- Canadian Museum of Nature
P.O. Box 3443, Station D
Ottawa, ON K1P 6P4
CANADA - 613-364-4066
Jean-Marc Gagnon
Canadian Museum of Nature, Research & Collections, Department Member
- Marine Ecology, Collections Management, Benthic Ecology, Aquatic Invertebrates, Marine benthos ecology, Marine Benthic Macrofauna, and 23 moreThalassinideans, Callianassidae Burrows, Scavenging Amphipods, Natural History Museums, Giant File Clams, Acesta excavata, Invertebrate Collections, Marine bioturbation, Centre for Research Collections (CRC), Taxonomy, Functional Ecology, Marine invertebrates, Natural history collections, Polychaetes, Bioturbation, Macrofauna, S. droebachiensis, Northwest Atlantic, Grand Bank of Newfoundland, Collection Development Strategy, Fjord, S. pallidus, and St. Lawrence Estuaryedit
- SPECIALTIES •Zoology. •Marine ecology and biology. •Taxonomy and ecology of marine benthic invertebrates (pa... moreSPECIALTIES
•Zoology.
•Marine ecology and biology.
•Taxonomy and ecology of marine benthic invertebrates (particularly polychaetes, molluscs, crustacean isopods and amphipods, echinoderms).
•Environmental impact studies – Multivariate Analyses.
•Natural history collections management.
PROJECTS
Taxonomy
•Description of a new species of Giant File Clam (Mollusca; Bivalvia, Limidae; Acesta nov. sp.) from the northwestern Atlantic.
•Description of a new species of marine worm (Annelida; Polychaeta; Chaetopteridae; Chaetopterus nov. sp.) from the St. Lawrence estuary.
•Morphological and genetic variations among populations of the Lady Crab (Crustacea; Decapoda; Portunidae; Ovalipes ocellatus) along the east coast of North America.
Ecology
•Mesocosm observations of the burrowing shrimp Calocaris templemani (Decapoda: Thalassinidea) and its bioturbation activities in soft sediments of the Laurentian Trough.
•Temporal variations in the structure of deepwater benthic invertebrate community from the St. Lawrence Estuary maintained in mesocosm experiments.
•Ecology of scavenging amphipods (Crustacea: Peracarida; Gammaridea; Anonyx spp.) from deepwater benthic communities in the St. Lawrence Estuary.
•Bioturbation by invertebrates from deepwater benthic communities in the St. Lawrence Estuary, and its impact on chemical burial.
Functional Morphology
•Spine morphology associated with burrowing behaviour in the heart urchin Brisaster fragilis (Echinodermata; Echinoidea; Spatangoida).
•The functional relationship between burrowing (ghost) shrimps morphology (Thalassinidea; Callianassidae) and their burrow architecture.
Collections
• President of the Society for the Preservation of Natural History Collections (www.spnhc.org)
•Organizating and hosting the 25th annual meeting of the Society for the Preservation of Natural History Collections (SPNHC), Ottawa 2010.
•Canadian Museum of Nature Bryozoa slide collection project: When Byne’s Disease Attacks Bryozoans.
Professional Services
•Taxonomic identification of marine benthic invertebrates – Canadian East and Arctic coasts.
•Environmental impact studies – marine benthos.
•Producer of plastic PET containers for museum objects.
EDUCATION
•Postdoctoral Research, Institut national de la recherche scientifique (INRS-Océanologie), Rimouski, 1993-94.
Subject: Environmental impacts of dredged sediments from seaports on benthic communities at offshore dumping sites. Supervisor: Dr. Georges Drapeau
•Postdoctoral Research, Université du Québec à Rimouski / Institut Maurice-Lamontagne,1991-93.
Subject: Study of marine benthic invertebrates and sediment bioturbation in mesocosms., Supervisor: Dr. Norman Silverberg.
•Ph.D., Marine Ecology, Memorial University of Newfoundland, Department of Biology, 1991.
Thesis title: The significance of body size and foraging mode in the structuring of Marine soft bottom polychaete assemblages, Supervisor: Dr. Richard L. Haedrich.
•M.Sc., Marine Ecology, Université de Montréal, Département de Sciences Biologiques, 1983.
Thesis title: Cycle de développement, écologie et succès d'Anonyx makarovi, amphipode gammaridien nécrophage saisonnier dans le circa-littoral de deux écosystemes du Golfe du Saint Laurent, Supervisor: Dr. Pierre Brunel.
•B.Sc., Biological Sciences (Zoology concentration). Université de Montréal, Département de Sciences Biologiques, 1980.
Honours title: Cycle de développement de Munnopsis typica (Crustacea, Isopoda) dans la nappe profonde de l'estuaire maritime du St-Laurent, Supervisor: Dr. Pierre Brunel.edit
the Canadian Museum of Nature (formerly known as the National Museum of Natural Sciences, Canada) in Ottawa, retiring in September 1997 after '30 years 1 month'. Her early work involved the sorting and identifying marine invertebrates for... more
the Canadian Museum of Nature (formerly known as the National Museum of Natural Sciences, Canada) in Ottawa, retiring in September 1997 after '30 years 1 month'. Her early work involved the sorting and identifying marine invertebrates for the Canadian Oceanographic Identification Centre (NMNS/COIC; then called the Canadian Aquatic Identification Centre, CAIC). Through this experience, Judy became very familiar with essentially all marine invertebrates, which quickly led to her major interest in polychaetes. Then, in 1979, she was formally appointed as Invertebrate Zoologist (and then, Assistant Curator and Assistant Collection Manager) in charge of the non-crustacean collections, which included the National Annelid Collection. Judy's first two publications were on tunicates and barnacles, but her first polychaete paper soon appeared (Fournier & Levings, 1982), and was quickly followed by eight peer-reviewed taxonomic articles over the next 12 years. Considering that her work was primarily about caring for collections and not so much about research, this was a fine accomplishment. Of those, we can highlight the description of new species, the arenicolid Branchiomaldane labradorensis (Fournier & Barrie, 1987), scalibregmatid Axiokebuita millsi (Pocklington & Fournier, 1987), hesionid Microphthalmus coustalini and M. hystrix (Fournier, 1991), and dorvilleid Ophryotrocha spatula (Fournier & Conlan, 1994), as well as the redescription of Cossura longocirrata (Fournier & Petersen, 1991). While Judy's career as a polychaete expert was relatively short, mainly due to her other curatorial responsibilities and the major move of the museum collections in 1996-97, she did leave more than publications. She was happy to collaborate with novices in polychaete taxonomy, helping them produce several papers. As a very good illustrator, she liked to provide her own illustrations to these papers. For the Canadian authors of this obituary, representing the few remaining polychaete specialists in Canada, Judy was the Annelid person at the Museum when we first got involved in polychaete identification. Judy had an encyclopaedic
Research Interests: Obituary and Polychaeta
Grass shrimp collected by the Community Aquatic Monitoring Program (CAMP) in estuaries of the southern Gulf of St. Lawrence, Canada were previously assumed to be the native Palaemon vulgaris Say, 1818. Taxonomic identification of grass... more
Grass shrimp collected by the Community Aquatic Monitoring Program (CAMP) in estuaries of the southern Gulf of St. Lawrence, Canada were previously assumed to be the native Palaemon vulgaris Say, 1818. Taxonomic identification of grass shrimps from CAMP estuaries revealed most individuals were P. vulgaris, but several from the Souris River and Trout River estuaries in Prince Edward Island (PEI) belong to the European species P. adspersus Rathke, 1837. We provide the first documented presence of P. adspersus in PEI estuaries, extending its known range in Atlantic Canada from coastal Newfoundland and the Magdalen Islands. Boat traffic was probably responsible for the introduction of P. adspersus. The results highlight the importance of community-based monitoring in coastal ecology.
