton are food for
water.
filter feeders on the marsh or for
plankton-feeding fish which advance into
the marsh on the flooding tide. Plankton
leaving on the ebb tide are a food source
for filter feeders in channels, on mudflats, and in the estuary proper.
21
Macrofauna.
The
typical
marsh
and
invertebrates--the
best
studied
probably the most
important to
the
functioning of the intertidal marsh--are
Their definition is
the
macrofauna.
complementary to that of the meiofauna:
they are retained on a 0.5-mm sieve. The
epibenthic fauna (those living above the
bottom) are the most familiar even though
the infauna (those living within the mud)
are usually more abundant.
Two species of fiddler crabs, Uca
pugnax (Figure lx
pugilator
and U.
are abundant south of Cape Cod, where
there can be 120 individuals/m 2 a l o n g
the creek banks (Krebs and Valiela 1977).
Mud crabs (Panopeus sp.), marsh crabs
(Sesarma reticulatum), and green crabs
(Carcinus maenas) make very conspicuous
holes at the edges of marsh creeks.
(Callinectes
sapidus),
Blue
crabs
where abundant, are important predators
on other marsh animals.
They occur as
far north as Massachusetts Bay though
they are usually seen only south of Cape
Cod.
at
common
the
littorea,
Littorina
is
a
common
marsh
resident
in
periwinkle,
New England, but in Maryland marshes it is
replaced by L. irrorata (gulf periwinkle).
Littorina ob'tusata occurs near the lower
edge of the marsh among the rockweeds with
associated.
commonly
which it is
Melampus bidentatus (salt marsh snail) iS
a pulmonate snail on the marsh. All these
snails feed by scraping off the surface
layer of algae and detritus from the
surface of the mud and from the lower
The tiny snail
parts of the grass.
!~~ totteni, which feeds by digesting
organic matter and microbes from ingested
sediment (Newell 1965), may be very
(Ilyanassa
Mud
snails
~~)~lr~d~nt.
@soletus)
are
more
typical
of
intertidal
WVm\mats, but they do occur in the marshes
ds well, where they feed mostly on benthic
algae (Conner 1980).
between the grass
Stems
u n d e r
esP@cially
wrack-
a n y
septemspinosus)
and the grass shrimp
(Palaemonetes
Pugio),
driftingup even the smallest marsh creeks
as the tide rises.
Although the above organisms are all
epifauna, many more organisms are found
among the infauna in this same environThe marsh infauna includes a
ment.
oligochaetes,
variety of polychaetes,
and
larvae),
insects
(especially as
crustaceans, but little is known about
most of these. As one moves south of New
England, other species join or replace the
Among these are the marsh
marsh fauna.
clam (Polymesoda caroliniana), the wharf
crab (Sesarma cinereum), the brown shrimp
(Penaeus aztecnd the white shrimp
(-if- all of which use the
and
sF;allow
marshes
waters of
the
estuaries.
Other species, such as the
blue crab, become more abundant south.of
New England; the blue crab can support an
intense fishery in the marsh creeks along
the southern Atlantic coast.
Bibbed mussels, Geukensia (=Modiolus)
demiss:!, throughout
often live in clusters
wlll,-“l^--..
h? f~%rsh and serve as hard substrate for
0thE?P erganisms such as barnacles and
Macrobenthic organisms play a number
of important roles in the functioning of
the salt marsh. They churn up the surface
layers of the sediment in their search for
food and in their burrowing.
(1980)
f
o
u
n
d
that the burro
a density of 42 animals/m2 turned over 18%
of the upper 15 cm of sediment per year.
Their burrows increased the surface area
of the marsh by 59%.
et al. (1980)
showed that the epifaunal fiddler crabs
and marsh periwinkles in a North Carolina
marsh consumed an amount of organic matter
equivalent to about one-third of the net
production of
2.
~~~ut~ $3. Male fiddl er
crab,{= pugnax)
on 5alt. marsh.
lhis ciao has beer
infauna
The
~~~rl~~~r~~~l by the Plastic pipe.
do
laqe
is
~~rri~~r~
and
The
small cl& is used in feeding.
Photo by
four times as much
lea?,
Woods
..
Oceanagraphic
~~~~~~u~"~~n.
c r a b s
All
22
a n i m a l s
g r i n d
u p
Table 2.
Fishes
inhabiting
Great
Sippewissett Salt Marsh, Massachusetts
(from Werme 1981).
They are listed in
approximate order of abundance within each
group.
detritus and inoculate it with microbes in
of feeding (Welsh 1975).
the course
(1980) found that the
Cammen et a 1.
epifauna assimilated (i.e., used for their
own life processes) only about one-tenth
Thus, nine-tenths
of what they consumed.
passed through their bodies as feces,
ground and inoculated with microbes In the
The macrofauna are important
process.
and
detritus,
consumers of
algae,
meiofauna on the surface of the mud; they,
in turn, are fed upon by fish and birds,
thereby linking them to the productivity
of the salt marsh.
4.2.2.
Common name/
Scientific name
Fishes that spend most of their lives
within the marsh:
Atlantic silverside
Menidia menidia
Fishes
mummichog
Fundulus heteroclitus
Salt marsh fishes are among the most
highly valued animals of the marsh because
and recreational
their
commercial
of
The fishes of the salt marsh
importance.
the relatively
into
can be divided
permanent residents and those that spend
there
stages
their
early
life
only
(1981) provided an
Werme
(Table 2).
excellent description of the marsh fishes
of the Great Sippewissett Salt Marsh, and
the bulk of the following comes from that
work.
striped killifish
Fundulus majalis
sheepshead minnow
Cyprinodon variegatus
four-spined stickleback
q
Apeltes
u a d r a c u s
three-spined stickleback
Gasterosteus aculeatus
common eel
Anguilla rostrata
The silverside is a small, schooling
fish that is resident in inshore waters
The species is
throughout its life.
present in Cape Cod marshes from spring
through summer and reaches its maximum
abundance .
l::e
generally
relatively few that survive the winter by
retreating to deeper water return in
spring to spawn and produce the next
generation.
Nevertheless, silversides are
Fishes that use the marsh mostly'as a
nursery area:
winter flounder
Pseudopleuronectes
americanus
tautog
o
Tautoga
n i t i s
sea bass
Centropristes
alewife
Alosa
midwater in the marsh creeks, though as
much as 30% of the population may be found
in the Spartina on the creek banks at high
striata
pseudoharengus
menhaden
Brevoortia tyrannus
bluefish
Pomatomus saltatrix
planktonic animals, but algae and detritus
have also been found in their guts after
they have been on the marsh surface.
Horseshoe crab eggs and small amphipods
from the marsh may be their major food
items in summer; mysid shrimp and copepods
are important foods in autumn.
mullet
c
Mugil
e p h a l u s
sand lance
Ammodytes
americanus
striped bass
Morone saxatilis
The mummichog (Figure 15), which can
live for several years, is the fish most
23
intimately
associated
with
the
grassy
parts of the regularly flooded marsh- It
is probably best known of aTT the marSh
At 10~ t i d e s , mummichogs T1@
minnows.
near the bottoms of creeks, but return
toward the grass with flood tides- At
high tide, they are found alITlOSt entireJy
within
theAlthough
Spartina
mUmmichogS
(FigWe 14).
feed o n
al
1 SOrtS o f plant
(including algae and detrWsL
they Tack the digestive system required to
from
it
value
derive much nutrient
(Prinslow et al. 1974). Animals comP0se.a
large part of the mummichog diet early 1"
algae constitute the major
the year;
portion later in the year when animal
Over 5 0 % of
populations have declined.
the diet of 1- to J-cm long mummichogs
is meiofauna (Werme 1981); mummichog young
the
form an important 1 ink between
meinfauna they consume and the other fish
which consume them.
material
Mummichogs spawn beside grass stems
and macroalgal clumps at spring tides.
The eggs fall into and are hidden in
crevices which prevents their being eaten
(often by their parents). The eggs attach
to plants or other objects by means o f
a d he sive threads.
The fry, as well as the
adults, are resistant to stresses such as
tligtr temperatures or low oxygen levels.
~~Jit~mi~t~og fry are the minute fish often
ww in Pools on the marsh surface at low
tides.
Mummichogs survive winter at the
~~o~t~ln~ of the marsh creeks, often in the
~J~~~~rrn(~~t, brackish parts of the marsh
Q'sk-@m, or they may lie semidormant in the
m~ld(~Y bottoms of marsh pools.
inarsrj than doeS the mummichog.
The sand
in 'neFr guts indicates that they obtain
24
the majority of their food from areas
other than the marsh.
Perhaps the grass
is of greater relative value for the
refuge
killifish as a
from predation
rather than as a food resource.
Both
Fundulus species take less than 10% of
their food from the zooplankton.
into freshwater as elvers or out of
freshwater as adults.
However, they may
also spend their entire lives in salt
m a rSht? S where they are found mainly in the
muddy marsh creeks.
Werme (1981) found
that the eels in her samples had fed
mostly upon benthic invertebrates.
Eels
eat fish readily as can be seen by putting
minnow
traps
into
the
marsh
creeks
overnight:
mummichogs enter the traps and
serve as bait for the eels that enter at
night; by morning, the mummichogs have
been eaten and the eels remain in the
traps.
The sheepshead minnow also occurs in
New Enaland salt marshes, thouah less
the
than
related
regularly
Fundulus
Its lonaer aut is characteristic
soecies.
of feeders on vegetable materials and is
typically full of algae and detritus.
Thus, the sheepshead minnow is apparently
more herbivorous than its relatives (Werme
1981).
The more common fishes that use Great
Sippewissett Salt Marsh as a nursery are
listed in
Table 2.
These
are
the
commercially
and
recreationally
significant fishes found
in
the New
Not as abundant
England salt marshes.
as the residents, they rarely get up
into the grassy parts of the marsh but
are generally confined within the creeks.
Alewives pass through the marsh en route
to their freshwater spawning grounds, and
their juveniles live in the marsh during
Menhaden, which are much
late summer.
abundant in the marshes of the
more
southeastern U.S. coast, also live in
They eat
Great Sippewissett in summer.
phytoplankton, whereas the alewives eat
The primary value of the
zooplankton.
marsh for schools of these young fish is
probably as a shallow refuge area. Mullet
feed on detritus and benefit from marsh
its
well
as
from
productivity
as
protective shallows.
marsh
sticklebacks,
Of
the
the
three-spined (Gasterosteus aculeatus) is
oresent in New Enaland marshes only in
diring
its
spring
breeding
early
While
there, it
feeds
activities.
principally on zooplankton during daytime
The three-spined stickleback
high tides.
nest builder.
The male
is a typical
builds a barrel-shaped nest out of grass
other
bits of
vegetation glued
and
his
secretion
from
with
a
together
kidneys.
He attracts females to spawn
within the nest, fertilizes the eggs, and
then fiercely guards the nest area. Just
before hatching occurs, he tears the top
off the nest to aid the fry's escape and
continues to guard them until they can
The four-spined
for themselves.
care
stickleback
(Apeltes quadracus) is a
permanent resident of the salt marsh. It
This
also feeds mostly during daylight.
species feeds on meiofauna in the marsh
shallows to which it has access only at
The nine-spined stickleback
high tides.
(Pungitius pungitius) is a more northern
species than the other two and is common
in salt marshes north of Cape Cod.
The remainder of the fish listed in
Table 2 also primarily use the New England
Young winter
marsh in their young stages.
the
throughout
present
are
flounder
summer; tautog and seabass appear in late
These three species are all
summer.
bottom feeders and seem to prefer the
Tautag and
sandier parts of the marsh.
bass eat amphipods and isopods, although
the bass also eat small fish and shrimp.
The young winter flounder concentrate
Werme
their feeding on annelid worms.
(1981) has shown that young flounder,
tautog, and seabass all have larger mouths
As a
than the same size killifish.
result, they eat food items larger than
can be handled by the killifish and SO do
During
not compete with them for food.
are
non-residents
these
when
summer
Common eels (Anguilla rostrata) live
in the marshes only after they arrive as
Adult eels spawn in
elvers from the sea.
the center of the Sargasso Sea at some
For about a year after
unknown depth.
the
with
drift
hatching,
the young
leaf-shaped
transparent,
currents as
larvae (leptocephali) until they near the
They then become cylindrical in
shore.
shape (elvers) and enter the COaStal
areas.
Eels may merely pass through the
salt marshes as they move through the area
25
Striped biSb$ and bluefish enter salt
moderate- to large-sized
~~Y~~ cweks ae,
The size of fish that can enter
adults.
the marsh depends on the depth of the
These
creeks and the height of the tides.
adults prey directly upon the smaller
The use of the
fishes in late summer.
marsh by these larger fish species is
perhaps more to be likened to the use by
fish-eating birds than by other fishes.
these
for
plentiful
are
Small
prey
carnivores.
CHAPTER 5. SALT MARSH PROCESSES
5 . 1 PRODUCTlVlTY
5.1.1.
resources
and may also
reduce oxygen
availability to the roots which could, in
turn, inhibit nutrient uptake.
Higher Plants
For years the salt marsh has been
considered one of the most productive
natural systems on earth (Teal 1962; Odum
1971).
Production
values
range from
nearly
4,000 g/m2
year
in
the
per
streamside marshes of Georgia (Odum and
Fanning 1973) to only a little more than
one-tenth of that in the short Spartina
alterniflora
marshes
of Rhode Island
INixon and Oviatt 1973) and Massachusetts
(Ruber et al.
1981).
There
is
a
latitudinal
variation in
salt
marsh
productivity,
with the highest values
occurring in the southern States.
Levels
decrease by one-half to two-thirds in the
north,
presumably due to the shorter
growing season and lower solar input at
the higher latitudes (Turner 1976). In
the salt marshes of the eastern United
States there appears to be about a
threefold variation in production over the
latitudes at which Spartina alterniflora
marshes grow, and also about a threefold
variation in production within any one
marsh.
Part of the variation in Spartina
productivity within a marsh is related to
sediment salinity (Nestler 1977; Smart and
Spartina can, in.fact, grow
Barko 1980).
almost
well
in
freshwater
sites if
normally occurring freshwater plants are
If such plants are present, they
removed.
outcompete (grow better than) Spartina and
Spartina does well in more
crowd it out.
saline locations because it has mechanisms
for coping with salt stress (as discussed
in Chapter 3).
However, an increase in
respiration is necessary for the plants to
osmotic
gradient
maintain
the
higher
required at high salinities (Figure 7);
lowers
production.
Increased
this
respiration uses up some of the plant's
27
Soil densitv is another factor which
can affect Spartina productivity. DeLaune
et al. (1979) found that in Louisiana.
Spartina‘ is more productive in soils of
high density.
This high density is the
result of great amounts of mineral matter
and accompanying high nutrient levels. In
the higher density soils in
addition,
Louisiana are also those without much
they are
more
peat.
As
a
result,
permeable to water movements and attendant
flushing actions.
A
substantial
portion of
the
production of Spartina alterniflora has
been measured in the belowground parts of
the plants: the roots and rhizomes (Table
data
indicate
there is
These
3).
typically more production underground than
aboveground in the most productive parts
of the marsh,
more
and considerably
underground
production in
the
less
productive
salt
marsh
areas.
All
production (i.e., photosynthesis) takes
However, in the less
place in the leaves.
productive parts of the marsh, a great
deal of the organic matter produced is
translocated
underground
and
used to
construct roots and rhizomes.
The grasses
seem to behave as if they first produce
enough
underground
parts to
acquire
and then put any
nutrients
necessary
excess into the photosynthetic machinery,
i.e., leaves.
In the richer parts of the
marsh (the creek banks or tall grass
marsh), nearly equal amounts of biomass
are produced above and below the sediment
This distribution of biomass has
surface.
considerable
significance
for
what
eventually happens to salt marsh primary
production, a point to which we will
return.
Table 3. Comparison of above- and belowground p r o d u c t i v i t y i n S p a r t i n a a1 t e r n i f l o r a in
g d r y weight/m2/yr.
Area
Type of
grass
Aboveground
Belowground
Ratio
be1 ow/above
Mississippi
Georgia
N o r t h Carolina
N o r t h Carolina
New J e r s e y
Massachusetts
Nova Scotia
Reference
de l a Cruz 1974
de l a Cruz 1977
Gal 1agher e t a1 . 1980
Gal l a g h e r and Plumley 1979
S t r o u d 1976
S t r o u d 1976a
S t r o u d 1976a
S t r o u d 1976
Smith e t a l . 1979
V a l i e l a e t a l . 1976
Val i e l a e t a l . 1976
L i v i n g s t o n and P a t r i q u i n
1981
tall
short
tall
short
tall
short
tall
short
"old
stands''
a R e c a l c u l a t e d u s i n g method o f V a l i e l a e t a l . (1976).
Odum (1969) suggested t h a t t h i s h i g h
p r o d u c t i v i t y was due t o a t i d a l subsidy.
I n o t h e r words, t h e t i d e s c o n t r i b u t e d
s o m e t h i n g t o t h e marsh t h a t enhanced p l a n t
production.
Steever e t a l . (1976) found
they c o u l d a s s o c i a t e about 90% o f t h e
v a r i a t i o n i n S p a r t i n a p r o d u c t i v i t y i n Long
I s l a n d Sound w i t h t h e t i d a l range, which
v a r i e d f r o m 0.7 m t o n e a r l y 2.3 m. I n one
s i t e , a p o r t i o n of the marsh was behind a
t i d e g a t e t h a t r e s t r i c t e d t i d a l movement
and r e d u c e d t h e p l a n t production by 26%
relative
t o t h e r e s t of the marsh.
F u r t h e r m o r e , t h e y showed t h a t a s t r o n g
r e 1 a t i o n e x i s t s between p r o d u c t i o n and
t i d a l r a n g e a l l along t h e A t l a n t i c coast.
CI e a r l y , w a t e r movement i s associated w i t h
sa7 t marsh production; t h e mechanisms
in v o l v e d i n c l u d e n u t r i e n t supply, waste
r e m o v a l , and s a l i n i t y c o n t r o l , o r a l l of
t h e s e combined.
A l l o f the
w i t h t h e s a l t s i n t h e water.
m i n o r n u t r i e n t s needed b y p l a n t s , as we1 1
as t h e m a j o r n u t r i e n t potassium, a r e
present
in
seawater.
The
major
nutrients--ni trogen,
phosphorus,
and
potassium CN, P, and K)--are a l s o i n good
s u p p l y i n t h e marsh mud a l o n g t h e c r e e k
banks. (Potassium i s p l e n t i f u l t h r o u g h o u t
t h e marsh s i n c e i t i s so abundant i n
Carbon d i o x i d e n o t o n l y
seawater. )
e n t e r s t h e p l a n t f r o m t h e atmosphere
through i t s leaves, b u t a l s o through i t s
r o o t s f r o m C02 r e s e r v e s i n c r e e k bank
soils.
With these p l e n t i f u l n u t r i e n t s ,
S p a r t i n a g r o w i n g on New England c r e e k
banks has a p r o d u c t i v i t y comparable t o
t h a t o f p l a n t s g r o w i n g n a t u r a l l y anywhere.
The maximum t o t a l annual marsh p r o d u c t i o n
i n New England i s l e s s t h a n t h a t o f more
s o u t h e r l y marshes o n l y because t h e g r o w i n g
season i s s h o r t e r i n t h e n o r t h .
S a l t marsh p r o d u c t i v i t y i s high,
especiall y
that
of
the
Spartina
3 1 t e r n i f l o r a growing along the creek
b a n k s , because of t h e almost i d e a l factors
f o r g r o w t h found there. There i s a l a c k
o f c o m p e t i t i o n along creek banks, which
g i v e s t h e p l a n t s space and an abundance of
.unl i g h t .
The water supply i s p l e n t i f u l
and S p a r t i n a has mechanisms f o r d e a l i n g
Experiments a t G r e a t S i p p e w i s s e t t
S a l t Marsh have shown t h a t t h e a d d i t i o n o f
f e r t i l i z e r increases t h e p r o d u c t i v i t y o f
S p a r t i n a a1 t e r n i f l o r a i n a1 1 p a r t s o f t h e
marsh e x c e ~ t h e a1 r e a d y h i a h l y p r o d u c t i v e
Once
c r e e k banks (Val i e l a a d ~ e a 1974).
l
t h e a d d i t i o n o f n i t r o g e n t o t h e marsh
produces i t s maximum e f f e c t , p r o d u c t i o n
can be f u r t h e r
i n c r e a s e d by a d d i n g
phosphorus ( F i g u r e 17), though phosphorus
pg-at/l.
F o r phosphate, t h e range i s 5 t o
20 p g - a t / l ( V a l i e l a and Teal 1974). The
c o n c e n t r a t i o n s o f these i o n s i n seawater
a r e u s u a l l y l e s s than 1 p g - a t / l .
N i t r o g e n uptake r a t e s b y S p a r t i n a i n
an e x p e r i m e n t a l ,
o x i d i z e d medium a r e
f a s t e r t h a n uptake r a t e s i n t h e u s u a l l y
reduced sediments i n t h e f i e l d ( M o r r i s
,L '0
A,
.
L- L I.--LA_
1980).
I n c u l t i v a t e d r i c e , which a l s o
T
76
78
80
82
grows i n anoxic s o i l s , n u t r i e n t uptake
YEAR
r a t e s depend on t h e oxygen c o n c e n t r a t i o n
o f t h e s o i l (Ponnamperuma 1972). S p a r t i n a
Figure 17.
Peak biomass o f S p a r t i n a
shows v e r y reduced uptake o f d i s s o l v e d
a1 t e r n i f l o r a i n e x p e r i m e n t a l p l o t s t o
i n o r g a n i c n i t r o g e n when t h e oxygen c o n t e n t
which n i t r o g e n a l o n e (+N) o r n i t r o g e n and
o f t h e growing medium i s l o w ( M o r r i s and
phosphorus (+N+P) were added a t r a t e s o f
Dacey 1984).
These o b s e r v a t i o n s suggest
2.5 g N/m2/week and 1 . 5 g P/m2/week.
t h a t redox c o n d i t i o n s a t t h e r o o t s a r e
C o n t r o l s were n o t f e r t i l i z e d .
(Teal and
i n v o l v e d i n l i m i t i n g n u t r i e n t uptake
Val i e l a , unpubl . d a t a , G r e a t S i p p e w i s s e t t
( L i n t h u r s t 1979; Howes e t a l . 1981).
In
S a l t Marsh, MA).
experiments i n Georgia, W i e g e r t e t a l .
(1983) d r a i n e d marsh s o i 1s w i t h p l a s t i c
t i l e l i n e s t h a t c a r r i e d water from t h e
added w i t h o u t n i t r o g e n has no e f f e c t .
s o i l s t o t h e creeks; S p a r t i n a p r o d u c t i o n
F e r t i 1i z a t i o n i n c r e a s e s marsh p r o d u c t i o n
was
i n c r e a s e d presumably
because o f
as a whole two- t o t h r e e f o l d and c o n v e r t s
i n c r e a s e d sediment o x i d a t i o n .
t h e l e a s t p r o d u c t i v e p a r t s o f t h e marsh
almost t o c r e e k bank p r o d u c t i o n 1eve1 s.
Stands o f t a l l e r p l a n t s grow i n
A t t h a t p o i n t , f u r t h e r growth o f Spartina
r e l a t i v e l y more o x i d i z e d sediments w h i l e
may be l i g h t - l i m i t e d r a t h e r t h a n n u t r i e n t s h o r t p l a n t s a r e found i n more reduced
limited.
S i m i l a r r e s u l t s have been seen
s i t u a t i o n s ( F i g u r e 18).
The h i g h e r redox
i n many o t h e r s a l t marshes ( S u l l i v a n and
Daiber 1974; Broome e t a l . 1975; G a l l a g h e r
1975; Chalmers 1979).
Measurements o f n i t r o g e n r e d u c t a s e
(an enzyme i n v o l v e d i n n i t r o g e n uptake),
comparison o f n u t r i e n t c o n t e n t o f S p a r t i n a
from v a r i o u s p a r t s o f marshes from Nova
S c o t i a t o L o u i s i a n a ( S t e w a r t e t a l . 1973;
S t e w a r t and Rhodes 1978;
Mann 1978;
Mendel ssohn
1979),
and
experimental
r e s u l t s f r o m n u t r i e n t enrichment s t u d i e s
a l l l e a d t o t h e c o n c l u s i o n t h a t s a l t marsh
p l a n t s a r e u s u a l l y n i trogen-1 i m i t e d i n
most p a r t s o f n a t u r a l marshes.
Sedimentredox.
I n view o f t h e
s t u d i e s s u g g e s t i n g n u t r i e n t 1i m i t a t i o n , i t
seems p a r a d o x i c a l t o f i n d t h a t t h e amounts
o f d i s s o l v e d ammoni um and phosphate i n
interstitial
waters
of
salt
marsh
sediments a r e v e r y h i g h . These l e v e l s a r e
more t h a n s u f f i c i e n t t o p r o v i d e a l l t h a t
S p a r t i n a can t a k e up i f t h e r o o t s a r e i n
an o x i d i z e d environment (Val i e l a and Teal
1978; M o r r i s 1980).
N i t r a t e nitrogen
c o n c e n t r a t i o n s range f r o m 0 t o 50 p g - a t / l
and ammonia n i t r o g e n from 10 t o 500
/
Short
/
Figure 18.
Redox (Eh) p r o f i l e s i n a)
sediments w i t h t a l l and s h o r t S p a r t i n a
a l t e r n i f l o r a , and b) an a r e a o f marsh i n
w h i c h grass was smothered and a nearby
area i n which t h e grass was becoming
r e e s t a b l ished (Howes e t a1 1981).
.
values are p a r t l y due t o d i f f e r e n c e s i n
p h y s i c a l p r o p e r t i e s o f t h e sediments t h a t
lead
to
increased
rates
of
water
percolation.
I n addition, the t a l l e r ,
more vigorous p l a n t s are more e f f i c i e n t i n
o x i d i z i n g t h e sediments than a r e t h e s h o r t
plants.
This r e s u l t s
i n a complex
feedback system i n which p l a n t s , redox
l e v e l , and n i t r o g e n a v a i l a b i 1it y i n t e r a c t
t o c o n t r o l marsh p r o d u c t i o n (Howes e t a l .
I f p r o d u c t i v i t y o f a stand
1981, 1986).
o f Seartina i s stimulated by n u t r i e n t
addi t ~ o n s ,t h e r e i s increased o x i d a t i o n of
t h e sediments by t h e p l a n t s .
The more
biomass o f t h e p l a n t s increases, t h e more
o x i da t i or1
occurs,
which
should
( t h e o r e t i c a l l y ) l e a d t o more uptake o f
A
n i t r o g e n and increased p r o d u c t i v i t y .
s u b s t a n t i a l p a r t o f the observed increase
i n oxygenation o f sediments i s caused by
water removal from t h e sediments by
t r a n s p i r a t i o n o f Spartina.
As t h e water
i s removed, t h e sed~mentdoes n o t decrease
i n volume b u t t h e spaces p r e v i o u s l y
occupied by w a t ~ r become f i l l e d w i t h a i r
(Dacey a t ~ d tiowes 1984).
The sediment
s t i l l r e t a i n s t h e m a j o r i t y o f i t s pore
water much li k e a sponge which has been
a1 lowed t o d r a i n . Sediment o x i d a t i o n may
a1 so
aided by t r a n s p o r t o f gases i n gas
spacer
inside
the plant
(Teal
and
Kanwisher 1966), o r by release o f organic
o x i d a n t z such as g l y c o l a t e from t h e r o o t s
(Armstrong 19GI), o r by both.
, the
i s the
ut
microbial
deconiposition.
rc:~;ult
Uecausca o f t h e l i m i t e d a b i l i t y o f oxygen
t o move thr'ouyh sediments by d i f f u s i o n ,
oxygeri i s tu-sually absent below t h e t o p few
m i l limetors
of
marsh
muds.
The
cfeco~nposer.~ below
this
depth depend
i i r i n c i y t r l l y on the r e d u c t i o n o f s u l f a t e
for. Lhtli r rrlergy.
They " r e s p i r e 1 ' u s i n g
su I f dte r d t h e r t,tiati oxygen arid produce
s u l f i d e as n product. The redox o f s a l t
marsti s o i Is i s c l o 3 e l y c o r r e l a t e d w i t h
s u 1 f id@ ror\c.entration.
The
balance
between the very h i g h r e d u c i n g power
r e s u l t i n g trom m i c r o b i a l a c t i v i t y and t h e
0 x i d d t . i ~ ~action
of
higher
plants
rfett~rmine!, t h e redox s t a t e of t h e s o i l ,
w h i c h i n t u r n a f f e c t s n u t r i e n t uptake.
l l s c ~ d l y t h e reducing a c t i v i t i e s o f t h e
micro-organi sms p r e v a i 1 and, a l t h o u g h t h e
p l a n t s may make the s a i l s l e s s reduced, an
o x i d i z e d s t a t e i s r a r e and t h e m a j o r i t y o f
I h~ o p p o s i t e
tendency
(
sedinre~lt becomes more reducing)
e.
marsh sediments
are
h i g h l y reduced.
S p a r t i na r o o t s can r e s p i r e a n o x i c a l l y , b u t
i n c o n d i t i o n s o f extreme w a t e r l o g g i n g and
r e d u c t i o n , t h e p l a n t s c a n n o t compensate,
so p r o d u c t i o n i s s e v e r e l y r e d u c e d and
dieback may o c c u r (Mendelssohn e t a l .
1981).
S u l f i d e , which i s r e s p o n s i b l e f o r t h e
low redox values o f s a l t marsh s o i l s , i s
t o x i c t o wetland p l a n t s .
T h i s has been
demonstrated f o r r i c e b y J o s h i e t a l .
(1975) and f o r S p a r t i n a by Mendelssohn
e t a l . (1982).
I n v e r y reduced marsh
sediments, such as t h o s e where s h o r t
plants
of
Spartina
grow,
sulfides
undoubtedly c o n t r i b u t e t o t h e i n h i b i t i o n
of f u r t h e r g r o w t h by c o u n t e r a c t i n g t h e
o x i d i z i n g a c t i v i t i e s o f r o o t s and perhaps
by p o i s o n i n g them.
To e x p l a i n t h e c o n c l u s i v e r e s u l t s of
fertilization
experiments
in
Great
Sippewissett
Salt
Marsh,
one
must
understand
the
relationships
between
sediment redox and S p a r t i n a p h y s i o l o g y .
The S i p p e w i s s e t t marsh e x p e r i m e n t s s u g g e s t
t h a t under r e d u c i ng c o n d i ti ons, much l e s s
n i t r o g e n can be p i c k e d up by p l a n t s t h a n
i s possible i n oxidized s o i l s .
Thus, i n
reduced
sediments,
only
a
greatly
increased
concentration
of
dissolved
nitrogen
(such
as
is
provided
by
f e r t i l i z i n g ) allows uptake t o occur a t
r a t e s s i m i l a r t o t h o s e found i n o x i d i z e d
soils.
T h i s h y p o t h e s i s i s s u p p o r t e d by
t h e f i n d i n g s o f L i n t h u r s t (1980),
who
showed i n greenhouse experiments t h a t
while the a d d i t i o n o f n i t r o g e n doubled t h e
biomass o f S p a r t i n a , n i t r o g e n a d d i t i o n
p l u s a e r a t i o n o f t h e r o o t i n g medium
increased biomass b y a f a c t o r o f 4.5. He
suggested t h a t S p a r t i n a p r o d u c t i o n i n t h e
marsh i s r e g u l a t e d by a c o m b i n a t i o n o f
n i t r o g e n , sa1 i n i t y , pH, and a e r a t i o n .
5.1.2.
Other A u t o t r o p h s
T o t a l p r o d u c t i o n o f t h e s a l t marsh
system i s t h e sum o f t h e p r o d u c t i o n o f t h e
h i g h e r p l a n t s and t h a t o f a l l t h e o t h e r
a u t o t r o p h s , i n c l u d i n g t h e a l g a e 1i v i n g on
surfaces, p h y t o p l a n k t o n i n t h e w a t e r ,
photosynthetic
sulfur
bacteria,
and
chemoautotrophic
iron
(and
sulfur)
bacteria.
The c o n t r i b u t i o n s o f none o f
these a u t o t r o p h s have been a c c u r a t e l y
measured and a r e assumed t o be s m a l l
r e l a t i v e t o t h e o t h e r primary producers.
The chemosynthetic organisms do not
c o n t r i b u t e t o o v e r a l l marsh production i f
they a r e o x i d i z i n g reduced substances
produced i n t h e marsh ( s e e Section
5.5.4.).
Measurements of benthic microalgal
production along t h e A t l a n t i c c o a s t (Table
4 ) i n d i c a t e t h a t a l g a l production i n t h e
grassy p a r t s of t h e Massachusetts marsh i s
l i m i t e d by low l i g h t during the darker
p a r t s of t h e y e a r (Van Raalte e t a l .
1976).
There i s l i t t l e i n d i c a t i o n of
i n h i b i t i o n by high l i g h t i n t e n s i t y i n any
s t u d i e s ( s e e Pomeroy and Wiegert 1981).
Competition f o r a v a i l a b l e n u t r i e n t s by
g r a s s e s during t h e i r growing season a l s o
l i m i t s a l g a l production.
Microscopic a l g a e make a s i g n i f i c a n t
contribution
to
total
sal t
marsh
production
because they contain low
amounts of r e f a c t o r y s t r u c t u r a l compounds
and, t h u s , a r e b e t t e r food than higher
plants.
The l i g n i n s and c e l l u l o s e s of
higher p l a n t s a r e a l l r e l a t i v e l y r e s i s t a n t
t o d i g e s t i o n by animals. We usually speak
of them a s " r e s i s t a n t t o degradation,"
implying t h a t they a r e attacked only by
microbes and, in t h e case of 1 ignins , very
slowly.
Algae, on t h e o t h e r hand, a r e
eaten r e a d i l y by benthic animals, a s has
been demonstrated by excluding mud s n a i l s
from rnarsh a r e a s and observing t h e
i n c r e a s e i n a l g a l biomass (Pace e t a i .
1979). Pace e t a l . (1979) found t h a t t h e
s n a i l s only reduced a l g a l populations by
grazing and caused no r e l a t e d increases i n
a l g a l p r o d u c t i v i t y in t h e i r Georgia marsh.
O n t h e o t h e r hand, Connor e t a l . (1982)
found t h a t a t moderate population l e v e l s ,
the n u t r i e n t s (ammonia) excreted by the
s n a i l s stimillated algal production.
An
increase i n production when g r a z e r s a r e
excluded has a l s o been shown i n e a r l y
spring when blooms of Beggiatoa were
produced in Great Sippewissett Sal t Marsh
by fencing Furidulus out of marsh creeks
(J.M. Teal, unpubl. d a t a ) .
S a l t marsh phytoplankton prodilctivi t y
may be high, e s p e c i a l l y a t high t i d e when
the water i s c l e a r from being f i l t e r e d by
the marsh and
nutrient
levels are
maintained by marsh-to-water exchanges.
In Georgia marshes, phytoplankton a r e
estimated t o c o n t r i b u t e about half a s much
t o t h e system a s do benthic a l g a e (Pomeroy
and Wiegert 1981) ; in Massachusetts,
phytoplankton productivity may be about
equal to t h a t of benthic algae (Van Raalte
e t a l . 1976). Pomeroy and Wiegert (1981)
showed t h a t phytoplankton photosynthesis
is
inhibited
by
low
in
Georgia
temperatures i n winter; Gl i b e r t e t a l .
(1984)
have
found
high
l e v e l s of
phytoplankton
photosynthesis
in
Massachusetts
coastal
inshore
waters
If t h i s d i f f e r e n c e i s
during winter.
r e a l , then phytoplankton may be even more
important t o New England marsh creeks than
we previously thought.
Algal production in surface pools of
a s a l t marsh was measured by Ruber e t a l .
(1981). They estimated an ash-free dry
weight value of 514 g/m2/yr, which i s a
t i t t l e more than the production of dwarf
Spartina in New England and s l i g h t l y l e s s
than
half
that
of
tall
Spartina,
Planktonic diatoms and d i n o f l a g e l l a t e s
Table 4. Production of benthic algae in s a l t marshes along the A t l a n t i c c o a s t .