Research Interests:
Chaetopterus is a globally distributed genus of marine Annelida with a long history of taxonomic confusion. Here, we describe Chaetopterus bruneli sp. nov. from a depth of 350 m in the St. Lawrence Estuary, eastern Canada. The new species... more
Chaetopterus is a globally distributed genus of marine Annelida with a long history of taxonomic confusion. Here, we describe Chaetopterus bruneli sp. nov. from a depth of 350 m in the St. Lawrence Estuary, eastern Canada. The new species represents the northernmost record for Chaetopterus in the western Atlantic to date. The similar European species Chaetopterus norvegicus M. Sars, 1835 is resurrected from long-standing synonymy and redescribed from type material, and a lectotype is designated.
Research Interests:
Dynoides canadensis sp. nov. is described from the southwestern coast of British Columbia, Canada. This species differs from its closely related species, D. elegans (Boone, 1923)), by the presence of a smooth pleotelson without prominent... more
Dynoides canadensis sp. nov. is described from the southwestern coast of British Columbia, Canada. This species differs from its closely related species, D. elegans (Boone, 1923)), by the presence of a smooth pleotelson without prominent rounded tubercle on the basal part of the pleotelsonic sinus, its sinus wall lacking crenulation; in having the penial processes length 7.7 × basal width and acute distal apex instead of 2.3 × basal width and rounded and blunt distal apex in D. elegans. This new species also has an appendix masculina with the distal apex extending somewhat beyond its base, instead of not reaching the base as is the case for D. elegans. A map of the distribution for the northeastern Pacific species of Dynoides Barnard, 1914 (D. elegans (Boone, 1921); D. crenulatus and D. saldanai Carvacho & Haasmann, 1984; and D. dentisinus Shen 1929) in the northeastern Pacific is provided. The new species is abundant in the western coastal zone of British Columbia. A revised generic diagnosis is provided for the genus Dynoides.
Research Interests:
We analyze the morphological and genetic variability within and between seven species of Acesta and specimens recently collected in the northwest Atlantic using traditional morphological measurements, landmark-based geometric... more
We analyze the morphological and genetic variability within and between seven species of Acesta and specimens recently collected in the northwest Atlantic using traditional morphological measurements, landmark-based geometric morphometrics, and the cytochrome oxidase subunit I (COI) gene sequences, with particular emphasis on North Atlantic species. Shell morphology and external shell appearance do not allow reliable distinction between the widely recognized northeastern Atlantic A. excavata and other northwest Atlantic species or populations of Acesta, with the exception of A. oophaga. Similarly, shape analysis reveals a wide variability within northeastern Atlantic A. excavata, and significant morphological overlap with A. bullisi from the Gulf of Mexico and A. rathbuni from the southwestern Pacific and South China Sea. Specimens from the northwestern and Mid-Atlantic display shell shapes marginally similar to that of A. excavata. These differences are at least partly related to anterior or posterior shifting of the shell body and to the opposite shifting of the hinge line/dorsal region and upper lunule. These morphological variations, along with the midline-width-ratio, explain much of the variability extracted by principal component analysis. Results from a mitochondrial DNA barcode approach (COI), however, suggest that the northwest Atlantic specimens belong to a new species for which we propose the name Acesta cryptadelphe sp. nov. Differences in larval shell sizes between northeastern and northwestern Atlantic specimens are consistent with this result.
Research Interests:
Live, Iceland scallops, Chlamys islantdica , were enumerated and their occurrences assigned to substratum coarseness grades along five photographic transects (8-10 km in length) covering areas of the northeastern Grand Bank of... more
Live, Iceland scallops, Chlamys islantdica , were enumerated and their occurrences assigned to substratum coarseness grades along five photographic transects (8-10 km in length) covering areas of the northeastern Grand Bank of Newfoundland. Scallops were disproportionately (53-94%) associated with the coarsest grade of substratum comprising dense gravel-cobble (80-100% by area). Overall, scallops were uncommon to rare on predominanrly sand substrata. Average densities of scallops per photograph (5,4 m2) ranged from 0.5 to 13.8 in cobble fields and from 0.02 to 1.7 on open sand.It is hypothesized that Iceland scallops on the northeastern Grand Bank are aggregated on coarse substrata because of a strong propensity towards byssal attachment at all pos-larval life history stages. A survey of substratum associations of extant species of Chlamys reveals that, with few exceptions, association with coarse substrata is common within the genus
Research Interests:
Research Interests:
Previous inshore and offshore faunal surveys along the east coast of Newfoundland and Labrador, Canada, had indicated that the only strongylocentrotid sea urchin species in this region was Strongylocentrotus droebachiensis. Examination of... more
Previous inshore and offshore faunal surveys along the east coast of Newfoundland and Labrador, Canada, had indicated that the only strongylocentrotid sea urchin species in this region was Strongylocentrotus droebachiensis. Examination of sea urchins collected ...
Research Interests:
Research Interests:
Research Interests:
We analyze the morphological and genetic variability within and between seven species of Acesta and specimens recently collected in the northwest Atlantic using traditional morphological measurements, landmark-based geometric morpho-... more
We analyze the morphological and genetic variability within and between seven species of Acesta and specimens recently collected in the northwest Atlantic using traditional morphological measurements, landmark-based geometric morpho- metrics, and the cytochrome oxidase subunit I (COI) gene sequences, with particular emphasis on North Atlantic species. Shell morphology and external shell appearance do not allow reliable distinction between the widely recognized north- eastern Atlantic A. excavata and other northwest Atlantic species or populations of Acesta, with the exception of A. oopha- ga. Similarly, shape analysis reveals a wide variability within northeastern Atlantic A. excavata, and significant morphological overlap with A. bullisi from the Gulf of Mexico and A. rathbuni from the southwestern Pacific and South China Sea. Specimens from the northwestern and Mid-Atlantic display shell shapes marginally similar to that of A. exca- vata. These differences are at least partly related to anterior or posterior shifting of the shell body and to the opposite shift- ing of the hinge line/dorsal region and upper lunule. These morphological variations, along with the midline-width-ratio, explain much of the variability extracted by principal component analysis. Results from a mitochondrial DNA barcode approach (COI), however, suggest that the northwest Atlantic specimens belong to a new species for which we propose the name Acesta cryptadelphe sp. nov. Differences in larval shell sizes between northeastern and northwestern Atlantic specimens are consistent with this result.