State
Georgia
Georgia
Del aware
Massachusetts
Benthic a l g a l
production
( g C/m2/yr)
180
190
80
42
Percent of
aboveground
grass production
(%>
25
25
33
25
Reference
Pomeroy 1959
Whi tney and Darley 1981
Gal lagher and Daiber 1974
Van Raalte e t a l . 1976
were
responsible f o r
mast o f t h i s
production; f l o a t i n g mats o f Cladophora
were a l s o important.
5.2
5.2.1.
DECOMPOSITION
Aboveground
A p a r t o f the marsh grass produced
each y e a r i s eaten d i r e c t l y by herbivores
feeding on t h e grasses and by animals
e a t i n g t h e a l g a e from the marsh surface o r
f i l t e r i n g i t o u t o f the water.
Another
measurable
amount
of
production
is
released d i r e c t l y i n t o t h e water when
l i v i n g leaves are immersed by h i g h t i d e s .
This
portion
amounts
to
about
60 kg C/halyr i n Georgia (Gal lagher e t a1 .
1976), which i s a l i t t l e l e s s than 1% o f
the t o t a l p r o d u c t i o n f a r t h a t region.
This m a t e r i a l i s very r e a d i l y absorbed by
microbes and can promptly enter t h e food
web. The l o s s i s probably s i m i l a r i n New
England ( V a l i e l a e t a l . , unpubl. data).
Almost
three-quarters
of
the
aboveground p l a n t biomass produced i s n o t
consumed d i r e c t l y .
I t d i e s i n place on
the marsh s u r f a c e and decomposes t o
v a r i a b l e e x t e n t s before being eaten by
animals. It may decompose i n p l a c e o r i n
a l o c a t i o n t o which i t has been c a r r i e d by
t h e t i d e s . The g r e a t e s t exception t o t h i s
i s i n areas where snow geese congregate
during the w i n t e r ; they may e a t over h a l f
o f the annual production, which a t t h a t
time may be s t o r e d mainly belowground as
rhizomes (Smith and Odum 1981).
Since
geese have v e r y i n e f f i c i e n t d i g e s t i v e
systems t h a t remove o n l y s o l u b l e compounds
from t h e i r food, most o f what they e a t i s
s t i l l decomposed on the surface o f t h e
marsh by b a c t e r i a and f u n g i .
The
c e l l u l o s e i n t h e grass passes through t h e
d i g e s t i v e systems o f the geese almost
unchanged except t h a t i t i s broken i n t o
small b i t s and i s probably more r e a d i l y
attacked by t h e micro-organisms as a
result.
Late i n t h e growing season, p l a n t s
enter
senescence
and
the
grass
decompos it i o n process begi ns. The 1eaves
become l e a k y t o b o t h organic compounds and
t o n u t r i e n t s and l o s e l a r g e amounts o f
s o l u b l e compounds t o t h e water. The dead
leaves f a 1 l o n t o the mud surface and a r e
invaded b y f u n g i and b a c t e r i a .
I n Great
Sippewi s s e t t S a l t Marsh, t h e aboveground
decay process o c c u r s i n t h r e e stages once
t h e p l a n t s have d i e d and become a p a r t o f
the l i t t e r .
I n t h e l e a c h i n g phase, t h e
l i t t e r l o s e s about o n e - t h i r d o f i t s weight
w i t h i n 2 weeks as a r e s u l t o f f u r t h e r l o s s
o f s o l u b l e components.
I n t h e second o r
decomposer phase, t h e s t r u c t u r a l p a r t s of
t h e l e a f a r e a t t a c k e d b y micro-organisms.
The l o s s o f m a t e r i a l f r o m t h e l i t t e r i s
slower t h a n i n t h e l e a c h i n g phase b u t
occurs more r a p i d l y t h e more f r e q u e n t l y
A t t h e end o f a
t h e l i t t e r i s submerged.
year o n l y about 10% o f t h e o r i g i n a l 7 i t t e r
remains
(Figure
19).
The r e f r a c t o r y
phase, which b e g i n s about 1 y e a r a f t e r t h e
p l a n t s d i e , o c c u r s , as t h e name i m p l i e s ,
100
R
Welghl of litter remaining
1 Percent nitroaen
*
e
0
F, Nitrogen enriched
C. Control
4
,
N D
J F M A M J
J
A S O N D J
,
,
,
F M A
Figure 19.
Results
of
aboveground
decomposition
experiments
at
Great
Sippewi s s e t t S a l t Marsh.
These 1 it t e r
bags were i n c u b a t e d i n c r e e k bank marsh.
The l e a c h i n g phase i s shown by t h e r a p i d
w e i g h t l o s s between t h e f i r s t two p o i n t s ;
t h e decomposer phase i s t h e p e r i o d of
steady d e c l i n e i n w e i g h t up t o t h e second
w i n t e r ; t h e r e f r a c t o r y phase f o l l o w s w i t h
very l i t t l e weight loss.
(Teal
and
Val i e l a , unpubl . d a t a , G r e a t S i p p e w i s s e t t
S a l t Marsh, MA).
very slowly.
A f t e r 2 y e a r s , about 5% o f
t h e i n i t i a l l i t t e r s t i l l remains.
These
remnants a r e i n d i s t i n g u i s h a b l e from t h e
o r g a n i c m a t t e r o f t h e sediments and a r e
presumably what accumulates as marsh peat.
D u r i n g b o t h t h e l e a c h i n g and decomp o s i t i o n phases, t h e more l u x u r i a n t t h e
marsh t h a t produces t h e l i t t e r , t h e more
n i t r o g e n t h e l i t t e r w i l l c o n t a i n and t h e
more r a p i d w i 11 be i t s decomposi t i o n ( F i g u r e 19).
I n t h e Great Sippewissett S a l t
Marsh, t h e r a t e o f decomposition a l s o
i n c r e a s e d i f t h e e x t r a n i t r o g e n was added
t o t h e marsh s o i l r a t h e r t h a n b e i n g w i t h i n
t h e l e a f . The same e f f e c t was produced i f
n i t r o g e n was e n r i c h e d i n t h e s o i l water
e i t h e r experimentally o r by p o l l u t i o n o f
t h e marsh ( V a l i e l a e t a l . 1984) ( F i g u r e
20).
The f a c t t h a t n i t r o g e n enhances
decomposition whether i t i s i n t h e p l a n t
t i s s u e o r t h e environment o f t h e decomposer organisms i m p l i e s t h a t t h e r e i s a
n i t r o g e n l i m i t a t i o n t o decomposition as
w e l l as t o p r i m a r y p r o d u c t i o n i n t h e
marsh.
Incubated in
, F
FPlot
0
C Plot
J
DAYS
Figure 2 0 . Decay o f S p a r t i n a l i t t e r under
d i f f e r e n t c o n d i t i o n s o f n i t r o g e n presence.
L i t t e r f r o m c o n t r o l p l o t s (C P l o t ) was
i n c u b a t e d i n t h e p l o t s i n which t h e y grew
and i n f e r t i l i z e d p l o t s (F P l o t ) where
t h e r e was h i g h e r n i t r o g e n i n t h e l i t t e r ' s
environment. L i t t e r f r o m f e r t i 1i z e d p l o t s
simi l a r l y
treated.
Only c o n t r o l
was
l i t t e r i n u n f e r t i l i z e d p l o t s decayed more
slowly than the others.
(Teal
and
Val i e l a , unpubl . d a t a , G r e a t S i p p e w i s s e t t
S a l t Marsh, MA).
Since t h e i n i t i a l l o s s e s o f n i t r o g e n
it i s not
from l i t t e r a r e s o l u b l e ,
s u r p r i s i n g t h a t over time, t h e r e m a i n i n g
n i t r o g e n i n t h e d e t r i t u s i s l e s s and l e s s
soluble.
A f t e r 1 y e a r , amino a c i d s s t i 11
c o n s t i t u t e about 20% o f t h e remaini n g
nitrogen, b u t they are almost e n t i r e l y
bound t o i n s o l u b l e compounds i n t h e 1 i t t e r
and are presumably r e s i s t a n t t o decay.
I t has been known f o r some t i m e t h a t
as
detritus
ages,
its
relative
c o n c e n t r a t i a n o f n i t r o g e n i n c r e a s e s (Odum
and de
l a Cruz 1967;
F i g u r e 19).
S c i e n t i s t s i n i t i a l l y be1 i e v e d t h a t t h i s
increase r e p r e s e n t e d t h e n i t r o g e n i n
microbes on t h e d e t r i t u s and t h a t aged
d e t r i t u s was improved as a f o o d source f o r
marsh animals.
L a t e r , r e s e a r c h e r s found
t h a t b a c t e r i a contribute o n l y a small
p e r c e n t o f t h e t o t a l n i t r o g e n i n decaying
S p a r t i n a (Rublee a t a l . 1978). Fungi may
c o n t a i n about o n e - f i f t h o f t h e n o n - p r o t e i n
n i t r o g e n i n d e t r i t u s (Odum e t a l . 1979a).
I n any event, t h e r e i s n o t s u f f i c i e n t
m i c r o b i a l biomass t o account f o r a l l o f
t h e n i t r o g e n i n t h e d e t r i t u s (Lee e t a l .
1980). A p o r t i o n o f t h i s unaccounted-for
n i t r o g e n i s c e r t a i n l y i n t h e form o f
extracell ular
compounds
produced
by
microbes; many o f these compounds a r e
p r o b a b l y r e s i s t a n t t o decomposition. Some
n i t r o g e n i s a l s o bound a s p r o t e i n s t o
o x i d i z e d p h e n o l i c compounds t h a t come f r o m
t h e degradation o f l i g n i n ( a s t r u c t u r a l
component o f p l a n t s ) o r t h a t a r e p r e s e n t
i n t h e p l a n t as s o - c a l l e d "secondary
p r o d u c t s " (compounds which may p r o t e c t t h e
p l a n t from b e i n g eaten).
Aside from t h e
m i c r o b i a l biomass i t s e l f , most o f t h e
n i t r o g e n o u s compounds i n d e t r i t u s a r e n o t
readily
available
as
food
for
the
detritivores.
Therefore,
relative
increases o f n i t r o g e n i n d e t r i t u s do n o t
n e c e s s a r i l y enhance i t s f o o d v a l u e f o r
animals.
Animals a r e a b l e t o h a r v e s t microbes
f r o m d e t r i t u s ( J e f f r i e s 1972; We1 sh 1975;
Wetzel
1975,
1976).
Microbes
will
r e c o l o n i z e t h e p a r t i c l e s and grow a t t h e
expense o f compounds l i k e c e l l u l o s e t h a t
a r e n o t r e a d i l y d i g e s t e d by animals.
Animals can t h e n r e p r o c e s s d e t r i t u s and
h a r v e s t t h e microbes a g a i n .
Algae a l s o
grow on processed d e t r i t u s
and may
s i g n i f i c a n t l y enhance i t s f o o d v a l u e .
Apparently,
p u r e d e t r i t u s i s n o t as
nourishing as was once thought.
For
example,
while
mummichogs w i l l
eat
d e t r i t u s , they cannot g a i n weight on a
d e t r i t a l d i e t t h a t i s n o t supplemented
w i t h p r o t e i n (Prinslow e t a l . 1974).
Marsh k i 1 l i f i s h e s , especial l y mummichogs,
feed on d e t r i t u s though much o f i t may g e t
i n t o t h e i r stomachs by accident when they
are r e a l l y seeking animals i n marsh
sediments.
D e t r i t i vores
accelerate
the
decomposition r a t e o f S a r t i n a l i t t e r by
g r i n d i n g the p a r t i c l e s thus c r e a t i n g more
surface by d i g e s t i n g the p a r t i c l e s t o a
small e x t e n t ) and by s t i m u l a t i n g t h e
growth o f decomposers by cropping them.
Such feeding a c t i v i t i e s s t i r up the
particle
accumulations,
increase
the
available nutrients
and oxygen,
and
perhaps remove a n t i - m i c r o b i a l substances
from p a r t i c l e surfaces.
A1 though the
r e l a t i v e importance o f these various
mechanisms i s n o t c l e a r l y understood, t h e
exclusion
of
macrofauna
from
some
decomposition
experiments t r i p 1 ed t h e
amount of l i t t e r t h a t normally remained
a f t e r 1 year ( V a l i e l a e t a l . 1984).
?
5.2.2.
Belowground
As described i n Section 5.1.1., much
o f the production i n s a l t marshes goes
i n t o the belowground p a r t s o f the p l a n t s ,
the roots and rhizomes. The marsh surface
accumulates o n l y a small percent o f the
t o t a l p l a n t production because most o f i t
decomposes i n place o r i s washed away by
the tides.
The belowground p a r t s cannot
be washed o u t and,
therefore,
they
decompose w i t h i n the marsh sediments.
Some o f t h i s underground decomposition
occurs through t h e same aerobic processes
as aboveground decomposition.
But since
most o f t h e sediment i s anoxic, the major
portion o f
underground decomposition
occurs by anoxic means.
Anoxic processes common t o marine
systems use n i t r a t e (deni t r i f i c a t i o n ) and
s u l f a t e ( s u l f a t e reduction) as e l e c t r o n
acceptors i n place o f oxygen.
These
anoxic processes y i e l d l e s s energy t o t h e
microbes t h a t perform them than oxygenconsuming
processes
do
to
aerobic
microbes. There i s s l i g h t l y l e s s energy
produced in t h e case o f deni tri f ic a t ion
but s u b s t a n t i a l l y less i n t h e case o f
sulfate
reduction.
A v e r t i c a l cross
s e c t i o n o f marsh sediments m i g h t r e v e a l
t h e oxygen-using organisms a t t h e surface,
d e n i t r i f i e r s below them, and f i n a l l y t h e
s u l f a t e r e d u c e r s i n deeper l a y e r s .
As
l o n g as oxygen i s p r e s e n t , organisms t h a t
can use oxygen outcompete t h e o t h e r s
s i m p l y because t h e y can o b t a i n energy from
o r g a n i c m a t t e r more e f f i c i e n t l y and t h u s
grow f a s t e r .
A t t h e d e p t h where a l l o f
t h e oxygen has been used, t h e d e n i t r i f i e r s
a r e most e f f i c i e n t , and a t t h e depth where
t h e n i t r a t e i s a l s o exhausted, t h e s u l f a t e
reducers come i n t o t h e i r own.
Carbon d i o x i d e i s a n o t h e r p o t e n t i a l
e l e c t r o n acceptor.
I t s use by microbes
produces reduced carbon o r methane. But,
because o f t h e abundance o f s u l f a t e i n
seawater and t h e s m a l l p o t e n t i a l energy
a v a i 1a b l e from methane p r o d u c t i o n compared
w i t h s u l f a t e reduction, t h i s path o f
decomposition i s o f minimal importance i n
s a l t marshes.
Decomposers t h a t use n i t r a t e and
s u l f a t e as e l e c t r o n a c c e p t o r s can u s u a l l y
use o n l y a l i m i t e d number o f organic
molecules
(e-g.,
acetate
and simple
organic acids)
as s u b s t r a t e s .
These
compounds
are
made
by
microbial
f e r m e n t a t i o n t h a t breaks a p a r t t h e more
complex o r g a n i c molecules i n S p a r t i n a
r o o t s and rhizomes.
Anoxic decomposition i s slower t h a n
a e r o b i c decomposition.
The underground
l e a c h i n g phase
is
similar
to
that
aboveground, b u t t h e subsequent phases a r e
slower. A f t e r 2.5 y e a r s , l e s s t h a n 20% o f
the
original
litter
remained
in
be1 owground f i e l d experiments i n Great
S i p p e w i s s e t t S a l t Marsh (Val i e l a e t a1 . ,
unpubl . data).
These r e s e a r c h e r s a1 so
found t h a t be1 owground 1 it t e r e n r i c h e d i n
nitrogen
decayed
more
rapidly
than
u n e n r i c h e d 1 it t e r i n c o n t r o l experiments.
T h i s i n d i c a t e s t h a t n i t r o g e n 1i m i t a t i o n
p l a y s a r o l e i n a n o x i c decomposition i n
s a l t marshes. There a r e o t h e r d i f f e r e n c e s
from aboveground decomposition:
1ig n i n
decomposes p o o r l y i n anoxi c c o n d i t i o n s ,
and f u n g i a r e n o t a c t i v e i n t h e absence of
oxygen.
The a c t u a l amounts o f decomposition
t h a t proceed v i a t h e s e v a r i o u s paths are
n o t v e r y w e l l known. The g r e a t e r p a r t of
underground
production
is
probably
decomposed t h r o u g h t h e f e r m e n t a t i o n and
s u l f a t e r e d u c t i o n pathways (Howes e t a l .
1984). S u l f a t e reducers a r e n o t e f f i c i e n t
a t converting nutrients i n t o microbial
c e l l s and t h e carbon t o n i t r o g e n r a t i o of
anoxic 1 i t t e r i s about 45: 1 a f t e r 1 y e a r
20: 1 f o r
aerobically
compared
with
Thus, i n t h e former
decompos irig 1it t e r .
case, about h a l f o f t h e n i t r o g e n has been
l o s t t o t h e sediment p o r e water o r
m i n e r a l ized.
This
lack o f
nitrogen
c o n v e r s i o n i n t o m i c r o b i a l biomass may be
one o f t h e reasons f o r t h e g e n e r a l l y h i g h
n i t r o g e n l e v e l s i n marsh sediments and f o r
t h e e u t r o p h i c n a t u r e o f s a l t marshes s i n c e
t h e w a t e r o o z i n g o u t o f t h e mud i s h i g h i n
nitrogen.
Less t h a n 3 g C/m2/yr
is
accounted f o r by t h e d e n i t r i f i e r s i n Great
S i p p e w i s s e t t S a l t Marsh (Kaplan e t a l .
1979), because t h e r e i s n o t a l a r g e supply
of n i t r a t e a v a i l a b l e t o t h e deni t r i f i e r s .
Net methane l o s s t o t h e atmosphere i s
l e s s t h a n 4 g C/m2/yr (Howes e t a l . 1985),
which
is
less
than
1% o f t o t a l
decomposition.
Methane l o s s has been
i n c r e a s e d 2.5 t i m e s by p o i s o n i n g s u l f a t e
reducers w i t h molybdate (Howes e t a l . ,
unpubl. d a t a ) .
T h i s i n d i c a t e s t h a t more
methane i s produced i n t h e marsh t h a n i s
l o s t t o t h e a i r , b u t i t i s consumed by
s u l f a t e reducers.
Recent measurements from t h e Great
S i p p e w i s s e t t S a l t Marsh i n d i c a t e t h a t
decomposition v i a r e s p i r a t i o n w i t h oxygen
of
ha1 f
accounts
for
approximately
e s t i m a t e d underground p r o d u c t i o n (Howes e t
a l . 1984).
But since a substantial p a r t
o f t h e s a l t marsh p r o d u c t i o n i s t o o f a r
underground t o be reached by oxygen, a
major f r a c t i o n o f t h i s i s decomposed
through t h e s u l f a t e r e d u c t i o n pathway.
5.3
NUTRIENT C Y C L I N G
5.3.1.
Ni troaen
The n i t r o g e n c y c l e i s o f g r e a t
importance t o t h e e c o l o g y o f t h e marsh.
N i t r o g e n c l e a r l y c o n t r o l s a wide v a r i e t y
of
marsh processes.
The
level
of
a v a i l a b l e n i t r o g e n and i t s uptake by t h e
p l a n t s determines t h e p r o d u c t i v i t y of t h e
marsh.
The
more
nitrogen
that
is
a v a i l a b l e , t h e g r e a t e r t h e percentage of
grasses t h a t s e t seed.
The r e l a t i v e
abundance o f t h e grasses on t h e marsh a l s o
to
be determined b y n i t r o g e n
seems
availability.
S a l t marsh a l g a e a r e more
p r o d u c t i v e when t h e i r n i trogeri s u p p l y i s
increased i n t h e s p r i n g ;
i n summer,
increased n i t r o g e n suppl i e s enhance t h e
growth o f t h e marsh grass and a l g a l
p r o d u c t i o n i s reduced due t o shading by
t h e grass canopy.
Marsh h e r b i v o r e s a r e a1 so n i t r o g e n
l i m i ted: t h e more n i t r o g e n i n t h e i r food,
t h e h i g h e r t h e i r p r o d u c t i o n . For example,
i n s e c t s are more abundant i n p a r t s o f t h e
marsh where t h e grass has a h i g h e r
nitrogen content.
Those p a r t s o f t h e
niarsh are a l s o much more a t t r a c t i v e t o
geese and v o l e s .
The f o o d q u a l i t y o f s a l t marsh
d e t r i t u s i s also a f f e c t e d by n i t r o g e n
availability.
S a l t marsh d e t r i t u s i s n o t
a v e r y n u t r i t i o u s food f o r animals.
Its
carbon t o n i t r o g e n r a t i o (C/N) v a r i e s from
20: 1 t o 60: 1 w h i l e p h y t o p l a n k t o n , p r o t e i n ,
and b a c t e r i a have values t h a t range from
4 . 5 : l t o 6: 1. Since animals r e q u i r e a C/N
ratio
of
about
17:l
for
minimal
maintenance, n i t r o g e n c o n t e n t i s o f g r e a t
importance i n t h e d e t r i t u s c y c l e i n t h e
marsh.
When t h e amount o f n i t r o g e n i n
d e t r i t u s was experimental l y doubled, t h e r e
was a f o u r - t o f i v e f o l d i n c r e a s e i n t h e
abundance o f d e t r i t i v o r e s on t h e marsh
s u r f a c e (J. M. Teal, unpubl. d a t a ) , b u t no
change i n t h e abundance o f animals l i v i n g
i n t h e bottoms o f t h e marsh creeks ( W i l t s e
e t a1 . 1984). There i s some evidence t h a t
t h e f i s h i n t h e marsh grow f a s t e r i n t h e
f e r t i l i z e d p a r t s o f t h e marsh t h a n t h e y do
i n c o n t r o l areas, b u t t h e response i s n o t
as c l e a r as i t i s w i t h e i t h e r t h e p l a n t s
o r marsh s u r f a c e d e t r i t i v o r e s (Connor
1980).
Nitrogen
enrichment
affects
the
spacing o f grass stems.
I n t h e more
p r o d u c t i v e p a r t s o f t h e marsh, t h e stems
are t h i c k e r b u t f a r t h e r
apart than
elsewhere.
Hartman e t a l . (1982) r e p o r t
t h a t i n t h e h i g h l y p r o d u c t i v e creek banks,
about 40% o f t h e s u r f a c e area l i e s between
t h e grass stems, w h i l e i n t h e l e s s
p r o d u c t i v e low marsh t h e space between t h e
stems i s o n l y h a l f as g r e a t .
The marsh
f i s h e s are much more s u c c e s s f u l i n h u n t i n g
among these w i d e l y spaced stems t h a n t h e y
a r e among t h e c l o s e l y spaced stems i n t h e
less productive parts o f the marsh (Vince
e t a l . 1976).
Nitrogen also has an e f f e c t on t h e
decomposers i n the marsh. Decomposition
rates were found t o be s l i g h t l y increased
i n areas with added nitrogen ( V a l i e l a e t
a l . 1984).
The difference i s small and
only means t h a t i n the less productive
parts o f the marsh the d e t r i t u s l a s t s a
1it t l e longer since the normal decomposi t i o n process eventually does away w i t h
almost a l l of the organic matter t h a t i s
produced i n the marsh.
The following discussion of the marsh
nitrogen cycle draws mostly on data from
Great Sippewissett S a l t Marsh (Val i e l a and
Teal 1979). This i s the only s a l t marsh
anywhere f o r which there i s a complete
published nitrogen budget a t the present
time (Table 5). Except when i d e n t i f i e d as
measured i n low marsh, the data r e f e r t o
the nitrogen budget f o r t h a t e n t i r e marsh
including the regularly flooded i n t e r t i d a l
marsh and also high marsh, pannes, sand
f l a t s , and creeks.
Great Sippewissett
Salt Marsh i s enclosed behind a b a r r i e r
beach and interacts w i t h the bay through a
singlo channel i n which many o f t h e
fl~easurements of exchange were made. The
exchanqos between the d i f f e r e n t p a r t s of
the marsh were not measured, so the
f 1ooded
marsh
cannot
be
reg111 a? I y
discilssed i n i s o l a t i o n .
N i t r o g e n i s s u p p l i e d t o t h e marsh by
b o t h p h y s i c a l and b i o l o g i c a l processes
(Figure 21).
Ground w a t e r and f l o o d t i d e s
b r i n g n i t r o g e n i n t o t h e marsh system; ebb
t i d e s remove it. Ift h e r e i s s i g n i f i c a n t
r i v e r o r stream f l o w i n t o a marsh, t h i s
can be an i m p o r t a n t source o f nitrogen.
B a c t e r i a and b l ue-green a1 gae f i x nitrogen
gas from t h e a i r and d e n i t r i f y i n g b a c t e r i a
c o n v e r t t h e n i t r o g e n i n n i t r a t e back to
gaseous form.
P l a n t s and micro-organisms
b u i l d n i t r o g e n , m o s t l y from ammonia and
n i t r a t e , i n t o o r g a n i c compounds such as
amino a c i d s , p r o t e i n s , and nucleotides.
Some o f t h e e x p o r t from t h e marsh i s i n
t h e form o f o r g a n i c m a t t e r (as organic
detritus,
plankton,
and
animals)
containing
these
nitrogen
compounds.
By f a r t h e l a r g e s t f l u x e s o f nitrogen
b o t h i n t o and o u t o f t h e marsh are those
c a r r i e d i n t h e t i d a l flows.
I n Great
S i p p e w i s s e t t S a l t Marsh, o v e r 70% o f the
i n p u t s and n e a r l y 90% o f t h e outputs were
c a r r i e d b y t h e t i d e s (Table 5). The t i d a l
creeks c a r r y i n g t h i s w a t e r occupy about
34% o f t h e t o t a l marsh area, a s i t u a t i o n
s i m i l a r t o t h a t i n o t h e r mature marshes
t h a t have c o m p l e t e l y f i 1 l e d t h e i r basins.
The l a r g e s t p a r t o f t h e n i t r o g e n exchange
i s i n t h e f o r m o f d i s s o l v e d organic
n i t r o g e n (DON) w h i c h d i d n o t change much
i n concentration
between
i n f l o w and
outflow
(Table
6).
Because
the
c o n c e n t r a t i o n d i d n o t change measurably,
i t i s assumed t h a t most o f t h i s organic
Table 5. Nitrogen budget f o r Great Sippewissett S a l t Marsh. Values a r e i n
kg N / Y ~f o r the e n t i r e marsh o f 48.3 ha ( V a l i e l a and Teal 1979, and unpubl.
data).
--"Source
-"-
Inputs
-
Rain
Ground water
Nitrogen f i x a t i o n
a1 gae
bacteria (rhizosphere)
Tidal exchange
Oeni t r i f i c a t i o n
Sedimentation
Other (gul I s , clams)
300
2,980
26,200
Outputs
-
--
31,600
3,490
1,295
9
26
N e t exchanges
3,280
5,350
3,490
1,295
in
out
out
out
17 o u t
little exchange of nitrite
nitrate (NO:\) (Figure 22).
(NO,)
or
nitrogen is not very active biologically
and does not contribute much to the
nitrogen cycle of either marsh or estuary.
Ground water contributed about 12.5 g
N/m*/yr to Great Sippewissett Salt Marsh.
Some
marshes
have
significantly
less
ground water flow than Great Sippewissett
Salt Marsh, although in most marshes this
has not been measured.
Flax Pond Marsh on
Long Island has a lower salinity than Long
Island Sound, which probably indicates
ground water intrusion.
There is likely
to be a
substantial
contribution of
nitrogen from the ground water.
Other
salt marshes along the southeastern coast
may receive nitrogen from the river flow
entering the estuaries.
This amount has
been estimated to be about 3 g N/m*/yr to
southeastern salt marshes (Windom et al.
1975).
At Great Sippewissett Salt Marsh,
there was about half as much nitrogen in
rainwater as in the ground water.
Only
about 1% of the nitrogen input came from
direct rainfall and 16% came from ground
water flow (Valiela et al. 1978b).
This
resulted from the much larger area of the
watershed in comparison to that of the
marsh itself.
Dissolved inorganic nitrogen (DIN),
on the other hand, exhibits significant
changes in concentrations with time and
tide--changes which have implications for
both marsh and estuary.
The major part of
the inorganic nitrogen is in the form of
ammonium ion (NH,).
For most of the year
ammonium concentrations were similar in
the incoming and outgoing tides in Great
Sippewissett Salt Marsh and there was
As sea level rises, the surface of a
healthy salt marsh maintains its relative
tidal level by accumulating sediments from
the water and peat from the grasses.
nitrogen is
Organic
buried in
these
sediments until it is deep enough to be
beyond the reach of roots.
This loss was
a small quantity in the nitrogen budget
for the marsh, amounting to about 1% of
the nitrogen contained in the upper 15 cm
Sedimentation
Figure 21. Nitrogen fluxes between a salt
marsh and surroundings.
T a b l e 6 . Annual nitrogen exchanges for Great Sippewissett Salt Marsh.
values are in kg/yr (Valiela and Teal 1979, and unpubl. data).
Form
NO3
NH4
DONa
Particulate N
N2
Input
3,420
3,150
19,200
6,750
3,280
output
1,220
3,550
18,500
8,200
3,490
adissolved organic nitrogen.
37
Net change
2,200
-400
700
-1,460
-210
All
Net change/input
64%
-13%
4%
-22%
-6%
roots of Spartina (Teal et al. 1979).
relatively
this
is
a
While
small
percentage, it is very important to the
it occurs just at the site
pl ant b e c a u s e
of uptake and, therefore, is most readily
the
for
plant's
available
use.
Denitrification is the microbial process
nitrogen to the air as
that returns
There are several smaller
nitrogen gas.
components
biological
of the budget:
organic nitrogen is transported out of the
marsh by shellfish harvesting by humans or
by fish swimming out of the marsh; organic
nitrogen is transported into the marsh by
feces deposition by birds, such as gulls,
that have fed outside the marsh but come
there to rest.
available to
and
sediment
marsh
of
Anoi$zr
minor
component
sartina roots.
of the total nitrogen budget was the Toss
of ammonia to the air from the marsh
surface.
Nitrogen is fixed from the atmosphere
bY nitrogen-fixing bacteria associated
with the roots of the grasses and by algae
growing on the surface of the marsh.
between
fixation
nitrogen
Rates of
different parts of the marsh vary as much
as
between different marshes (Valiela
1982).
About 10% of the nitrogen input
fixation
nitrogen
from
result
may
primarily by the bacteria associated with
changes in the nitrogen
Seasonal
cycle at Great Sippewissett Salt Marsh
gave us insight into the processes which
controlled it.
At the beginning of the
most
active
growing
season
the
for
grasses, there was substantial import of
ammonium from the bay to the marsh (Figure
22).
At that time the Spartina needed
nearly 40 kg N/day.
The ground water
input of inorganic nitrogen amounted to a
little less than 10 kg N/day; the tides
supplied about 8 kg N/day to the marsh.
The resulting deficit of over 20 kg N/day
had to be made up by processes within the
marsh itself.
A little later, in August,
when the plants had matured, flowered, and
were beginning to become senescent, as
much as 12 kg N/day of ammonium were
exported from the marsh to the bay via the
tides.
Not only was most of the ground
water nitrogen not being intercepted by
the marsh, but the plants were leaching
nitrogen into the water.
Figure 22.
Net exchanges of inorganic
nitrogen between Great Sippewissett Salt
Marsh and Buzzards Bay (top) and the bay
and ground water (bottom).
Heavy black
bar
indicates
period of
Spartina
senescence.
The bottom graph compares the
input of nitrate from ground water to the
summed -tota) exchanges of all forms of
'tnorganlc nitrogen by tides (Valiela and
Teal 1979).
38
Denitrification in a New England
marsh, like nitrogen fixation performed by
bacteria, varies in response to the marked
seasonal temperature changes (Figure 23).
Denitrification rates were highest (5 mg
creek bottoms which
N/m'/hr) in tidal
total
carry
the
out
most
of
denitrification for the entire marsh. The
~~~~:nte~ motytSof Ofthe ""reema~~r$
denitrification. When denitrification for
the marsh as a whole is compared with the
input of nitrate from ground water and the
export of nitrate to the bay, it is
apparent that nitrate is exported only
during those seasons when denitrification
During the
is at a minimum (Figure 23).
warm weather, most of the nitrate is
interC;iFEf and denitrified upon entering
probably in
the
anoxic
the
Sediments oi the creek bottoms.
little difference between the amounts
entering
and
leaving
the
marsh.
Examination of the values controlled by
biological processes show some interesting
aspects of biological activity within the
marsh system.
For example, the values for
nitrogen fixation and denitrification are
approximately equal.
The measured values
for denitrification in the muddy creek
bottoms are about equal to the net input
of nitrate (Howes et al., unpubl. data).
There
is
a
much
smaller
amount of
denitrification on Spartina-covered areas,
the nitrate for which is probably supplied
by oxidation of nitrogen compounds at the
surface of the mud.
If one adds up all
the sources
of nitrogen available to
support marsh grass growth (i.e.,
net
input of ammonia, nitrogen fixation, net
input of DON) and subtracts from this the
net losses to the sediments, the total is
about
1,600 kg N/yr.
But the total
production of marsh grass requires nearly
9 tons of nitrogen per year. Much of this
is supplied by cycling within the very
large "pool" within the sediments, which
various
balances
the
demands.
The
cycling is mostly due to the activities
Animals play a smaller
of microbes.
excreting
through
feeding
and
role
thereby
nitrogen
within
the
marsh,
microbial
rates
of
stimulating
the
activities.
For example, marsh mussels
deposit as pseudofeces much of what they
filter out of the water and thus create
a substrate on which microbes are active
Fiddler
(Jordan and Valiela 1982).
crabs and snails turn over the surface
layers of the sediments and stimulate
microbes.
The overwhelming portion of nitrogen
exchange is driven by physical forces,
with only 15% being entirely biological in
The salt marsh is
nature (Table 5).
setting:
driven by its physical
the
and the anoxic
tides, the salty water
sediments, which determjne the character
of the living things that can survive
But the biological components are
there.
the ones with which we are primarily
The living organisms determine
concerned.
how the marsh looks and persists and in
what ways it is important to us.
Another way of
looking at
the
nitrogen budget is to examine the balances
for the various forms of nitrogen (Table
Unfortunately, we can only lump all
6).
of the dissolved organic nitrogen together
as one number in this table.
Table 6
emphasizes that although the total amount
of DON is very large, there is relatively
ANNUAL
TOTALS (kg yr-‘1
* Gross denitriflcation
3016
0 Export of N03-N by tide
941
0 Import of NO,-N through ground water
2921
16
of Great
role
To
sum
up
the
Sippewissett Salt Marsh as an example of
New England marshes, one can say that if
the marsh were not there:
(I) more
inorganic nitrogen would reach coastal
waters, (2) the nitrogen would be in the
more oxidized form (NOs rather than NH4),
(3) nitrogen would enter coastal waters
the
year
throughout
more
uniformly
rather than principally as a pulse in
autumn,
and (4) there would be less
nitrogen exported as particulate organic
nitrogen (detritus and living cells),
the form of nitrogen that can be consumed
directly by coastal animals such as filter
feeders.
MONTH
Figure 23. A comparison of nitrate input
from
ground water,
nitrate export by
and denitrification within Great
Sippewissett Salt Marsh (Valiela and Teal
1979).
tides,
39
-
5.3.2.
Phosphorus
Phosphorus is an essential element
for organisms and often limits production
on land and in freshwater, though rarely
It enters marshes
in coastal waters.
bound to sediment particles and dissolved
Experimental
in ground and tidal waters.
alone had no
additions of phosphorus
effect on marsh production, though when
added to marsh plots already receiving a
phosphorus did
high dose of nitrogen,
Two
increase plant growth (Teal 1984).
generalizations can be made about the
relationship between phosphorus and salt
marshes (see Nixon 1980 for a recent
review):
(I) marshes seem to act as
phosphorus sinks, accumulating phosphorus
in their sediments; (2) marsh sediments
lose some of their phosphorus both from
pumping by Spartina and from diffusion,
and may well serve as a source for
reactive phosphorus to the surrounding
(Nixon
1980).