Key words: Newfoundland, Nova Scotia, deep-water canyons, geometric morphometrics, shape analysis, COI
Résumé
Nous analysons la variabilité morphologique et génétique intra- et interspécifique de sept espèces d’Acesta et de spécimens récemment collectés dans le nord-ouest de l'Atlantique en utilisant des mesures morphologiques traditionnelles, la morphométrie géométrique et la séquence de la sous-unité 1 du gène de la cytochrome c oxydase (gène COI), avec un accent particulier sur les espèces de l'Atlantique Nord. La morphologie de la coquille et son apparence externe ne permettent pas une distinction fiable entre l'espèce bien connue de l’Atlantique nord-est, A. excavata, et d'autres espèces ou populations d’Acesta de l'Atlantique nord-ouest, à l'exception d’A. oophaga. De même, l'analyse de la forme révèle une grande variabilité au sein d’A. excavata et un chevauchement morphologique significative avec A. bullisi du Golfe du Mexique et A. rathbuni du Pacifique sud-ouest et du sud de la Mer de Chine. La forme de la coquille des spécimens de l’Atlantique nord-ouest et nord-central est marginalement similaire à celle d’A. excavata. Ces différences sont au moins en partie liées au déplacement antérieur ou postérieur du corps de la coquille et le déplacement opposé de la région dorsale, de la charnière et de la partie supérieure de la lunule. Ces variations morphologiques, ainsi que le ratio de la ligne médiane, expliquent une grande partie de la variabilité extraite par l’analyse en composantes principales. Les résultats de l’approche de code-barres génétique avec l'ADN mitochondrial (COI), cependant, suggèrent que les spécimens de l'Atlantique
Key words: Newfoundland, Nova Scotia, deep-water canyons, geometric morphometrics, shape analysis, COI
Résumé
Nous analysons la variabilité morphologique et génétique intra- et interspécifique de sept espèces d’Acesta et de spécimens récemment collectés dans le nord-ouest de l'Atlantique en utilisant des mesures morphologiques traditionnelles, la morphométrie géométrique et la séquence de la sous-unité 1 du gène de la cytochrome c oxydase (gène COI), avec un accent particulier sur les espèces de l'Atlantique Nord. La morphologie de la coquille et son apparence externe ne permettent pas une distinction fiable entre l'espèce bien connue de l’Atlantique nord-est, A. excavata, et d'autres espèces ou populations d’Acesta de l'Atlantique nord-ouest, à l'exception d’A. oophaga. De même, l'analyse de la forme révèle une grande variabilité au sein d’A. excavata et un chevauchement morphologique significative avec A. bullisi du Golfe du Mexique et A. rathbuni du Pacifique sud-ouest et du sud de la Mer de Chine. La forme de la coquille des spécimens de l’Atlantique nord-ouest et nord-central est marginalement similaire à celle d’A. excavata. Ces différences sont au moins en partie liées au déplacement antérieur ou postérieur du corps de la coquille et le déplacement opposé de la région dorsale, de la charnière et de la partie supérieure de la lunule. Ces variations morphologiques, ainsi que le ratio de la ligne médiane, expliquent une grande partie de la variabilité extraite par l’analyse en composantes principales. Les résultats de l’approche de code-barres génétique avec l'ADN mitochondrial (COI), cependant, suggèrent que les spécimens de l'Atlantique
Research Interests:
Résumé La liste des noms français, anglais et latins des 55 espèces de mulettes du Canada (Ordre: Unionoida, Familles: Margaritiféridés et Unionidés) trouvées jusqu'à présent a été mise à jour. Ce travail fait suite à... more
Résumé La liste des noms français, anglais et latins des 55 espèces de mulettes du Canada (Ordre: Unionoida, Familles: Margaritiféridés et Unionidés) trouvées jusqu'à présent a été mise à jour. Ce travail fait suite à l'ouvrage classique d'Arthur H. Clarke
Research Interests:
Research Interests:
The life history and fecundity of five shallow-water lysianassoids from the Saint Lawrence Estuary were examined. Orchomenella minuta and Or. pinguis are annual and iteroparous (two broods), Psammonyx terranovae is iteroparous (two... more
The life history and fecundity of five shallow-water lysianassoids from the Saint Lawrence Estuary were examined. Orchomenella minuta and Or. pinguis are annual and iteroparous (two broods), Psammonyx terranovae is iteroparous (two broods) and probably biennial, ...
Research Interests:
The heart urchin Brisaster fragilis is an important bioturbator found in the Estuary and Gulf of St. Lawrence. Several adaptations allow it to move within fine sediments (e.g., test shape, spine morphology, and distribution), which are... more
The heart urchin Brisaster fragilis is an important bioturbator found in the Estuary and Gulf of St. Lawrence. Several adaptations allow it to move within fine sediments (e.g., test shape, spine morphology, and distribution), which are compared here to those of its Pacific sibling species B. latifrons. While ventral spatulate spines and dorsal and anterolateral curvilinear spines are similar between the two species, anterior spines differ significantly: sigmoid-shaped for B. fragilis and curvilinear for B. latifrons. This morphological difference, in addition to a narrower plastron for B. fragilis, suggests a different digging strategy. In situ video observations of B. fragilis show a “dig and move” strategy: anterior spines “dig” forward at the sediment while the plastron spines “move” the urchin into the newly created space. B. latifrons on the other hand uses an oblique rocking motion. This suggests that generalizations derived from one or few species displaying similar body shapes may not be possible. Factors such as sediment depth (i.e., the amount of sediment above the urchin) are likely to affect movement and force the animal to employ a different digging strategy, even within a single species. The role of spines for locomotion is further discussed, with additional reference to tubercle morphology.
Research Interests:
"In vivo observations in laboratory mesocosms and aquaria, accompanied with in situ photographic surveys, have shown that the burrowing shrimp Calocaris templemani has a significant impact on bottom sediment dynamics and geochemistry in... more
"In vivo observations in laboratory mesocosms and aquaria, accompanied with in situ photographic surveys, have shown that the burrowing shrimp Calocaris templemani has a significant impact on bottom sediment dynamics and geochemistry in the St. Lawrence Estuary. This burrowing shrimp establishes and maintains complex semi-permanent burrows made up of several interconnected, ‘U-shaped’ galleries with generally four or more openings to the sediment surface. In the Estuary, at 345 m depth, Calocaris average density was estimated at 3.4 individuals m−2. Observed individual burrows reached a maximum volume of 0.54 L. C. templemani displaces this volume of mostly anoxic sediments from the subsurface layers (down to 15 cm) to the sediment surface, thereby obscuring some of the natural stratification patterns. With an estimated turnover rate of about 8 L m−2 year−1 of sediment, our calculations suggest that over a period of about 18.75 years, all the sediment to a depth of 15 cm will have been reworked by C. templemani alone.
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Research Interests:
Live, Iceland scallops, Chlamys islantdica , were enumerated and their occurrences assigned to substratum coarseness grades along five photographic transects (8-10 km in length) covering areas of the northeastern Grand Bank of... more
Live, Iceland scallops, Chlamys islantdica , were enumerated and their occurrences assigned to substratum coarseness grades along five photographic transects (8-10 km in length) covering areas of the northeastern Grand Bank of Newfoundland. Scallops were disproportionately (53-94%) associated with the coarsest grade of substratum comprising dense gravel-cobble (80-100% by area). Overall, scallops were uncommon to rare on predominanrly sand substrata. Average densities of scallops per photograph (5,4 m2) ranged from 0.5 to 13.8 in cobble fields and from 0.02 to 1.7 on open sand.It is hypothesized that Iceland scallops on the northeastern Grand Bank are aggregated on coarse substrata because of a strong propensity towards byssal attachment at all pos-larval life history stages. A survey of substratum associations of extant species of Chlamys reveals that, with few exceptions, association with coarse substrata is common within the genus.
Research Interests:
Closed-circulation, water jacket-insulated laboratory basins (benthic mesocosms) of 1 m2 surface area preserved the abu ndance and species composition of the principal benthic macrofauna of the 350-m-deep Laurentian Trough for periods... more
Closed-circulation, water jacket-insulated laboratory basins (benthic mesocosms) of 1 m2 surface area preserved the abu ndance and species composition of the principal benthic macrofauna of the
350-m-deep Laurentian Trough for periods exceeding a year, Abundance of meiofauna, and bacterial numbers and activity were also sustained. Although the overlying water was permitted to equilibrate with the atmosphere, oxygen penetration depths in the sediment stabilized at about twice the thickness of the in situ aerobic layer, while whole-sediment respiration rates remained within the range observed for freshly obtained sediment cores. Build-up of metabolic by-products in the overlying water was controlled by bi-monthly replacement of a third of the bottom water. The study demonstrated that close observation of organism behaviour and biogeochemical processes within deep coastal sediments can be carried out in laboratory mesocosms.
350-m-deep Laurentian Trough for periods exceeding a year, Abundance of meiofauna, and bacterial numbers and activity were also sustained. Although the overlying water was permitted to equilibrate with the atmosphere, oxygen penetration depths in the sediment stabilized at about twice the thickness of the in situ aerobic layer, while whole-sediment respiration rates remained within the range observed for freshly obtained sediment cores. Build-up of metabolic by-products in the overlying water was controlled by bi-monthly replacement of a third of the bottom water. The study demonstrated that close observation of organism behaviour and biogeochemical processes within deep coastal sediments can be carried out in laboratory mesocosms.
Research Interests:
The sensitivity of oceanic thermohaline circulation to freshwater perturbations is a critical issue for understanding abrupt climate change. Abrupt climate fluctuations that occurred during both Holocene and Late Pleistocene times have... more
The sensitivity of oceanic thermohaline circulation to freshwater
perturbations is a critical issue for understanding abrupt climate
change. Abrupt climate fluctuations that occurred during both
Holocene and Late Pleistocene times have been linked to changes
in ocean circulation, but their causes remain uncertain. One of
the largest such events in the Holocene occurred between 8,400
and 8,000 calendar years ag0 (7,650- 7,200 14C years ago), when
the temperature dropped by 4-8 °C in central Greenland1 and
1.5-3 °C at marine and terrestria sites around the northeastern North Atlantic Ocean. The pattern of cooling implies that heat transfer from the ocean to the atmosphere was reduced in the North Atlantic. Here we argue that this cooling event was forced by a massive outflow of fresh water from the Hudson Strait. This
conclusion is based on our estimates of the marine 14C reservoir
for Hudson Bay which, in combination with other regional data,
indicate that the glacial lakes Agassiz and Ojibwaf-Il (originally
dammed by a remnant of the Laurentide ice sheet) drained
catastrophically - 8,470 calendar years ago; this would have
released > 1014 m3 of fresh water into the Labrador Sea. This
finding supports the hypothesis that a sudden increase in
freshwater flux from the waning Laurentide ice sheet reduced
sea surface salinity and altered ocean circulation, thereby initiating
the most abrupt and widespread cold event to have occurred in
the past 10,000 years.
perturbations is a critical issue for understanding abrupt climate
change. Abrupt climate fluctuations that occurred during both
Holocene and Late Pleistocene times have been linked to changes
in ocean circulation, but their causes remain uncertain. One of
the largest such events in the Holocene occurred between 8,400
and 8,000 calendar years ag0 (7,650- 7,200 14C years ago), when
the temperature dropped by 4-8 °C in central Greenland1 and
1.5-3 °C at marine and terrestria sites around the northeastern North Atlantic Ocean. The pattern of cooling implies that heat transfer from the ocean to the atmosphere was reduced in the North Atlantic. Here we argue that this cooling event was forced by a massive outflow of fresh water from the Hudson Strait. This
conclusion is based on our estimates of the marine 14C reservoir
for Hudson Bay which, in combination with other regional data,
indicate that the glacial lakes Agassiz and Ojibwaf-Il (originally
dammed by a remnant of the Laurentide ice sheet) drained
catastrophically - 8,470 calendar years ago; this would have
released > 1014 m3 of fresh water into the Labrador Sea. This
finding supports the hypothesis that a sudden increase in
freshwater flux from the waning Laurentide ice sheet reduced
sea surface salinity and altered ocean circulation, thereby initiating
the most abrupt and widespread cold event to have occurred in
the past 10,000 years.
Research Interests:
Previous inshore and offshore faunal surveys along the east coast of Newfoundland and Labrador, Canada, had indicated that the only strongylocentrotid sea urchin species in this region was Strongylocentrotus droebachiensis. Examination of... more
Previous inshore and offshore faunal surveys along the east coast of Newfoundland and Labrador, Canada, had indicated that the only strongylocentrotid sea urchin species in this region was Strongylocentrotus droebachiensis. Examination of sea urchins collected at depths ranging from 10 to 387 m revealed that, with a few exceptions classified as 'unknown', all specimens from 60 m and deeper are S. pallidus. The two species of sea urchins are distinguished on the basis of the shape of tridentate and globiferous pedicellariae, the colour of oral spines, the number of wedges on aboral primary spines and the number of ambulacral pore-pairs. Intraspecific variations among these characters can be substantial, particularly in S. droebachiensis. In the few instances where significant trends were found along the latitudinal and bathymetric gradients, these could be explained by the variation in specimens' body size alone. Nevertheless, univariate comparisons of these
characters and their relationships (or lack thereof) with station latitude, water depth and body size support the widely held view that S. pallidus is not a colour variant of S. droebachiensis
but a separate species. Multivariate analyses based on the five characters also support the recognition of two distinct species of Strongylocentrotus in the Northwest Atlantic. A revised identification key is proposed to better distinguish these two species.
characters and their relationships (or lack thereof) with station latitude, water depth and body size support the widely held view that S. pallidus is not a colour variant of S. droebachiensis
but a separate species. Multivariate analyses based on the five characters also support the recognition of two distinct species of Strongylocentrotus in the Northwest Atlantic. A revised identification key is proposed to better distinguish these two species.