Nitrogen is
waters
generally the factor thought to limit
plant production in coastal oceans areas;
however, in situations where phosphorus is
limiting to plankton production (such as
in an enclosed lagoon w her e an active iron
cycle may remove phosphorus from the water
as ferric phosphate), a neighboring marsh
could support productivity by supplying
phosphorus from marsh sediments.
5.3.3.
Sulfur C&
--l___l
f3ecause of the abundant supply of
seawater,
sul fluis
W?VE!r‘
sulfur in
limiting to
marsh
organisms.
This
abundance is exemplified by one of the
characteristic odors of the salt marsh:
sulfur
dimethylsutfide,
a
reduced
compound.
Hydrogen sulfide, which is
the
obvious as
rotten
smell
egg
occasionally
apparent (especially
on
disturbed
attest5 to
marshes),
also
sulfur's abundance.
Hydrogen sulfide is
toxic to higher plants, and even those
plants that grow in wetlands (e.g. rice,
Spartina) are harmed when their tolerance
1s exceeded (Joshi et al, 1975).
Howarth (1980) measured the annual
sulfate
in Great
cycle of
reduction
Sippewissett Salt Marsh, and found the
same sort of seasonal cycle as was evident
in other microbial annual cycles except
that the maximum sulfate reduction rate
There was
was displaced towards the fall.
a time lag between maxirnum temperature and
The
maximum sulfate reduction activity.
substrate for sulfate reduction is organic
matter from decaying or leaking roots and
Most of these die in the fall
rhizomes.
which explains the increased reduction at
this time.
sulfide produced is
Some of the
fairly rapidly bound up as pyrite, a form
in which the sulfur is not toxic to the
But the
higher plants (Howarth 1980).
to oxidize
ability of Spartina roots
is the principal
sulfide in sediments
lives in an
which it
mechanism by
have
that would otherwise
environment
sulfide.
levels of
hydrogen
toxic
Spartina also has the ability to take up
dissolved sulfide and apparently oxidize
it enzymatically within the roots, another
possible mechanism for resisting toxicity
(Carlson and Forrest 1982).
The amount of energy available to
organisms through sulfate reduction is
very much less than is available through
oxidation of the same organic compound
For example, the oxidation
with oxygen.
of glucose in the presence of oxygen
provides a little over 39 kilojoules per
gram (kJ/g) of glucose carbon; oxidation
via the sulfate reduction cycle provides
The 31 kJ/g difference
only about 8 kJ/g.
does not, of course, disappear. Since the
organic matter is oxidized all the way to
carbon dioxide and water, there is no
The
matter.
organic
in
left
energy
"missing" energy, as one would suspect, is
This sulfide
locked up in the sulfide.
diffuses to the oxidizing layers in the
is
then
it
where
marsh
sediments
chemically or by
reoxidized (either
sulfide-oxidizing organisms) to produce
The energy produced by this
sulfate.
reaction is over 30 kJ/gC, the difference
between what was available to the sulfate
been
have
would
what
and
reducers
available had the organic matter been
The
oxidized by an aerobic organism.
oxidation of sulfide may be incomplete and
produce thiosulfate or other intermediate
Correspondingly, less energy is
products.
yielded at each step in the process, but
the sum of energy from all the steps will
remain about the same.
A I though th i s much energy is {Dade
available by the oxidation of sulfide, it
is not very efficiently captured by the
marsh microbes. Only recently has it been
shown
that Begyiatoa,
a common marsh
microbe that oxidizes sulfide (Figure 24),
can capture any significant part of the
available
energy (Nelson and Jannasch
1983).
Most of the sulfide oxidirers are
bacteria; however, these may live within
oryani sms.
higher
.The bacteria oxidize
sulfide as a source of energy and fix
carbon, making organic matter from carbon
dioxide.
The host animals provide the
bacteria a place to live and, in return,
derive food from them.
This symbiotic
association has been found in mud-flat
worms in North Carolina (Ott et al. 1983)
and clams living in Massachusetts eel
and
has
grass beds (CaveflalK$l
1983),
recently been discovered to he the basis
for t i‘t^e occurring around the deep-sea
vents (Cavanaugh et al.
1981).
It is
reasonable to
that
further
expect
investigations
the
same
will
reveal
symbiosis in borne organisms, such as worms
living in marsh sediments.
and clams,
5.3.4. Carbon
--II_
discussed
is
The
carbon
cycle!
primarily in sections 5. I (Productivity)
Two further
arid 5.2 ( D e c o m p o s i t i o n ) .
points cannected w i th the l;lll fur- cycle
shed light on processes involving carbon
within the marsh.
This microbe is
Begyiatoa growing at the low edge of the salt marsh.
Figure 24.
The color is due to grains of
visible as tiny white threads on the marsh surface.
Photo by J.M. Teal, Woods
sulfur that result, from the microbe's oxidation of sulfide.
Hole Oceanographic Institution.
41
Its abundance in samples of
on earth.
and
can be
analyzed
matter
organic
compared to a standard called PDB Chicago,
cephalopod (a
fossil
which
is
a
The analytical results are
belemnitef.
fraction of
d13C
the
expressed as
carbon-13 compared 'to carbon-12 in the
sample divided by that in the standard
minus one times 1000:
The first is that estimates of total
sediments
marsh
from
production
co2
indicate there is little loss of reduced
All of the final
sulfur from the marsh.
decomposition processes produce carbon
dioxide as an end product, so the total
produced is a measure of total
CO2
Oxygen is consumed when
decomposition.
the decomposition is via respiration and
also
when
the decomposition products
sulfides
and
methane)
are
(e.g.,
So if the CO2 produced is
reoxidized.
balanced by the O2 consumed, there is
little net loss of carbon produced from
the system (Figure 25; Howes et al. 1984).
The CO2 production is higher than O2
consumption early in the season because
reduced
sulfur
compounds
are
being
accumulated; but later the relationship is
reversed as
the
reduced
sulfur is
reoxidized at the mud surface,
d13C
I
C/lZC standard
Negative values come from samples in which
there is less 13C than there is in the
Organisms should have less 13C
standard.
in their tissues than is present in their
carbon source because it takes a little
more energy to build a compound with
carbon weighing 13 atomic units than it
takes to build with carbon weighing only
12 units.
The bicarbonate in seawater has
d13C of about 0 ppt; CO2 in the atmosphere
has a value on the order of -7 ppt.
Spartina and other plants with the C-4
photosynthetic pathway (see Sect. 3.1)
Most
have values from -12 to -14 ppt.
temperate terrestrial plants, which have
the C-3 pathway, have values of -22 to -34
Phytoplankton range from about -20
PPt.
to -30 ppt, benthic diatoms in the marsh
from about -15 to -18 ppt.
The second point is that carbon
isotopes, especially when combined with
sulfur isotopes, can tell us something
about the marsh food web.
Carbon-13 is a
natura 1 stable isotope of carbon present
in sma 11 amounts in all carbon compounds
Figore 25. Annual cycle of carbon dioxide
production and oxygen consumption in Great
Sippewissett
Salt Marsh.
The total
production and consumption are equal. The
offset between the curves indicates the
accumulation of sulfide when decomposition
(as measured by COe) exceeds oxidation
early in the year, and the reverse later
in the season when accumulated sulfides
are oxidized (Howes et al. 1981).
42
One would expect animals to have a
d13C value that reflects the food that
they
eat
some
minor
(subject
to
constraints); for example, animals that
feed principally upon Spartina detritus
might be expected to have d C values of
-12 to -14 ppt.
Haines (1976a,b) and Dow
(1982) found this to be true for organisms
like the marsh grasshopper, which feeds
upon living Spartina.
A similar value was
found in some of the omnivorous crabs in
the Georgia marshes.
These crabs are very
close to Spartina in the food web and at
times feed directly on decaying Spartina
leaves.
The grass shrimp in the Georgia
marshes also have values that are similar
to Spartina, which is consistent with a
diet of
heteroclitusW v~~~~~tu",;gge,',"nd~~~~
their carbon comes from a mixture of
Spartina and benthic algae carbon (via the
animals that form the main part of their
Prey) (Kneib et al. 1980).
Other Georgia marsh animals have d13C
values that are considerably lower, much
clew to the values for phytoplankton,
benthic diatoms, and terrestrial C-3 type
plants than they are to Spartina. Haines
(1978) suggested that these carbon isotope
data support the idea that particulate
organic detritus in Georgia estuarine
waters comes from offshore phytoplankton
production rather than from the marsh, and
that the marsh is actually accumulating
organic matter from offshore phytoplankton
production rather than exporting detritus
to the estuaries.
Dow (1982) reviews the
difficulties in using carbon isotopes
alone to determine the origin of the food
of marsh organisms.
43
Peterson et al. (1984) have included
an analysis of the sulfur isotope, 34S, in
their interpretation of food webs in Great
Sippewissett
Marsh
Salt
for
added
resolution
in determining food sources
because, compared to plankton, S artina is
depleted in 34S.
Peterson et %84)
al.
found that the mud
snails Ilyanassa
obsoleta and Fundulus heteroclitus were
verv close to Soartina in both carbon and
sulfur i sotopes.Marsh mussels, Geukensia
demissa,
varied in isotopic composition
showing that they fed principally on
phytoplankton near the marsh entrance to
the bay and about equally on Spartina
detritus
phytoplankton
in
and
the
innermost reaches of the marsh.
II
CHAPTER
8.1
6.
SALT
MARSH VALUES AND I N T E R A C T I O N S
extrapolated to the estuary, the author's
data actually referred only to export from
the grassy portions of the marsh to the
marsh creeks.
VALUES
For some decades, salt marshes have
been considered or known to be valuable
They are
for a number of reasons.
aesthetically pleasing for their open
coastal spaces and attractive expanses of
They are also valuable as
grasses.
habitat for shore birds and waterfowl, and
as refuges and nursery areas for many
kinds of small and young fishe s; the se
the
with
associated
values
are
exceptionally high productivity of the
regularly flooded intertidal wetlands.
Odum (1980) summarized evidence that
the export does go further than the marsh
creeks and that there actually is an
Hopkinson
outwelling to coastal waters.
and Wetzel (1982) showed that the nutrient
and oxygen fluxes in a Georgia coastal
Odum's
supported
ecosystem
benthic
Direct measurement has shown
conclusion.
the same general level of export from
Great Sippewissett Salt Marsh as the 1962
marsh.
Georgia
the
from
estimate
Particulate carbon (detritus) equivalent
to 40% of the aboveground production is
exported from Great Sippewissett Salt
Marsh to Buzzards Bay (Valiela and Teal
Prouse et al. (1983) indicated a
1979).
sizable export of plant material to
estuarine waters from marshes in the Bay
Schwinghamer et al. (1983)
of Fundy.
demonstrated that salt marsh detritus is
widely distributed in the upper parts of
the Bay of Fundy. Nixon (1980) concluded
that available data indicate that the
total flux of organic carbon from salt
marshes is between 100 and 200 g C/m*/Yr.
Marshes are valuable to the public as
a whole, to those who harvest fish and
shellfish, and, of course, to those who
own the marshes.
To some owners, the
principal value of a marsh is as a piece
of real estate, which often means they
either fill in the marsh for building or
dredge it for boating.
But, aesthetic
values can also be important for the owner
directly.
For example, in 1965 people in
New England were willing to buy salt
marshes for from $100 to $1,000 an acre
(as much or more than they would have had
to pay for poor farmland) just to acquire
the view, access to the water, or "a place
to fly a kite," with the knowledge that
the buyers could make no other appreciable
use of the "land" (Mass. Reporter 1976).
With these facts in mind, we can look at
the Present situation with regard to those
genera'l values of wetlands.
6.2
MARSH
The structure of a marsh system
Odum et
affects its export-import role.
al. (1979b) have classified marshes into
three types according to their flow and
tidal exchange characteristics. The first
are those in which there is a restricted
tidal flow. The flow may be restricted bY
a long and narrow exchange channel, bY
natural sills with a depositional basin on
the marshward side of them, or by man-made
restrictions such as dikes with culverts
EXPORTS
There is still considerable interest
in the question of outwelling of detritus
In the 1962 description of energy flow i;
a Georgia Salt marsh, Teal estimated
export
from
the
marsh
surface of
approximately
40% of the marsh productivity.
While export estimates were
or bridges with a constricted channel for
The second
the passage of tidal flow.
type includes marshes where the flow is
The third has
more open and unrestricted.
All three types Of
completely free flow.
44
marshes are common along the east coast.
determined by
exchanges
these
The
would be
enhanced by
morphologies
increased tidal amplitude or increased
It seems logical that
freshwater input.
the first type of salt marsh would
normally have restricted export of organic
matter, while the other two would be
characterized by a much greater tidal
export.
exporters when catastrophic events are
considered."
The significance of organic carbon
be considered in the context
of the coastal zone it reaches.
Nixon
(1980) emphasized this, concluding that
the export of organic carbon "may provide
a.
. . significant fraction of the open
water primary production in many areas of
the South . . . but it does not appear to
result in any greater production of . . .
fish than is found in other coastal areas
without salt marsh organic supplements."
Nixon was writing about production on a
regional
local
basis,
On a
basis.
enhancement of production can be important
to the population of a small area.
The
contribution to the total fish catch in
Massachusetts of a small port where all of
the fishing is inshore from small boats
might be almost insignificant. While the
most valuable portion of the State catch
comes from the Georges Bank, that local
catch may be very important to the
citizens of the small port and essential
to their economy. An inshore fishery in
Massachusetts may be marsh- and estuarinedependent even though the offshore fishery
is totally independent of these coastal
Recreational fishing is almost
features.
export iwit
The age of a marsh may have a
significant influence on its behavior as
an exporter of organic detritus. A marsh
eventually fills its basin to the high
tide level and acts as a sediment sink
only in relation to the rise in sea level.
for example, the Great Sippewissett Salt
particulate
exports
suspended
Marsh
organic carbon through the marsh creek to
Buzzards Bay while the younger Flax Pond
net import of suspended
Marsh shows
organic
carbon from Long
particulate
Houghton and
Island Sound (Table 7).
Woodwell (1980) indicate that there is a
large export of litter in the form of dead
Spartina stems from Flax Pond, principally
at times of storms. As Dow (1982) points
out, "Even systems which import organic
based on sampling
carbon to marshes,
can become
cycles,
of selected tidal
T a b l e 7.
(Valiela
Comparison of age and properties of two northeast United States
1982).
Flax Pond
Marsh
Age and properties
Age of marsh (yr)
Indicators of maturity:
Average accretion rate (mm/yr)
Expanding part of marsh
Established part of marsh
(Accretion/net production) x 100% in terms
of carbon
% of area non-vegetated
% of area covered by tall Spartina alterniflora
Average aboveground standing crop of
S. alterniflora (g/m2)
% of area in high marsh
Number of higher plant species
45
180
1.5-37
2-6.3
Salt, marSheS
Great
Sippewissett
Marsh
2,000
14
1
37
47
37
5
37
18
975
7
13
350
2";
The interested
arrive in salt marshes.
reader should look at reviews by Giblin
N i x o n (1980), Giblin
et al
(1980),
,
and
Teal
et
al. (1982).
(1982)
and
catch
both
inshore S O
totally
coastal
dependent On
are
economics
features.
There is little doubt that marshes
export organic matter in the form of Young
fish that enter the marshes as larvae,
postlarvae, or juveniles in early summer.
During the warm part of the Year they grow
rapidly, becoming better able to survive
in coastal waters in the autumn (Werme
i9a1). Turner (1977) has shown that there
is a significant correlation between the
area1 extent of subtidal and regularly
vegetation in an
flooded
intertidal
estuary and the size catch of the inshore
shrimp fishery in the Gulf of Mexico.
Successful commercial blue crab fisheries
are associated with salt marshes as are
fisheries (Pomeroy and Wiegert
sport
has been
continuously
level
Sea
rising since the retreat of the PleistoThis regular rise makes it
cene glaciers.
possible to assign approximate dates to
core depths independent of dating the
material in the core itself.
Figure 26 is
a profile of lead found in cores from New
The concentrations inEngland marshes.
creased dramatically toward the surface,
recently deposited
i.e., in the more
This increase began about the
sediments.
time market hunting of shore birds in the
marsh was prevalent and was accelerated
The present
industrialization.
during
high level is correlated to the burning of
leaded gas in automobiles. The high sample value from the Neponset River Marsh
was taken near a major highway (Banus et
A similar profile has been
al. 1974).
(Siccama
and
found in other marshes
These
McCaffrey 1977).
Porter 1972;
that as
all
indicate
studies
marsh
x381).
A timely visit to most salt marshes
along the Atlantic coast will convince a
visitor that the marsh killifish is an
important food source for wading birds and
as such provides the basis for an export
in the form of heron and egret biomass.
In Georgia, the bird biomass similarly
exported may be that of the white ibis
which seemed, in one Georgia nesting area,
to be feeding almost exclusively on grass
shrimp from salt marshes (Teal 1965).
Black ducks feed extensively on Hydrobia
and Melampus from salt marshes.
Canada
geese are very attracted to and take a
significant amount of Spartina production
from salt marshes in Cape Cod (Buchsbaum
et al. 1982).
6.3
POLLUTANTS
AND
% ~3?4xv- G ro und Rio mo ss
MARSHES
0 G re at Slppe wlsse tt Mcrsh
0 Barnstable
6.3.1.
M
Heavy
e t a l s
Marsh sediments act as filters and
tend to accumulate heavy metals.
Most
heavy metals form insoluble sulfides, and
are sorbed onto clays, organics,
and
PrfXZipitdteS Such as iron hydroxides. The
marsh
sediments
have
high
sulfide
ConCedJM.ions SO that the insoluble metal
sulfides tend to be deposited in the
sediments and accumulate there.
As a
result of Several decades of research on
the behavior of heavy metals in salt
marshes,
nluch is now known about what
actually takes place when heavy metals
Marsh
A Neponset RIVW Marsh
based on 91cm/1000yr
se0 level me
60
A
/
7ok
1131
“0
and
Figure 2 6 .
distribution
Lead
concentration in cores from New England
salt marshes (Banus et al. 1974).
46
indtlstrial activity has increased and more
metals have been discharged into the
environment, the levels of the metals in
sediments
have
marsh
also
increased.
At the other extreme, Giblin et al.
(1980) found that cadmium forms soluble
complexes as well as sulfides in seawater.