Research Interests:
Organochlorine contaminants (OCs) and stable isotopes of carbon (δ13C) and nitrogen (δ15N) were determined in 7 benthic and 7 pelagic marine invertebrate species from the North American Arctic to identify factors influencing OC... more
Organochlorine contaminants (OCs) and stable isotopes of carbon (δ13C) and nitrogen (δ15N) were determined in 7 benthic and 7 pelagic marine invertebrate species from the North American
Arctic to identify factors influencing OC concentrations. Values of δ13C separated benthic (enriched in 13C) from pelagic species and δ15N values gave a logical approximation of trophic level
(TL). With few exceptions, OC concentrations in invertebrates were low (most were <5 ng g–1 wet wt) relative to the same or similar species in temperate waters and in the range expected for lower TL
Arctic organisms. Polychlorinated biphenyls (PCBs) were the predominant OC group and lower chlorinated PCB congeners and hexachlorocyclohexane (HCH) isomers were the most common individual OCs in most species. Relatively higher levels of PCBs and high proportions of highly chlorinated PCB congeners were found in a small number of the pelecypod samples (Mytilus edulis and Mya
truncata), suggesting that local harbors and communities can be point sources of PCBs in the Arctic. The OC concentrations (wet wt) varied by up to 2 orders of magnitude among species and were more variable among the benthic invertebrates. Lipid content, δ13C and δ15N were significant variables related to OC concentration, but differences among species remained after accounting for these
variables. Scavenging, high TL, high lipid content and local point sources can all contribute to higher OC concentrations in Arctic marine invertebrates.
Arctic to identify factors influencing OC concentrations. Values of δ13C separated benthic (enriched in 13C) from pelagic species and δ15N values gave a logical approximation of trophic level
(TL). With few exceptions, OC concentrations in invertebrates were low (most were <5 ng g–1 wet wt) relative to the same or similar species in temperate waters and in the range expected for lower TL
Arctic organisms. Polychlorinated biphenyls (PCBs) were the predominant OC group and lower chlorinated PCB congeners and hexachlorocyclohexane (HCH) isomers were the most common individual OCs in most species. Relatively higher levels of PCBs and high proportions of highly chlorinated PCB congeners were found in a small number of the pelecypod samples (Mytilus edulis and Mya
truncata), suggesting that local harbors and communities can be point sources of PCBs in the Arctic. The OC concentrations (wet wt) varied by up to 2 orders of magnitude among species and were more variable among the benthic invertebrates. Lipid content, δ13C and δ15N were significant variables related to OC concentration, but differences among species remained after accounting for these
variables. Scavenging, high TL, high lipid content and local point sources can all contribute to higher OC concentrations in Arctic marine invertebrates.
Research Interests:
Two large bivalve specimens collected in Bay d'Espoir, a deep fjord situated on the south coast of Newfoundland, are described and identified as belonging to the species Acesta excavata (Fabricius 1779). In situ observations onboard the... more
Two large bivalve specimens collected in Bay d'Espoir, a deep fjord situated on the south coast of Newfoundland, are described and identified as belonging to the species Acesta excavata (Fabricius 1779). In situ observations onboard the manned submersible PISCES IV and color videos have provided information on the vertical distribution, density and habitat of the species. Maximum abundances of about 15 large individuals/m2 occurred on sheltered rock outcrops at depth ranging from 550 to 775 m, where warm (6°C) continental slope water is found. Differences in shape and thickness between the valves of the two specimens appear to be related to the degree of exposure to rock falls (i.e., sheltered versus exposed habitat). Prior to this account, the European Giant File Clam had never been encountered west of the Azores Islands in the
North Atlantic.
North Atlantic.
Research Interests:
Research dives with PISCES IV in the Bay D'Espoir fiord system of southern Newfoundland revealed a rich and abundant fauna inhabiting the rock walls in the warm deep (790 m) central basin. The giant file clam Acesta excavata, otherwise... more
Research dives with PISCES IV in the Bay D'Espoir fiord system of southern Newfoundland revealed a rich and abundant fauna inhabiting the rock walls in the warm deep (790 m) central basin. The giant file clam Acesta excavata, otherwise unknown in the western North Atlantic, was in many places a dominant species. Species otherwise known from continental slope depths quite removed from the fiord included the anemone Actinauge sp., sponges, alcyonarians, the fish Phycis chesteri and Nezumia bairdii and the gooseneck barnacle Arcoscalpellum mitchellotlanum.
The food source for this abundant fauna is unknown. Nearby cold water basins are impoverished with respect to the fauna.
The food source for this abundant fauna is unknown. Nearby cold water basins are impoverished with respect to the fauna.
Research Interests:
The life history and fecundity of five shallow-water lysianassoids from the Saint Lawrence Estuary were examined. Orchomenella minuta and Or. pinguis are annual and iteroparous (two broods), Psammonyx terranovae is iteroparous (two... more
The life history and fecundity of five shallow-water lysianassoids from the Saint Lawrence Estuary were examined. Orchomenella minuta and Or. pinguis are annual and iteroparous (two broods), Psammonyx terranovae is iteroparous (two broods) and probably biennial, and Anonyx sarsi and Onisimus litoralis are biennial and semelparous. Females of A. sarsi and On. litoralis cease feeding on bait shortly before or after oviposition, whereas females of the iteroparous Or. pinguis stop feeding on bait only when broods are in the latest stages of embryo development. These ontogenetic changes may result from gut constriction caused by developing ovaries and broods, or may be due to behavioural changes. Data on the fecundity of the Lysianassoidea are reviewed, and it is concluded that deep-living species are probably much less fecund than shallow-living species. Anonyx nugax, Or. pinguis, and A. sarsi are more fecund than other lysianassoids, possibly because of their high-risk carrion-feeding and suprabenthic foraging activities.
Research Interests:
Photographic transects were used to investigate the distribution of megafauna in relation to substrate variability on the outer Grand Banks. Sedimentary cover consisted of reworked glacial deposits arranged in alternating bands of gravel... more
Photographic transects were used to investigate the distribution of megafauna in relation to substrate variability on the outer Grand Banks. Sedimentary cover consisted of reworked glacial deposits arranged in alternating bands of gravel and sand. Megafaunal density was higher along transects with elevational gradients of l m km-1 than along transects with less gradient. Sessile, discretely motde, crawling, and swimming animals were spahally autocorrelated as Indicated by significant increase in variability with increase in length scale. Cross-correlation with substrate was stronger at large 100 m) than at smaller spatial scales in sessile, discretely motile, crawhng, and swimming animals. Local decoupling from substrate features was observed in swimming animals. Our results were consistent with the hypothesis that mobhty determines the spatial scales over which the densities of benthic organisms are associated with substrate variability.