If the application or supply of cadmium to
the marsh is stopped, it only takes about
2 years for the metal to disappear from
Other metals occupy
the marsh muds.
intermediate positions between lead and
cadmium in their transit through the
Metals such as copper and chromium
marsh.
retained by
marsh
well
fairly
are
such as
zinc pass
metals
sediments;
Where salt
through the system rapidly.
marsh retention of experimentally applied
heavy metals has been examined (e.g., the
Great Sippewissett Salt Marsh), retention
metals is always less
added
the
of
complete than that of the "naturally
arriving metals in the control plots"
(Giblin 1982); perhaps this is because the
metals
are more
arriving"
"naturally
Giblin
effectively bound to particles.
(1982) also stated, "Although in
a
geochemical sense wetlands are sinks for
some
metals,
. . . they may not function
as efficient traps for all metals."
The marsh grasses stabilize sediments
so that they stay in place, become anoxic,
and are thereby able to interact with
In addition,
heavy metals in seawater.
to a varying
grasses take up metals,
Metals are
extent,
from the sediment.
concentrated in leaves and stems of the
When the plant dies and becomes
grass.
detritus,
contained
metals
are
these
exported from the marsh to surrounding
waters.
Giblin (1982) summarizes data
showing that there is little contamination
salt marsh plants by
of
tissues of
arsenic, manganese, mercury, or lead but
by cadmium,
considerable
contamination
zinc, copper,
In o t h e r
and chromium.
words, if salt marsh plants and sediments
are
contaminated with certain
heavily
metals, they can form a long-term source
for contamination of coastal areas.
Plants can also mobilize heavy metals
by oxidizing sediments
turns
soluble
insoluble
sulfide: process
into
which
In
sulfates.
thiosulfates
and
experimental plots at Sippewissett, where
metals were added along with nutrients in
sewage sludge, mobilization of metals from
sulfides was accentuated.
The nutrient
addition stimulated Spartina growth which
accentuated the tendency of Spartina roots
to oxidize sediments.
This urocess both
stimulated mobilization of metals from
sulfides and enabled enhanced plant uptake
of metals applied to the marsh in the
sludge.
The stimulation of production and
sediment oxidation after applications of
this type may be delayed for one or two
seasons so that it may initially appear
that marsh sediments are more efficient at
sequestering or holding heavy metals than
may eventually prove to be the case.
There is additional accumulation of
heavy metals in dead leaves and fresh
detritus formed from marsh plants as they
to decompose (Breteler et al.
begin
Detritus may be enriched to
1981a).
potentially toxic levels by uptake of
metals in the more oxidized surface layers
of marsh sediments or by metals associated
with surface organic layers, just as the
detritus is about to enter the food chain.
If the amounts of metals are small, they
but in larger
have no effect,
will
the marsh products may
concentrations,
reach toxic levels.
There is little data on what levels
of heavy metals are damaging to the marsh
The heavily polluted Berry Creek
itself.
portion of Hackensack Meadowlands contains
that it
could be
much
mercury
so
Such extreme
considered a mercury ore.
cases are rare and considerably lower
In the Great
levels are far more common.
Sippewissett Salt Marsh, there is no
indication that the marsh ecosystem has
been damaged by 12 years of experimental
application of sewage sludge containing
heavy metals at levels nine times higher
used in
sludge
normally
than
those
disposal in uplands (Giblin 1982).
6.3.2.
Organic Contaminants
Though we have some knowledge of the
behavior of heavy metals in a salt marsh,
far less is known about the behavior of
The added sewage
organic pollutants.
sludge in the Great Sippewissett Salt
Marsh studies contained aldrin during the
early years, at which time there was a 50%
reduction of fiddler crab populations in
the treated areas (Figure 27; Krebs et alAldrin was apparently closely
1974).
bound to sediment particles because the
effect was absent as little as 1 m
downstream from the treated area (Krebs
and Valiela 1977). Judging from its lack
of movement in the sediments, al drin
slowly degraded in place just ag\,d~~~
sediments.
anoxic
does in
disappeared from the sludge after its
use was banned in 1972; fiddler crab
pre-aldrin
returned to
populations
levels within about 1 year (Teal et al.
1982).
Information is also available on the
effects and persistence of other organic
pollutants, particularly petroleum. In
1969, 2,000 barrels of No. 2 fuel oil from
the barge Florida were spilled in Wild
Harbor at Westalmouth,
Massachusetts.
In the most heavily affected areas, the
oil persisted in sediments for as long as
12 years, although over 90% of the area
within
about
6
recovered
"Recovery" was measured in terms of i"?,'z;
-_..
of either killing Spartina alterniflora or
preventing its regrowth (Teal and Howarth
Hydrocarbons
from
1983).
the spill
reduced population le ve ls O f
much as aldrin had (Krebs and
Post-spill levels of more
the lighter hydrocarbons per gram of mud
killed both Spartina and fiddler crabs
(Burns and Teal 1979; Hampson and Maul
1979).
The persistence of
oil in the
sediments acted like a predator or trap
the
crabs.
Resident
for
crabs in
contaminated sediments died; in response
to their absence, neighboring populations
expanded into the contaminated areas and
the invading individuals died in turn.
Overwintering young crabs were the most
sensitive, probably because they were in
intimate contact with the contaminated
sediments in their burrows (Krebs and
Burns 1977).
There
are also
studies of the
persistence of hydrocarbons contained in
the sewage sludge added experimentally to
Great Sippewissett Salt Marsh.
These
hydrocarbons are those that survived both
the sewage treatment and sterilization
necessary before the sludge is sold.
Preliminary studies indicate that there is
little buildup of these hydrocarbons in
treated marsh sediments or in untreated
nearby
sediments (J-M. Teal, unpubl.
data); this suggests that the hydrocarbons
must degrade quite rapidly.
6.3.3.
Nutrients
Marshes have been considered for use
In fact, one
in the treatment of sewage.
of the highest economic values placed on
marshes is arrived at considering them in
this context (Gosselink et al. 1973). It
is, therefore, important to know what the
The Great
effects of such use would be.
fertilization
Salt Marsh
Sippewissett
experiments were designed partly to study
these effects and will be used as an
example.
Figure 27. Distribution of fiddler crabs
(& pugnax) in marshes receiving sewage
sludge. The duplicate censuses are shown
extending back from the creek next to one
another for comparison although all were
made in the center of the respective plots
(the size.of the plots is indicated by the
dashed line ) (from data of Krebs and
Valiela 1977).
The experiments of Great Sippewissett
Salt Marsh measured the marsh's retention
of nutrients to evaluate the p o ssib le
eutrophication of the waters associated
48
with the marsh.
Nutrients were added once
every 2 weeks as sewage sludge solids.
During the summer, when the grasses were
actively growing, only 6% to 20% of the
applied nitrogen and 6% to 9% of the
applied phosphate were
lost in tidal
waters (Valiela et al. 1973).
When
nutrients were added as a dilute solution
via a spray irrigation system, about 90%
of both nitrogen and phosphorus were
retained during the growing season; i II
spring and fall, 25% to 40% were lost to
ebbing tidal waters.
nitrogen
A!_ F= 8 plm’lwc?c?k
eqUiV23lU-It
t o
HF
5t-
The biggest effect of the addition of
sewage to
this
salt
marsh
was
the
stimulation of
marsh productivity by
nitrogen.
The increased production of
grasses and algae stimulated production of
the herbivores, detritivores, and the rate
of plant decomposition.
There were also
chanaes i n marsh
structure.
SDartina
altegniflora plants changed from tm
to the tall
form.
The stems became
thicker
and
the
plants
widely
more
spaced--features
characteristic
of the
tall form of the grass that grows on creek
banks (Valiela et al. 1978a). This change
the marsh more
made
the
surface of
accessible to predatory fishes which were
then better able to maneuver between the
more widely spaced stems.
01
I
I
I
I
1
MAY JUNE JULY AUG SEPT
MONYH
Figure 28.
Total nitrogen content of
S artina aiternifiora grown in experiZiGI-+?K-----at Great Sippewissett Salt
Marsh through the growing season. Values
are mean percent dry weight e standard
error.
Added nitrogen also increased the
nitroyen content of grass tissues by about
I% (F‘igure 28; Vince et al. 1981). This
was enough to make the grass leaves more
attractive as food for geese and voles.
In fertilized Dlots. voles cut off as much
as 30% of the Spartina, although they ate
onlv a little of the base of each piece
cut:
Their effects were nearly absent in
control plots (Valiela et al. 1985).
There were even more dramatic increases in
the abundance of insect herbivores in the
The
fertilized
29).
plots (Figure
formed was also enriched in
detritus
nitrogen and increased the production Of
detritivores (e.g., marsh amphipods and
snails) by 2 to 5 times (J.M. Teal,
In Great Sippewissett
unpubl. observ.).
Salt Marsh, even the largest additions of
nitrogen (2.5 g N/m2/week) did not seem to
However, there
damage the marsh system.
was a change in the relative abundance of
(Figure 30).
Spartina and Distichlis.
Spartina alterniflora exhibited maximum
production at relatively low N levels,
while Dist'ichlis spicata continued to
nitrogen
production as
the
increase
addition rate was increased.
Spartina production increased over
time, but there was a relative decrease in
standing crop after the first 4 years
(1985)
Valiela et al.
(Figure 31).
suggested that this decrease may have been
caused by increased water loss by transpiration of the more vigorous plants
led 'in turn to increased soil
which
salinity, or by increased herbivory in
Both processes might
fertilized plots.
also have led to the formation of the
patches of glasswort, Salicornia europaea.
Salicornia is an opportunistic
annual
plant species that became a conspicuous
part of the marsh in the second and third
years following high levels (c. 2iCIyz
kg/ha/yr) of nitrogen addition.
species disappeared as it was selectively
49
8 0 0 r-
0
0
c
LF ,
HF ,
100
I
I
XF ,
200
Annua l Niffo g e n lnp uf g /V/m2
Se wag e sludge u s e d a s f e r t i l i z e r
Cnntrol
P IO I 5
------T-“----~ -------
M
J
J
A
S
Figure 30. Responses of two species of
marsh grass to rates of nitrogen fertiliThe response of Spartina levels
zation.
out at about the dosage used in LF plots,
while the response of Distichlis continues
to rise to the highest rates of N addition
(Valiela and Teal,
used in XF plots.
data, Great Sippewissett Salt
unpubl.
Marsh, MA).
MONTH
l!
1%
le m
Uff
u(ef
at
lodi
#heI
ti
In5
e
get
In:
ipp
etr
IW
If
,bsl
rer
nit
Rbundance of herbivorous
Figure 29.
insects in Great Sippewissett Salt Marsh
control and fertilized plots.
Samples
were taken with a sweep net (data from
Vince 1979).
fed
up*n
by
a
chrysomelid beetle,
~~~ri~~l~l~
m,aritim,a,
and was replaced by
"^_1, /-11-,1
1 nvadr nq rhtaomes from the surrounding
Spartina
32; Valiela et al, 1982).
^- ~-.l_- (Figure
.
Intere'4tinrJly,
the
Salicornia
could
survive at ttw lowest tidal levels because
the beetle does not do well if submerged
too much.
Figure 31. Long-term effects of fertilization regimes on the annual aboveground
peak biomass of Spartina alterniflora.
Standard errors
omitted for clarity.
Control, sewage sludge fertilizers; LF and
HF,,and urea at nitrogen level equal to HF
were started in 1970; XF in 1974; and D+P
All are
at a level equal to HF in 1975.
graphed according to Years from initiation
comparisons
of experiment to facilitate
(Teal and Valiela, unpubl. data, Great
SiPPewissett Salt Marsh, MA).
Probably most New England salt
marshes are polluted to some extent, if
only by pollutants carried in the air and
coastal waters.
In the vicinity of
cities, some are heavily polluted.
But
aside from repeated heavy oiling, digging
and filling-in, salt marshes seem ti
survive most human insults rather well.
In all of the experiments in Great
5 0
system.
Nitrogen first affected plant
production and structure, with consequent
ChfKJ?S
in
arlimal
feeding and plant
decomposition.
The marsh ecosystem itself
seems
not
to
have
suffered
any
degradation.
F i g u r e 3 2 . Distribution of percent cover
between the three major plant types in
Great Sippewissett Salt Marsh regularly
flooded areas between 1976 and 1981.
shows presumed trend of
Dashed line
fertilized plot based on other observaThere has been little change in
tions.
the control area but great changes in
vegetation cover in plots highly enriched
in nitrogen.
clearly
Salt
Marsh, no
Sippewissett
detrimental effects of sewage sludge on
marsh plants were demonstrated, in spite
The
of the heavy metals in the sludge.
observed changes in the marsh ecosystem
were mainly the results of changes in
the
marsh
within
relations
nitrogen
51
On the other hand, some of the marsh
products we are interested in (such as
shellfish), may show elevated levels of
heavy metals in polluted New England salt
marshes.
This certainly affects their
value to human society and reduces it to
zero if the shellfish grounds must be
closed.
If the marsh pollution includes
pathogens,
shellfish
become
may
contaminated with the pathogens and have
to be depurated in cleaner waters to make
them safe for human consumption.
However,
marshes may, in fact, reduce pathogens.
Many details about the function of these
systems and of their reactions to abuse
are still nat well understood.
Marshes
are remarkably resistant and the fact that
a salt marsh is polluted is not a reason
to write it off as lost or even as without
considerable value.
As our knowledge of the functioning
of these rich intertidal grasslands has
grown, we have learned better how to
If we
have
been
them.
appreciate
overenthusiastic about some aspects of
their role in coastal ecology, we have
surely been less appreciative of some of
On balance,
their other characteristics.
salt marshes remain of considerable value
to us and are well worthy of both OUT'
concern and our protection.
Ar nit r o
act iv
Phy d
MS,
1974.
kr. I
J
and i
38:19!
Slum,
Br et elel
and I
enricf
Sparti
12:15!
Meler
Common egret (Casmerodius albus) feeding in salt marsh.
Woods tiole Oceanographic Institution.
Photo by B.L. Howes,
1981b.
exper i
k sac
w ag6
m-
h e ,
LO. 5
miner a
Soil
?achsbau
1982.
Mat e
Mr sh
4 :126-
52
REFERENCES
Armstrong, W.
1967.
The
oxidizing
activity of roots in water-logged soils.
Physiol. Plant. 20:920-926.
Cammen,
L.M.,
E.D.
Seneca,
and L.M.
Stroud.
1980.
Energy flow through the
fiddler crabs Uca
_-- pugnax and U. minax
-TxII
and
the marsh periwinkle
fi ttorl na
irrorata in a North Carolina salt marsh.
Am. Midl. Nat. X03:238-250.
Banus, M., I. Valiela, and J.M. T e a l .
1974.
Export of lead from salt marshes.
Mar. Pollut. Bull. 5:6-9.
1968.
Blum, J.L.
Salt marsh spartinas
and associated algae.
Ecol. Monogr.
38: 199-221.
Carlson, P.R., Jr., and J. Forrest. 1982.
Uptake of dissolved sulfide by Spartina
alterniflora:
evidence
from natural
abundance
ratios.
Science 216:633-635.
Brete ler, R.J., A.E. Giblin, 3.M. Teal,
and I. Valiela.
1981a.
Trace metal
enr ichments
in decomoosina litter of
Spartina
alterniflora.
‘Hquat.
Bot.
12:155-166.
Carpenter, E.J., C.D. Van Raalte, and I.
Valiela.
1978.
Nitrogen fixation by
algae in a Massachusetts salt marsh.
Limnol. Oceanoyr. 23:318-327.
Cavenaugti,
Symbiotic
C.M.
1983.
bacteria in
marine
chemoautotrophic
from
invertebrates
sulfide-rich
habitats.
Nature 302:58-61.
Breteler, R.J., J.M. Teal, and I. Valiela.
198Ib.
Retention
and
fate
of
experimentally
added
mercury
in
a
Massachusetts salt marsh treated with
sewage
sludge.
Mar.
Environ.
Res.
5:211-225.
C.M., S.L.
Gardiner, M.L.
Cavanaugh,
and
3.8.
Jones,
H.W.
Jannasch,
Prokaryotic cells in
Waterbury.
1981.
the hydrothermal vent tube worm Riftia
chemopossible
Jones:
pachyptila
Science 213:
symbionts.
autotrophlc
340-342.
Broome, S.W. ) W.W. Woodhouse, Jr., and
The relationship of
E.D. Seneca. 1975.
mineral nutrients to growth of Spartina
alterniflora in North Carolina: II.
The
effects of N, P, and Fe fertilizers.
Soil Sci. Sot. Am. Proc. 39:301-307.
The effects of
1979.
Chalmers, A.G.
fertilization on nitrogen distribution
in a Spartina alterniflora salt marsh.
Estuarlne Coastal Mar. Sci. 8:327-337.
Buchsbaum, R., I. Valiela, and J.M. Teal.
1982.
Grazing by Canada geese and
related aspects of the chemistry of salt
Waterbirds
marsh
grasses.
Colon.
4:126-131.
The
1979.
Burns, K.A., and J.M. Teal.
West Falmouth oil spill: hydrocarbons in
Estuarine
the salt marsh ecosystem.
Coastal Mar. Sci. 8:349-360.
Snail grazing effects
Connor, M.S. 1980.
on the composition and metabolism of
and
communities
diatom
benthic
fish growth.
effects on
subsequent
Woods Hole Oceanographic
Ph.D. Thesis.
Institution-Massachusetts Institute of
Technology.
The macro-infauna of
Cammen, L.M.
1979.
a North Carolina salt marsh. Am. Mid?.
Nat. 102:244-253.
Connor, M.S., J.M. Teal, and I. Valiela.
The effect of grazing
1982.
by mud
on the
(Ilyanassa obsoleta)
snails
53
structure and metabolism of a benthic
algal community.
J. Exp. Mar. Biol.
Ecol. 65:29-45.
Gallagher,
R.J.
Reimold, R.A.
J.L.,
Linthurst, and W.J. Pfeiffer.
1980.
Aerial
production,
and
mortality,
mineral accumulation-export dvnamics in
Spartina
Juncus
alterniflora
and
roemerianus plant stands in a Georaia
salt marsh. Ecology61:303-312.
I
Cowardin, L.M., V. Carter, F.C. Golet, and
E.T. LaRoe.
1979.
Classification of
wetlands and deepwater habitats of the
United States.
U.S. Fish Wildl. Serv.
Biol.
Serv.
Program
FWOBS-79/31.
103 pp.
Garofalo, D.
1980.
wet1 and
vegetation
channel
migration
Estuaries 3~258-270.
Dacey, 3. W.H.,
and B.L. Howes.
1984.
Water uptake by roots controls watertable movement and sediment oxidation on
short Spartina marsh.
Science 224:
487-489.
Giblin, A.E.
Comparisons of the
1982.
processing of elements by ecosystems.
II.
Metals. Unpubl. MS.
de la Cruz, A.A.
1974.
Primary praductivity
of
coastal
marshes
in
Mississippi,
Gulf Res. Rep. 4:351-3X.
Giblin, A.E., B. Alain, I. Valiela, and
J.M. Teal.
Uptake and losses of
1980.
heavy metals in sewage sludge by a New
England
salt
marsh.
Bot.
Am. J.
67(7):1059-1068.
DeLaune, R.D., R.J. Buresh, and W.H.
Patrick, Jr.
1979.
Relationship of
soil properties to standinuu croD biomass
of Spartina alterniflora in a Louisiana
marsh.
~tZZK?~Ztal
Mar. Sci,
81477-487.
I
Gieselman, J.A.
1981.
Ecology
of
chemical defenses of algae against the
herbivorous snail, Littorina littorea,
in the New England rocky intertidal
community.
Ph.D. Thesis. Massachusetts
Institute of
Technology-Woods
Hole
Oceanographic Institution.
Dow,
U.U.
1982.
Literature review of
organic matter transport from marshes.
NASA 'Tech. Pap. 2022. 74 pp.
Eleuterius I L.N. , and S.P. Mevers.
The influence of
on
stream
tidal
and
morphology.
1974.
Gleason, M.L., and J.C. Zieman.
1981.
Influence of
inundation on
tidal
internal
of Spartina
oxygen
SUPPlY
alterniflora
Spartina
and
patens.
rxuarine Coastal Shelf Sci. 13:47-57,
GaIlagher,
J.L.
1975.
Effect. of an
ammonium nitrate pulse on the growth and
c1ementai composition af natural stands
of sctina
.-~~ alterniflora and Juncus
-~
roernerianus.
?%i"rJ:-'ij161 62:644-648.
-_l_~l__--
Glibert, P.M., M.R. Dennett, and J.C.
Goldman. 1984.
Inorganic carbon uptake
in Vineyard Sound, Massachusetts: I.
Measurements
of
the
photosynthesisirradiance response of winter phytoplankton
assemblages.
J. Exp.
Mar.
Biol. Ecol. In press.
Gallagher, J.L., and F.C. Raiber.
1974.
Primary production of edaphic communities in a Delaware salt marsh.
Limnol.
Oceanogr. 19:390-395.
Gosselink, J.G. 1970. Growth of Spartina
patens and 2. alterniflora as influenced
by salinity and source of nitrogen.
Coastal Stud. Bull. Spec. Sea Grant
Issue No. 5,
Sea Grant Publ. No.
LSU-2-70-010, pp. 97-110.
GaFlagher, J.L. I and F.G. Plumley. 1979.
Underground biomass profiles and productivity in Atlantic coastal marshes.
Am. J. 3ot. 66:151-X1.
Gallagher, J.L., W.J. Pfeiffer, and L.R.
Pomeroy.
1976.
Leaching and microbial
utilization of dissolved organic carbon
from leaves of Spartina alterniflora.
E:stuarine Coastal Marxes. 4:467-471.
Gosselink, J.G., E.P. Odum, and R.M. Pope.
1973.
The value of the tidal marsh.
La. State Univ. Cent. Wetl. Resour. Sea
Grant Publ. 74-03.
54
Hacktwy, 0. P. . and C T i ~ a c i u e y . 191i.
Periodic
t-egressi(:n
analysi
ot
@ ~ ~ l o g i c adla t a .
bljs5.
Araiz. L C , .
22:25-33.
, fi,.
9 1 blkirili
;
v tar P~;u\,P*I~I'II X ~ ~ ~ C ~ 0I9 I Z ~~ .v t * b t~ % f ~
-crkkgera
"-"r3is\tI*r
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b ~ f ? t h t s c ~ > ~ f i ~ t l f ~ ~M,+v
t k
f ; ~ :
t
~
it1
5i.r
:a?
2Q- 35
~
3
Hain@s, E . 8. 1976a. Ruldtion betweep t ~ l p
s t a b l e carbon i s o t o p e compo.,, t ion o f
~ " ~ f l ~ l l ~9
t oA! ~,. ~ : 9 1 1 id, H U r ; l t j u r ) a
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cj
t
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marsh.
k in l i ? 1~ .
Oct>snuqr\.
e%rf i x l t l c ~ t l ~a l i'GA brtrtlobrr ,I
1 a,
21:880-883.
~r\ci
tfw
q ~ a ~ ~ g ~ * s ~ i t \ ~ q fc
h,iy
h 1 1434 - i 9 4 h
Haines,
E.B.
19iGb.
std!,it%
car-bon
t ' a t i o 5 i r l t h e b i o t a , ill) I:, drtd
M~war.tS1, R &
1979
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Massachusetts: imrnptiidte assessmerrt o f
t h e e f f e c t s on marine ir~ver,tehrittes attd
a 3-year s t u d y of yruwth and WCovt?ry o f
a s a l t mar-sh. J. I i s h . Hes. b d s ' d Cgltl
3 5 : 731-744.
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Hackney, O.P.,
and C.T. Hackney.
1977.
Acad.
22:25-33.
Wetzel.
Inm e a s u r e m e n t s
oxygen
of
nutrient
and
10:29-35.
H a i n e s , 1976a.
E . B Relation
.
between the
stable carbon isotope composition of
fiddler crabs, plants, and soils in a
marsh.
salt
Limnol.
Oceanogr.
21:880-883.
Haines,
E.B.
and G.M. Woodwell.
The
Flax
CO:!
and
61:1434-1445.
1980.
between a salt marsh
atmosphere.
Ecology
1976b.
Howarth, R.W.
1979.
in salt marsh metabolism.
Woods
Hole
4:609-616.
Ph.D. Thesis.
Oceanographic
Technology.
EcologicX
processes in coastal and marine systems.
Plenum Press, New York.
Howarth, R.W,
1980.
formation of pyrite
in the surface
sediments
of
salt
a
marsh and its
importance to
ecosystem
metabolism.
Science 203:49-51.
Haines,
B.L.,
a n d
E .Dunn.
L .
1976.
Howarth, R.W., and A. Giblin.
1983.
Growth and resource allocation responses
Sulfate reduction in the salt marshes at
Of Spartina alterniflora Loisel to three
Limnol.
Georgia.
levels
NaCl
in Sapelo
Island,
NH4-N,
Fe,
solution
Oceanogr. 28~70-82.
culture.
Bot.
Gaz.
137:224-230.
1979.
Howarth, R.W., and J.M. 'Teal.
S u l f a t e
r e d u c t i o n
i n
E;Tp;,~oul.. 197iour:;.
24:999-1013.
marsh.
fuel
2
0;
the effects on marine invertebrates
Howarth,
a n d
JTeal.
. M . 1980.
Energy flow in a salt marsh ecosystem:
t h e
r o l e
o f
r e d u c e d
Am. Nat. 116:862-872.
compounds.
J.
35:731-744.
Howes, B.L., R.W. Howarth, J.M. Teal, and
Oxidation-reduction
1981.
I. Valiela.
spatial
potentials in a salt marsh:
patterns
Oceanogr.
Limnol.
production.
26:350-360.
Hartman,
H.F.
18:182-186.
1981.
26:795-800.
56:163-173.
B.L., J.W.H. Dacey, and G.M. King.
Carbon flow through oxygen and
1984.
sulfate reduction pathways in salt marsh
Oceanogr.
sediments.
29:1037-1051.
Howes, B.L., J.W.H. Dacey, and J.M. Teal.
Annual
1985.
Spartina
production of
belowground
alterniflora in a New England salt
Ecology 66(2):595-605.
marsh.
a
N e w
E
i n o r g a n
Howes B.L.,
J.W.H.
and D.D.
Dacey,
Goehringer.
1986.
Factors controlting
the
growth
form
of
?#.%.&
alterniflora:
feedbacks
above-ground
production,
sediment
oxidation, nitrogen and salinity, J.
Ecol. 74: in press.
Jeffries, H.P. 1972.
of a tidal marsh.
17:433-440.
Krebs, C.T., I. Ualiela, G. Harvey, and
J.M. Teal.
1974.
Reduction of field
populations of fiddler crabs by uptake
of
chlorinated
hydrocarbons.
Mar.
Pollut. Bull. 5:140-142.
Lee, C., R. Howarth, and B. Howes. 1980.
Sterols
in
decomposing
Nrtina
alterniflora and the use of ergosterol
in estimating the contribution of fungi
to detrital nitrogen.
Limnol. Oceanogr.
25:290-303.
Fatty-acid ecology
Limnol.
Oceanogr.
Jordan, T.E., and I. Valiela.
1982. A
nitrogen budget of the ribbed mussel
Geukensia demissa, and its significance
in nitrogen flow in a New England salt
marsh.
Limnol.
Oceanogr.
27:75-90.
Linthurst, R.A.
1979.
The effect of
aeration
on the arowth of SDartina
alterniflora
Loise'i.
A m . J?
Rot.
66:685-691.
Joshi, M-M., I.K.A. Ibrahim, and J.P.
Hollis,
1975.
Hydrogen
sulfide:
effects on the physiology of rice plants
and relation to straighthead disease.
Phytopathology 65:1165-1170.
Linthurst, R.A.
1980.
An evaluation of
aeration,
nitroqen,
RH
and factors
affecting Spartina alterniflora qrowth:
a
summary.
Paaes 235-2rii; V.S.
Kennedy, "ed.
Estuarine perspZtives.
Academic Press, New York.
Kaplan, W., I. Valiela, and J.M. Teal.
1979. Denitrification in a salt marsh
ecosystem.
Limnol.
Oceanogr.
24:726-734.
Livingston,
D.C., and D.G.
Patriquin.
1981.
Belowground growth of wina
alterniflora Loisel:
habit, functio=T
biomass
and
r\on-structural
carbohydrates.
Estuarine Coastal Shelf Sci.
12:579-587.
Katz, L.C. 1980.
Effects of burrowing by
the fiddler crab, & pu_gnax (Smith).
Estuarine Coastal Mar. Scl. 11:133-137.
Mann, K.H. 1978.
Nitrogen limitations of
productivity of Spartina marshes and
Laminaria kelp beds.
Pages 363-372 in
R.L.
Jeffries, and A.J. Davy, edc
Ecological
processes
in
coastal
environments.
Blackwell
Scientific
Publications, Oxford, England.
Sulfate reduction in
King, G.M.
1983.
Georgia salt marsh soils: an evaluation
of pyrite formation using 35S and ""Fe
Oceanogr.
tracers.
Limnol.
28:987-995.
Kneib, R.T., A.E. Stiven, and E.B. Haines.
Stable carbon isotope ratios in
1980.
Fundulus heteroclitus (L.) muscle tissue
arid gut contents from a North Carolina
Ecol.
Biol.
Mar.
marsh.
J.
Exp.
46:89-98.
1976.
Vol. 369
Massachusetts Reporter.
p. 512 (369 Mass 512); Northeast 2nd ed.
Vol. 340, p. 487 (340 NE 2nd 487).
A record of the
McCaffrey, R.J.
1977.
and
trace
accumulation of
sediment
metals in a Connecticut, U.S.A., salt
Yale University,
Ph.D. Thesis.
marsh.
New Haven, Conn. 156 pp.
1977. Long
Krebs, C.T., and K.A. Burns.
spill on
Oil
effects
of
an
term
populations of the salt marsh crab, Uca
pugnax. Science 197:484-487.
McGovern, T.A. , L.J. Laber, and B.C. Gram.
Characteristics of the salts
1979.
secreted by Spartina alterniflora Loisel
estuarine
relation to
their
and
Estuarine Coastal Mar. Sci.
production.
9:351-356.
1977.
Valiela.
Krebs, C.T., and I.
applied
experimentally
Effects of
chlorinated hydrocarbons on the biomass
Uca pugnax.
of
crab,
fiddler
the
Estuarine Coastal Mar. Sci.:375-386.
56
i.A.
1979
Mendelssohn,
Nitrogen
fnrtni;
the
ni
metabolism in
hei&
_ _
._
Spartina alterniflora in North Carolina,
Ecology 60:574-584.-Mendelssohn, I.A., K.L. McKee, and W.H.
Patrick, Jr.
1981.
Oxygen deficiency
Spartina
alterniflora
in
roots:
- - metabolism
adapEn
t o
aflOXiL3.
Science 214:439-441.
Mendelssohn, I.A., K.L. McKee, and M.T.
<tresses
Sublethal
Postek.
1982.
Spartina
‘-"--;
alternltlora
controlling
-_~.T~l-_-_"~"_.
-I
223-242
in 8.
productivity.
Pages
GoDal, R.E. Turner, R.C. Wetzei: and
W e t l a n d sCC01
: O<Jj
D.F. 'Whigham, eds.
First
Int.
Proc.
and
management.
India.
Delhi,
Wetlands
Conf.
New
September 1980.
Meyers, S.P., D.G. Ahearn, S. Crow, and N.
1573.
The impact of oil on
Berner.
Pages
marshland microbial ecosystems.
221-228 in 0.G. Ahearn and S.P. Meyers,
Tl%? microbial degradation of oil
eds.
La. State Univ. Cent. Wctl.
pollutants.
Resour. Sea Grant Publ. 73-01.
Meyers, S.P. , D.G. Ahearn, S.K. Alexander,
Pichnia
1975.
w. L..
Cook.
and
~-.0--.".a dominant yeast of the
spartinae,
Indust.
DCZV.
marsh.
Spartiira
salt
-~Mlcroblol. 16:X2-267.
Morris, J.T. 1580. The nitroyen uptake
in
na dlterniflora
kinetics af garti
.__"~.II-X.~Ecology 61:1114-1121.
culture.
1984.
Morris, J.T., and J.W.H. Uacey.
Effects of oxygen on ammonium qtake and
Sp-b3Lr\a
respiration
YW0t
by
alterniflora. Am. J. 13ot. 71:979-985:
1983.
Nelson, D.C., and H.W. Jannasch.
growth of a marine
Chemoautotrophic
Beyyiatoa i n s u l f i d e - g r a d i e n t c u l t u r e s .
Arch. Microbial. 136:262-269.
Nestler, J.
as a cause
Spartina
CoastaT-Mar,
Interstitial salinity
1977.
of ecophenic variation in
Estuarine
alterniflora.
Sci. 5: 707-714.
N e w e l l , R.
The role of detritus in
1965.
the nutriton of two marine deposit
feeders, the prosobranch Hydrobia ulvae
57
Fanning.
and M.E.
1973.
Odum E.P..
of the productivity of
Comparison
alterniflora
and
Spartina
Spartina
cynosuroides in Georgia coastal marshes.
Bull. Ga. Acad. Sci. 31:1-12.
Odum, W.E., P.W. Kirk, and J.C. Zieman.
Non-protein IIi’Cr Ogen compounds
1979a.
associated with particles of vascular
Oikos
32:363-367.
detritus.
plant
Odum, W.E., J.S. Fisher, and J.C. Pickral.
Factors control1 ing the flux of
1979b.
organic
carbon
from
particulate
estuarine wetlands. Pages 69-80 in R.J.
Livingston, ed. Ecological processes in
and marine systems.
Plenum
coastal
Press, New York.
Ott, J., G. R;;-i;r, R. Rieger, and F.
New
mouthless
Enderes.
worms from the sulfide
interstitial
symbiosis with prokaryotes.
system:
Mar. Ecol. (Pubbl. Stn. 2001. Napoli 1)
3:313-333.
Pace, M.L., S. Shimmel, and W.M. Darley.
The effect of grazing by a
1979.
gastropod, Nassarius obsoletus, on the
benthic microbial Communit y of a salt
marsh mud flat. Estuarine Coastal Mar.
Res. 9:121-134.
Pomeroy, L.R., and R.G. Wiegert, eds.
1981.
The ecology of a salt marsh.
Springer-Verlag,
New York.
271 pp.
Ponnamperuma, F.N.
1972.
submerged
soils.
%29-96.
The chemistrv
Adv.
Agron:
Prinslow, T., I. Valiela, and J.M. Teal.
1974.
The effect of detritus and ration
size
on
the
arowth of
Fundulus
heteroclitus
salt
marsh
(L.‘j,
killifish. J. Exp. Mzr.
Biol. Ecol.
16:1-10.
Prouse, N.J., D.C. Gordon, B.T. Hargrave,
C.J.
Bird,
J.
McLachlan,
J.S.S.
Lakshminarayana, J. SitaDevi, and M.L.H.
Thomas.
1983.
Primary
production:
organic matter supply to ecosystems in
the Bay of Fundy.
Bedford Institute
Oceanography
Technical
Report,
Dartmouth, N.S., Canada.
Redfield, A.C. 1972. Develooment of the
New England salt marsh.
'Ecol. Bull.
42:201-237.
Ruber, E., A. Gillis, and P.A. Montagna.
1981.
Production of dominant vegetation
and of
pool
algae on a
northern
Massachusetts salt marsh. Bull. Torrey
B0t . ci ub 108: 180-188.
Delaune.
Patrick, W.H., Jr., anindR.D.
phosphorus
Nitrogen
1976.
utilization by Spartina alterniflora in
Barataria
marsh in
Bay,
salt
a
Estuarine Coastal Mar. Sci.
Louisiana.
4:59-64.
Ranwell, D.S.
1972.
Ecology of salt
marshes and sand dunes.
Chapman and
Hall, London. 258 pp.
Rublee, P.A., L.M.
Cammen,
and J.E.
Hobbie.
1978.
Bacteria in a North
Carolina salt marsh:
standing crop and
importance in
the decomposition of
Spartina alterniflora.
Univ. N.C. Sea
Grant Publ. 78-11.
Howarth, F.
B.J., R-W.
1980.
Lipschultz, and D. Ashendorf.
an
alternative
Salt marsh detritus:
Peterson,
interpretation of stable carbon isotope
Of
Spartina
the fate
and
ratios
Uikos
34:173-177.
alterniflora.