Research Interests:
The North Water Polynya is an area of high biological activity that supports large numbers of higher trophic-level organisms such as seabirds and marine mammals. An overall objective of the Upper Trophic-Level Group of the International... more
The North Water Polynya is an area of high biological activity that supports large numbers of higher trophic-level organisms such as seabirds and marine mammals. An overall objective of the Upper Trophic-Level Group of the International North Water Polynya Study (NOW) was to evaluate carbon and contaminant flux through these high trophic-level (TL) consumers. Crucial to an evaluation of the role of such consumers, however, was the establishment of primary trophic linkages within the North Water food web. We used d15N values of food web components from particulate organic matter (POM) through polar bears (Ursus maritimus) to create a trophic-level model based on the assumptions that Calanus hyperboreus occupies TL 2.0 and there is a 2.4%trophic enrichment in 15N between birds and their diets, and a 3.8% trophic enrichment for all other components. This model placed the planktivorous dovekie (Alle alle) at TL 3.3, ringed seal (Phoca hispida) at TL 4.5, and polar bear at TL 5.5. The copepods C. hyperboreus, Chiridius
glacialis and Euchaeta glacialis formed a trophic continuum (TL 2.0–3.0) from primary herbivore through omnivore to primary carnivore. Invertebrates were generally sorted according to planktonic, benthic and epibenthic feeding groups. Seabirds formed three trophic groups, with dovekie occupying the lowest, black-legged kittiwake (Rissa tridactyla), northern fulmar (Fulmarus glacialis), thick-billed murre (Uria aalge), and ivory gull (Pagophilia eburnea) intermediate
(TL 3.9–4.0), and glaucous gull (Larus hyperboreus) the highest (TL 4.6) trophic positions. Among marine mammals, walrus (Odobenus rosmarus) occupied the lowest (TL 3.2) and bearded seal (Erignathus barbatus), ringed seal, beluga whale (Delphinapterus leucas), and narwhal (Monodon monoceros) intermediate positions (TL 4.1–4.6). In addition to arctic cod (Boreogadus saida), we suggest that lower trophic-level prey, in particular the amphipod Themisto libellula, contribute fundamentally in transferring energy and carbon flux to higher trophic-level seabirds and marine mammals. We measured PCB 153 among selected organisms to investigate the behavior of bioaccumulating contaminants within the food web. Our isotopic model confirmed the trophic magnification of PCB 153 in this high-Arctic food web due to a strong correlation between contaminant concentration and organism d15N values, demonstrating the utility of combining isotopic and contaminant approaches to food-web studies. Stable-carbon isotope analysis confirmed an enrichment in 13C between POM and ice algae (–22.3 vs. –17.7%). Benthic organisms were generally enriched in 13C compared to pelagic species. We discuss individual species isotopic data and the general utility of our stable isotope model for defining carbon flux and contaminant flow through the North Water food web.
glacialis and Euchaeta glacialis formed a trophic continuum (TL 2.0–3.0) from primary herbivore through omnivore to primary carnivore. Invertebrates were generally sorted according to planktonic, benthic and epibenthic feeding groups. Seabirds formed three trophic groups, with dovekie occupying the lowest, black-legged kittiwake (Rissa tridactyla), northern fulmar (Fulmarus glacialis), thick-billed murre (Uria aalge), and ivory gull (Pagophilia eburnea) intermediate
(TL 3.9–4.0), and glaucous gull (Larus hyperboreus) the highest (TL 4.6) trophic positions. Among marine mammals, walrus (Odobenus rosmarus) occupied the lowest (TL 3.2) and bearded seal (Erignathus barbatus), ringed seal, beluga whale (Delphinapterus leucas), and narwhal (Monodon monoceros) intermediate positions (TL 4.1–4.6). In addition to arctic cod (Boreogadus saida), we suggest that lower trophic-level prey, in particular the amphipod Themisto libellula, contribute fundamentally in transferring energy and carbon flux to higher trophic-level seabirds and marine mammals. We measured PCB 153 among selected organisms to investigate the behavior of bioaccumulating contaminants within the food web. Our isotopic model confirmed the trophic magnification of PCB 153 in this high-Arctic food web due to a strong correlation between contaminant concentration and organism d15N values, demonstrating the utility of combining isotopic and contaminant approaches to food-web studies. Stable-carbon isotope analysis confirmed an enrichment in 13C between POM and ice algae (–22.3 vs. –17.7%). Benthic organisms were generally enriched in 13C compared to pelagic species. We discuss individual species isotopic data and the general utility of our stable isotope model for defining carbon flux and contaminant flow through the North Water food web.
Research Interests:
Résumé La liste des noms français, anglais et latins des 55 espèces de mulettes du Canada (Ordre : Unionoida, Familles : Margaritiféridés et Unionidés) retrouvées jusqu’à présent a été mise à jour. Ce travail fait suite à l’ouvrage... more
Résumé
La liste des noms français, anglais et latins des 55 espèces de mulettes du Canada (Ordre : Unionoida, Familles : Margaritiféridés et Unionidés) retrouvées jusqu’à présent a été mise à jour. Ce travail fait suite à l’ouvrage classique de Arthur H. Clarke (1981), Mollusques d’eau douce du Canada-Freshwater Molluscs of Canada. La présente révision de la nomenclature française de même que la mise à jour de la liste des noms anglais et latins s’avéraient nécessaires compte tenu (I) des nombreuses révisions taxonomiques survenues depuis la parution de l'ouvrage de Clarke, (II) de la présence d'espèces nouvelles pour le Canada, et plus particulièrement (III) de l'existence de certains noms français devenus inappropriés, erronés ou portant à confusion. Une liste mise à jour des noms de mulettes canadiennes est d’autant plus utile aujourd’hui que cette faune est sérieusement en déclin et fait maintenant l’objet de plus en plus de recherche et d’inventaires partout au Canada. Les auteurs espèrent que la publication de cette liste, particulièrement en ce qui a trait aux noms français, contribuera à faire découvrir une composante importante de la faune aquatique canadienne, qui comporte malheureusement un nombre de plus en plus grand d’espèces rares ou menacées de disparition.
La liste des noms français, anglais et latins des 55 espèces de mulettes du Canada (Ordre : Unionoida, Familles : Margaritiféridés et Unionidés) retrouvées jusqu’à présent a été mise à jour. Ce travail fait suite à l’ouvrage classique de Arthur H. Clarke (1981), Mollusques d’eau douce du Canada-Freshwater Molluscs of Canada. La présente révision de la nomenclature française de même que la mise à jour de la liste des noms anglais et latins s’avéraient nécessaires compte tenu (I) des nombreuses révisions taxonomiques survenues depuis la parution de l'ouvrage de Clarke, (II) de la présence d'espèces nouvelles pour le Canada, et plus particulièrement (III) de l'existence de certains noms français devenus inappropriés, erronés ou portant à confusion. Une liste mise à jour des noms de mulettes canadiennes est d’autant plus utile aujourd’hui que cette faune est sérieusement en déclin et fait maintenant l’objet de plus en plus de recherche et d’inventaires partout au Canada. Les auteurs espèrent que la publication de cette liste, particulièrement en ce qui a trait aux noms français, contribuera à faire découvrir une composante importante de la faune aquatique canadienne, qui comporte malheureusement un nombre de plus en plus grand d’espèces rares ou menacées de disparition.
Research Interests:
Research Interests:
The primary purpose of our report is to examine the potential for establishing a program of artificial propagation for cod in Newfoundland somewhat along the lines of one that existed more than a hundred years ago on Dildo Island, Trinity... more
The primary purpose of our report is to examine the potential for establishing a program of artificial propagation for cod in Newfoundland somewhat along the lines of one that existed more than a hundred years ago on Dildo Island, Trinity Bay. Several considerations are investigated with respect to the history of this method as applied to marine fish and the reasons for its eventual abandonment by most countries, including Newfoundland. While concentrating on activities at the Dildo hatchery, the present investigation also reviews cod-propagation programs carried out by other countries during the same period. Finally, progress made in this field by Norwegian fisheries scientists since the beginning of their hatchery operations, almost no years ago, are taken into consideration. These advances have important bearing on the
orientation that an artificial propagation program might take in Newfoundland.
orientation that an artificial propagation program might take in Newfoundland.
Research Interests:
The bottom water in the > 300 m deep Lower St. Lawrence Estuary (LSLE) is persistently hypoxic in contrast to the norm oxic bottom waters in the Gulf ofSt. Lawrence (GSL). We photographed the seabed at 11 stations in the Estuary and Gulf... more
The bottom water in the > 300 m deep Lower St. Lawrence Estuary (LSLE) is persistently hypoxic in contrast to the norm oxic bottom waters in the Gulf ofSt. Lawrence (GSL). We photographed the seabed at 11 stations in the Estuary and Gulf of St. Lawrence (EGSL) during the summers 2006 and 2007 and analysed the images to identify bioturbation traces (lebensspuren) and benthic macrofauna. The objective was to identify the environmental variables that influence the density and diversity of benthic
macrofauna and bioturbation traces, and the differences that exist among regions with high, medium and low oxygen levels in the bottom water. The bottom water oxygen concentration is the variable that best explains the densities of total-traces as well as surface-traces. However, the density of these traces was higher in hypoxic regions than in well-oxygenated regions. The higher density of traces in the hypoxic region of the LSLE is mainly due to the activities of the surface deposit feeder Ophiura sp., which occurs in large numbers in this region. Possible explanations explored are stress behaviour of the organisms in response to hypoxia and different benthic macrofauna community structures between the
hypoxic regions of the LSLE and the normoxic regions of the GSL. In the former, surface deposit feeders and low-oxygen tolerant species dominate over suspension feeclers and low-oxygen intolerant species.
macrofauna and bioturbation traces, and the differences that exist among regions with high, medium and low oxygen levels in the bottom water. The bottom water oxygen concentration is the variable that best explains the densities of total-traces as well as surface-traces. However, the density of these traces was higher in hypoxic regions than in well-oxygenated regions. The higher density of traces in the hypoxic region of the LSLE is mainly due to the activities of the surface deposit feeder Ophiura sp., which occurs in large numbers in this region. Possible explanations explored are stress behaviour of the organisms in response to hypoxia and different benthic macrofauna community structures between the
hypoxic regions of the LSLE and the normoxic regions of the GSL. In the former, surface deposit feeders and low-oxygen tolerant species dominate over suspension feeclers and low-oxygen intolerant species.
Research Interests:
In times of economic constraint, collection-holding institutions world-wide face similar challenges. Among critical issues of concern is the need to marry a decrease in resources and the growing numbers of orphaned collections with... more
In times of economic constraint, collection-holding institutions world-wide face similar challenges. Among critical issues of concern is the need to marry a decrease in resources and the growing numbers of orphaned collections with continual requests for new acquisitions. The result is a pressing need to improve the quality and efficiency of collection management, and particularly collecting. An initial and essential step to the elaboration of any national or international strategy on issues such as collection development is the examination of present collections: that is, where they are and what they contain. To achieve this in Canada, information on natural sciences collections was compiled from specific survey reports and collection indexes.
Research Interests:
Two large bivalve specimens collected in Bay d'Espoir, a deep fjord situated on the south coast of Newfoundland, are described and identified as belonging to the species Acesta excavata (Fabricius 1779). In situ observations onboard the... more
Two large bivalve specimens collected in Bay d'Espoir, a deep fjord situated on the south coast of Newfoundland, are described and identified as belonging to the species Acesta excavata (Fabricius 1779). In situ observations onboard the manned submersible PISCES IV and color videos have provided information on the vertical distribution, density and habitat of the species. Maximum abundances of about 15 large individuals/m2 occurred on sheltered rock outcrops at depth ranging from 550 to 775 m, where warm (6°C) continental slope water is found. Differences in shape and thickness between the valves of the two specimens appear to be related to the degree of exposure to rock falls (i.e., sheltered versus exposed habitat). Prior to this account, the European Giant File Clam had never been encountered west of the Azores Islands in the
North Atlantic.
North Atlantic.
Research Interests:
The biology and ecology of the sea urchin Strongylocentrotus pallidus was studied using photographic transects and collected specimens from the Grand Bank of Newfoundland. Specimens measured from photographs along two transects showed... more
The biology and ecology of the sea urchin Strongylocentrotus pallidus was studied using photographic transects and collected specimens from the Grand Bank of Newfoundland. Specimens measured from photographs along two transects showed mean
diameters of 36.2 ± 7.2 rom and 31.9 ± 4.9 rom. Urchins greater than 50 rom were rare. Maximum density was 5 individuals per m2• Mean biomass estimates along transects ranged from 0.23 g/m2 to 9.92 g/m2. Overall mean gonad index was 4.9% for specimens collected in November below 70 m. There was no trend in G.I. with depth or station location. Gut analysis revealed an omnivorous diet with evidence of grazing on both sand and cobble substrates. Sea urchins occurred more frequently on mixed cobble-sand substrates than on sand or predominantly (>80%) cobble substrates. It is speculated that mixed cobble-sand substrates provide both mechanical stability for urchins as well as an optimum, varied
substrate for feeding.
diameters of 36.2 ± 7.2 rom and 31.9 ± 4.9 rom. Urchins greater than 50 rom were rare. Maximum density was 5 individuals per m2• Mean biomass estimates along transects ranged from 0.23 g/m2 to 9.92 g/m2. Overall mean gonad index was 4.9% for specimens collected in November below 70 m. There was no trend in G.I. with depth or station location. Gut analysis revealed an omnivorous diet with evidence of grazing on both sand and cobble substrates. Sea urchins occurred more frequently on mixed cobble-sand substrates than on sand or predominantly (>80%) cobble substrates. It is speculated that mixed cobble-sand substrates provide both mechanical stability for urchins as well as an optimum, varied
substrate for feeding.