Schwinghamer, P., F.C.
Tan,
and D.C.
Gordon.
1983.
Stable carbon isotope
studies
on the Pecks Cove mudflat
ecosystem in the Cumberland Basin, Bay
of Fundy.
Can. J. Fish Aquat. Sci.
40:262-272.
Peterson, B.J., R.N. S;;;;;thHn;ndca;b;i
1984.
Garritt.
isotopes as tracers of organic matter
flow in salt marsh food webs. Unpubl.
MS.
Shea, M.L., R.S. Warren, and W.A. Niering.
1975.
Biochemical and transplantation
studies of the growth form of Spartina
alterniflora
Connecticut
salt
marshes.
Ecolog;56:461-466.
Pomeroy, L.R. 1959. Algal .produ;;;;;;y
in salt marshes of Georgia.
Oceanogr. 4:386-397.
58
Odum E.P., and M.E.
1973.
Fanning.
the
productivity of
Comparison of
alterniflora
and
Spartina
Spartina
cynosuroides in Georgia coastal marshes.
Bul I. Ga. Acad. Sci. 31:1-12.
Pomeroy, L.R., and R.G. Wiegert, eds.
1981.
The ecology of a salt marsh.
Springer-Verlag, New York,
271 pp.
Ponnamperuma, F.N.
1972.
of
submerged
soils.
24:29-96.
Odum, W.E., P.W. Kirk, and J.C. Zieman.
1979a.
Non-protein nitrogen compounds
associated with particles of vascular
32:363-367.
Oikos
plant
detritus.
The chemistry
Adv.
Agron.
Prinslow, T., I. Valiela, and J.M. Teal.
1974. The effect of detritus and ration
size
the
growth of
Fundulus
heterocy?tus
salt
marsh
(L.),
a
killifish. J. Exp. Mar. Biol. Ecol.
Odum, W.E., J.S. Fisher, and J.C. Pickral.
Factors controlling the flux of
1979b.
carbon
from
organic
particulate
estuarine wetlands. Pages 69-80 in R.J.
Livingston, ed. Ecological processes in
and marine systems.
Plenum
coastal
Press, New York.
16:1-10.
Prouse, N.J., D.C. Gordon, B.T. Hargrave,
C.J.
Bird,
J.
McLachlan,
J.S.S.
Lakshminarayana, J. SitaDevi, and M.L.H.
Thomas.
1983.
Primary
production:
organic matter supply to ecosystems in
the Bay of Fundy.
Bedford Institute
Oceanography
Technical
Report,
Dartmouth, N.S., Canada.
Ott, J., G. Rieger, R. Rieger, and F.
New
mouthless
Enderes.
1983.
interstitial worms from the sulfide
symbiosis with prokaryotes.
system:
Mar. Ecol. (Pubbl. Stn. Zool. Napoli 1)
3:313-333.
Redfield, A.C.
1972.
Development of the
New England salt marsh.
Ecol. Bull.
42:201-237.
Pace, M.L., S. Shimmel, and W.M. Darley.
The effect of grazing by a
1979.
gastropod, Nassarius obsoletus, on the
benthic microbial community of a salt
marsh mud flat. Estuarine Coastal Mar.
Res. 9:121-134.
Ruber, E., A. Gillis, and P.A. Montagna.
1981. Production of dominant vegetation
and of pool
algae on a northern
Massachusetts salt marsh. Bull. Torrey
Bot. Club 108:180-188.
Patrick, W.H., Jr., and R.D. DeLaune.
phosphorus
and
Nitrogen
1976.
utilization by Spartina alterniflora in
Barataria
marsh in
salt
a
Bay,
Estuarine Coastal Mar. Sci.
Louisiana.
4:59-64.
Ranwell, D.S.
1972.
Ecology of salt
marshes and sand dunes.
Chapman and
Hall, London. 258 pp.
Rublee, P.A., L.M.
Cammen,
and J.E.
Hobbie.
1978.
Bacteria in a North
Carolina salt marsh:
standing crop and
importance in
the decomposition of
Spartina alterniflora.
Univ. N.C. Sea
Grant Publ. 78-11.
Howarth, F.
Peterson, B.J., R . W .
1980.
Lipschultz, and D. Ashendorf.
Salt marsh detritus: an alternative
interpretation of stable carbon isotope
of Spartina
fate
the
and
ratios
alterniflora. Oikos 34:173-177.
Schwinghamer, P., F.C. Tan, and D.C.
1983.
Stable carbon isotope
Gordon.
on the Pecks Cove mudflat
studies
ecosystem in the Cumberland Basin, Bay
Can. J. Fish Aquat. Sci.
of Fundy.
40:262-272.
Peterson, B.J., R.W. Howarth, and R.H.
Sulfur and carbon
1984.
Garritt.
isotopes as tracers of organic matter
flow in salt marsh food webs. Unpubl.
MS.
Shea, M.L., R.S. Warren, and W.A. Niering.
Biochemical and transplantation
1975.
studies of the growth form of Spartina
salt
Connecticut
alterniflora
marshes. Ecolog;56:461-466.
Algal productivity
1959.
Pomeroy, L.R.
Limnol.
in salt marshes of Georgia.
Oceanogr. 4:386-397.
58
Siccama, T.G., and E. Porter. 1972. Lead
Bioscience
in a Connecticut salt marsh.
22:232-234.
Stiling, P.D., B.V. Brodbeck, and D.R.
nitrogen
Strong.
and
Foliar
1982.
larval parasitism as determinants of
patterns on
leafminer
distribution
Ecol. Entomol.
Spartina alterniflora.
7:447-452.
Sikora, C.W.
Sikora,
J.P.,
W.B.
Erkenbrecher, and B.C. Coull.
1977.
Significance of ATP, carbon, and caloric
content
of meiobenthic nematodes in
Mar.
partitioning
benthic
biomass.
Biol. 44:7-14.
t<, / <->,%anc_?
i
<
*tina
_l-.-.-"61:630-638.
af
Stroud,
L.M.
primary
Net
1976.
production of belowground material and
carbohydrate patterns in two height
forms of $artina alterniflora Loisel in
two
North
marshes.
Ph.D.
Carolina
Thesis.
Carolina
State
North
University, Raleigh.
!Y-isticMis
._- a n d
-.-- spk_atcl
Ecology
alterniflora.
_~-----___
Sullivan, M.L., and F.C. Daiber.
1974.
Response in production of cordgrass,
Spartina
alterniflora, to
inorganic
nitrogen
and
phosphorus
fertilizer.
Chesapeake Sci. 15:121-123.
Smith, T.J., III, and W.E. Odurn.
1981.
The effects of grazing by snow geese on
coastal
marshes.
Ecology
salt
62:98-106.
Teal, J.M. 1962.
Energy flow in the salt
marsh ecosystem of Georgia.
Ecology
43:614-624.
Smith, K.J., R.E. Good, and N.F. Good.
Production dynamics for above and
1979.
belowground components of a New Jersey
Spartina
alterniflora
tidal
marsh.
Estuarine Coastal Mar. Sci. 9:189-201.
Teal, J.M.
Nesting success of
1965.
herons and egrets in Georgia.
Wilson
Bull. 77:257-263.
A plan for the
1969.
Spinner, G.P.
marine resources of the Atlantic coastal
Published in conjunction with
zone.
The wildlife wetlands and
Folio 18:
shellfish areas of the Atlantic coastal
of the marine
atlas
Serial
zone.
Geographical
American
environment.
Society, New York.
Teal, J.M.
1984. The role of one salt
marsh in
coastal
productivity in
Productivity, pollution and policy 5
Proc. Conf. in Rio
the coastal zone.
Grande, Brazil. In press.
1983.
Oil
Teal, J.M., and R. Howarth.
a review of ecological
spill studies:
Environ.
Manage.
8:27-44.
results.
Steever, E.Z., R.S. Warren, and W.A.
Niering.
1976.
Tidal energy subsidy
and standing crop production of Spartina
alterniflora.
Estuarine Coastal Mar.
Sci. 41473-478.
1966. Gas
Teal, J-M., and J. Kanwisher.
transport in the marsh grass, Spartina
J. Exp. Bot. 17:355-361.
alterniflora.
1978.
Stewart, G-R., and D. Rhodes.
Nitrogen metabolism of halophytes. III.
New
Enzymes of ammonia assimilation.
Phytol. 80:307-3X.
The
1966.
Teal, J.M., and W. Wieser.
distribution and ecology of nematodes in
Limnol. Oceanogr.
a Georgia salt marsh.
11:217-222.
and T.O.
Lee,
Stewart, G.R., J.A.
Nitrogen metabolism of
Orebamjo. 1973.
Nitrate availability
halophytes.
II.
Phytol.
New
and
utilization.
72:539-546.
Teal, J.M., I. Valiela, and I. Berlo.
Nitrogen fixation by rhizosphere
1979.
and free-living bacteria in salt marsh
Limncl.
Oceanogr.
sediments.
241126-132.
1983.
Stiling, P.D., and D.R. Strong.
Weak competition among Spartina stem
Ecology
borers, by means of murder.
64:770-778.
and I. Valiela.
Teal, J.M., A. fG,iilin,
of
pollutants in
The
1982.
Pages 357-366 in
American salt marshes.
B. Gopal, R.E. Turner, R.G. Wetzel, a%
59
D.F. Whigham, eds.
Wetlands:
ecology
and
management.
Proc.
First
Int.
Wetlands
Conf.,
New
Delhi,
India.
September 1980.
Tippins, H.H., and R.J. Beshear.
1971.
On the habitat of Haliaspis s artinae
(Comstock)
(Homoptera:
Diaspldldae
+.
Entomol. News 82:165.
Turner, R.E. 1976.
Geographic variations
in salt marsh macrophyte production: a
review.
Contrib. Mar. Sci. Univ. Tex.
20:47-68.
Turner, R.E. 1977.
Intertidal vegetation
and commercial yields of penaeid shrimp.
Trans. Am.
Fish.
sot.
106:411-416.
Valiela, I. 1982.
Nitrogen in salt marsh
ecosystems.
Pages
649-678 in E . J .
Carpenter
and
D.G.
Capone, eds.
Nitrogen
in the marine environment.
Academic Press, New York.
1974.
and J.M.
Teal.
Valiela, I.,
salt
marsh
limitation in
Nutrient
547-563 in R.J.
Pages
vegetation.
Reimold and W.H. Queen, eds. -"Ecology
Academic Press, New
of halophytes.
York.
Valiela, I.,
Teal.
and J.M.
1978.
Inputs, outputs, and interconversions of
nitrogen in a salt marsh ecosystem.
Pages 399-414 in R.K. Jefferies
and
A.J. Davy, eds. -'-Ecological processes in
coastal
environments.
Blackwell
Scientific
Publications,
Oxford,
England.
Valiela, I., and J.M. Teal.
1979.
The
budget
of
a
salt
marsh
nitrogen
ecosystem.
Nature 280:652-656.
Valiela,
I., J.M. Teal, and W. Sass.
Nutrient retention in salt marsh
1973.
fertilized with
experimentally
plots
Estuarine Coastal Mar.
sewage sludge.
Sci. 1:261-269.
Valiela, I., J.M. Teal, and W.J. Sass.
Production and dynamics of salt
1975.
marsh vegetation and effect of sewage
Biomass, production and
contamination.
Appl. Ecol.
species composition. J.
12:973-982.
Valiela, I., J.M. Teal, and N.Y. Persson.
1976.
Production
and
dynamics of
experimentally
enriched
salt
marsh
vegetation:
belowground
biomass.
Limnol. Oceanogr. 21:245-252.
Valiela, I., J.M. Teal, and W.G. Deuser.
1978a.
The nature of growth forms in
the
salt
marsh
grass
Spartina
alterniflora.
Am.
112:461-470.
Nat.
Valiela, I., J.M. Teal, S. Volkmann, D.
Shafer,
and E.J.
1978b.
Carpenter.
Nutrient and particulate fluxes in a
salt marsh ecosystem: tidal exchanges
and
inputs by
precipitation
and
groundwater.
Limnol.
Oceanogr.
23:798-812.
Valiela, I., E. Howes, R. Howarth, A.
Giblin, K. Foreman, J.M. Teal, and J.E.
Hobbie.
1982.
The
regulation
of
primary production and decomposition in
a salt marsh ecosystem.
Pages 151-168
in B. Gopal, R.E. Turner, R.G. Wetzel,
%d
D.F.
Whigham,
eds.
Wetlands:
ecology and management.
Proc.
First
Int. Wetland Conf., New Delhi, India.
September 1980.
Valiela, I., J.M. Teal, S. Volkmann, R.A.
Allen.
Van
Etten,
and S.
1984.
Decomposition in salt marsh ecosystems:
the phases and major factors affecting
disappearance of aboveground organic
Mar.
Biol.
Exp.
Ecol.
matter.
J.
89:29-54.
Valiela, I., J.M. Teal, C. Cogswell, S.
Allen, D. Geohringer, R. Van Etten, J.
Some
long-term
Hartman.
1985.
consequences of sewage contamination in
Pages 301-316 in
salt marsh ecosystems.
Kaynor,
r
Godfrey, E . R .
P.J.
eds.
Benforado,
and J.
Pelczarski,
considerations in wetland
Ecological
Van
treatment of municipal wastewater.
Nostrand Reinhold, New York.
Van Raalte, C.D., I. Valiela, and J.M.
Production of epibenthic
1976.
Teal.
light and nutrient
salt marsh algae:
Oceanogr. 21:
Limnol.
limitation.
862-872.
Vince, S.W. 1979.
salt marsh
to
Response of herbivores
Ph.D.
fertilization.
tn.
Of
Thesis.
Boston
Mass. 85 pp.
University,
Boston,
sh
S.
r.
in
na
j-:
Vince, S., I. Valiela, N. Backus, and J.M.
Teal.
1976.
Predation by the salt
marsh killifish Fundulus heteroclitus
(L.) in relation to prey size and
habitat structure:
consequence for prey
distribution and abundance. J. Exp.
Mar. Biol. Ecol. 23:255-266.
Vince, S.W., I. Valiela, and J.M. Teal.
1981.
An experimental study of the
structure
of
herbivorous
insect
Ecology
communities in a salt marsh.
62:1661-1678.
The role of grass
1975.
Welsh, B.L.
shrimp, Palaemonetes pugio, in a tidal
Ecology 56:513-533.
marsh ecosystem.
Werme, C.E.
1981.
Resource partitioning
Ph.D.
in a salt marsh fish community.
126
Thesis.
Boston University, Mass.
PP.
Wcl.zf'l, K.L. 1975. An experimental study
0 I tie t.r i td 1
in a
carbon utilizatian
i;cor*yia
salt.
Ph.D.
Thesis.
marsh.
130 pp.
University of !;eor<lia, Athens.
Wetzel, R.L. 1976. Carbon resources of a
invertebrate,
salt
benthic
marsh
Say (Mollusca:
obsoletus
Nassarius
293-308 in M.
Pages
Nassariidae):
processes.
Estuarine
Wiley,
ed.
Academic Press, New York.
Wiegert, R.G., A.G. Chalmers, and P.F.
Randerson.
1983.
Productivity
gradients in salt marshes: the response
of
Spartina
alterniflora
to
experimentally manipulated soil water
movement. Oikos 41:1-6.
Whitlatch, R.B.
1982. The ecology of New
tidal
England
flats:
community
profile.
U.S. Fish Wildl. terv., Biol.
Serv.
Program,
Washington,
D.C.
FWS'OBS-81/01. 125 pp.
Whitney, D.E., and W.M. Darley.
1981. No
title.
Quoted in Pomeroy and Weigert
1981.
Wiltse, W.I., K.H. Foreman, J.M. Teal, and
I. Valiela. 1984.
Effects of predators
and food resources on the macrobenthos
J. Mar. Res.
of salt marsh creeks.
42(4):923-942.
Dunstan,
and W.S.
Windom, H.L., W.M.
River input of organic
Gardner. 1975.
the
and
nitrogen to
phosphorus
southeastern salt marsh and estuarine
Pages
30931.3 ,g F.G.
environment.
Howell, J.B. Gentry, and M.H. Smith,
Mineral cycling in southeastern
eds.
held
at
Proc.
Symp.
ecosystems.
Augusta, Ga. 1974.
Woodhouse, W.W., Jr., E.D. Seneca, and
Marsh building with
S.W. Broome. 1972.
dredge spoil in North Carolina. N.C.
Agric. Exp. Stn. Bull. 445.
28 PP-
61
1272 -101
?EPORT OOWMENTATlON
PAGE
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Report 85(7.4) :”
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5. Re port oa t .
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1 June 19R6
'The Ecology of Regularly Flooded Salt Marshes of New England: A
/I.-Community Profile
-----~____-______
_~I__-..8. FJarformrng Org'"'l~"on Rep,.
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‘John
M.
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Fish and Wildlife Service
Division of Biological Services
National Coastal Ecosystems Team
U.S. Department of the Interior
Washington, DC 20240
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The report summarizes and synthesizes infotmation on the ecology of intertidal, regulat
flooded Spartina- alterniflora
marshes in New England. The report focuses on the Great
Sippewissett Salt Marsh in Falmouth, Massachusetts, where the author and other scientist:
have investigated the basic structure and functions of these wetlands. Marsh plant productivity and decomposition and the related processes of bacterially mediated cycling of
nitrogen, phosphorus, sulfur, and carbon through the marsh are discussed in this profile,
These marshes are dominated both vegetationally and ecologically by a single emergent
plant species, Spartina
alterniflora. Dead decomposed Spartina, associated bacteria, ber
- _._”
thic algae, and fungi--on~~~rsC;"surface support large populations of a few dominant
species of macroinvertebrates, such as bivalve mollusks and fiddler crabs, and small fist
such as mummichogs and striped killifish.
Salt marshes have value as possible exporters and transformers of biogenic materials.
Studies at the Great Sippewissett Marsh have considered the role of marshes as processor
of human-derived materials such as petroleum products, heavy metals, and nutrients in
sewage sEudge.
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Primary bloioglcar productivity
Coastal wetlands
Ecology
Decoeposition
b.
Idmtlf,sn/Cvcn Ended Terms
hes
Human impacts
C
Spartina
a r alterniflora
b o n
New England
Nutrient cycling
f l u x
Sal t mars
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