Research Interests:
A functional approach based on feeding type. microhabitat preference, motility pattern, and body size of benthic organisms is compared to a taxonomic (family) based method in the study of the trophodynamics of marine soft-bottom... more
A functional approach based on feeding type. microhabitat preference, motility pattern, and body size of benthic organisms is compared to a taxonomic (family) based method in the study of the trophodynamics of marine soft-bottom communities. Grab samples were collected from the continental shelf and slope along the east coast of Canada at depths ranging from 85 to 622 m (x = 247 m). Canonical multivariate analysis was used to produce functional and taxonomic classifications of macrofaunal polychaete assemblages that were correlated with environmental variables. No distinct faunal associations were identified from either approach. Instead there
appeared to be a continuum of faunal groups. Groups of samples along the continuum appeared to be loosely associated with large-scale topographic features of the Labrador shelf and slope. Nearly
50% of the variation in the biological data was explained by environmental variables such as water depth , station latitude, and sediment grain size. The functional approach provided a more direct
way of interpreting the effects of environmental factors on the community structure. The way in which the biological and environmental data are collected influences the outcome of multivariate analysis and its interpretation .
appeared to be a continuum of faunal groups. Groups of samples along the continuum appeared to be loosely associated with large-scale topographic features of the Labrador shelf and slope. Nearly
50% of the variation in the biological data was explained by environmental variables such as water depth , station latitude, and sediment grain size. The functional approach provided a more direct
way of interpreting the effects of environmental factors on the community structure. The way in which the biological and environmental data are collected influences the outcome of multivariate analysis and its interpretation .
Research Interests:
Evaluating and understanding biodiversity in marine ecosystems are both necessary and challenging for conservation. This paper compiles and summarizes current knowledge of the diversity of marine taxa in Canada's three oceans while... more
Evaluating and understanding biodiversity in marine ecosystems are both necessary and challenging for conservation. This paper compiles and summarizes current knowledge of the diversity of marine taxa in Canada's three oceans while recognizing that this compilation is incomplete and will change in the future. That Canada has the longest coastline in the world and incorporates distinctly different biogeographic provinces and ecoregions (e.g., temperate through ice-covered areas) constrains this analysis. The taxonomic groups presented here include microbes, phytoplankton, macroalgae, zooplankton, benthic infauna, fishes, and marine mammals. The minimum number of species or taxa compiled here is 15,988 for the three Canadian oceans. However, this number clearly underestimates in several ways the total number of taxa present. First, there are significant gaps in the published literature. Second, the diversity of many habitats has not been compiled for all taxonomic groups (e.g., 1intertidal rocky shores, deep sea), and data compilations are based on short-term, directed research programs or longer-term monitoring activities with limited spatial resolution. Third, the biodiversity of large organisms is well known, but this is not true of smaller organisms. Finally, the greatest constraint on this summary is the willingness and capacity of those who collected the data to make it available to those interested in biodiversity meta-analyses. Confirmation of identities and intercomparison of studies are also constrained by the disturbing rate of decline in the number of taxonomists and systematists specializing on marine taxa in Canada. This decline is mostly the result of retirements of current specialists and to a lack of training and employment opportunities for new ones. Considering the difficulties encountered in compiling an overview of biogeographic data and the diversity of species or taxa in Canada's three oceans, this synthesis is intended to serve as a biodiversity baseline for a new program on marine biodiversity, the Canadian Healthy Ocean Network. A major effort needs to be undertaken to establish a complete baseline of Canadian marine biodiversity of all taxonomic groups, especially if we are to understand and conserve this part of Canada's natural heritage.
Research Interests:
Functional approaches are introduced to study the structure of marine soft bottom communities. Results of these approaches, based on the feeding type, microhabitat preference, motility pattern and body size of benthic polychaetes, were... more
Functional approaches are introduced to study the structure of marine soft bottom communities. Results of these approaches, based on the feeding type, microhabitat preference, motility pattern and body size of benthic polychaetes, were compared to one based on taxonomy (families). The material came from grab samples collected from the continental shelf and upper slope off the east coast of Canada, in depths of 85 to 622 m (~ =247 m). Various multivariate analyses are used to identify recurrent biological patterns in macrofaunal assemblages. These patterns are then correlated with environmental variables via canonical analysis. No distinct faunal associations are identified from the various approaches. Instead, there was a gradual shift from one type of faunal grouping to another.
The value of each approach in characterizing community structure is
evaluated in part by the amount of variation explained by the relationship
between the biological and environmental data, and by the statistical
significance of this relationship as determined by Monte Carlo tests. The
recognition of homogeneous groupings of samples based on faunal composition and environmental conditions, however, tends to weigh more heavily in this evaluation. With one exception, all functional and taxonomic approaches show statistically significant patterns. The approach based on feeding microhabitat indicates that this biological attribute of marine benthic polychaetes may not play an important role in the structuring of their communities. The functional approach that comprises all functional attributes (i.e. foraging attributes and body size) provides the most meaningful ecological characterization of
community structure. In this functional approach, groups of samples along the faunal gradients are strongly associated with large-scale topographic features of the Labrador continental shelf and upper slope. Although the taxonomic approach yields similar results, it does not appear to be as efficient in distinguishing between sample points in multivariate analyses. In functional approaches, interpretation of the results in terms of community structure is greatly facilitated by the direct use of ecological attributes such as foraging mode and body size.
About half the variation in the biological data can be explained by variables such as water depth, current regime, sediment grain size and benthic biomasses which are associated with two major environmental gradients extracted by Redundancy Analysis. The effect of other biotic and abiotic factors on benthic community structure is discussed. The remaining variability in the biological data unaccounted for in this study may be explained by these factors, other unidentified processes and noise. The spatial scales at which the biological and environmental data are collected may also influence the outcome of a multivariate analysis and its interpretation.
The value of each approach in characterizing community structure is
evaluated in part by the amount of variation explained by the relationship
between the biological and environmental data, and by the statistical
significance of this relationship as determined by Monte Carlo tests. The
recognition of homogeneous groupings of samples based on faunal composition and environmental conditions, however, tends to weigh more heavily in this evaluation. With one exception, all functional and taxonomic approaches show statistically significant patterns. The approach based on feeding microhabitat indicates that this biological attribute of marine benthic polychaetes may not play an important role in the structuring of their communities. The functional approach that comprises all functional attributes (i.e. foraging attributes and body size) provides the most meaningful ecological characterization of
community structure. In this functional approach, groups of samples along the faunal gradients are strongly associated with large-scale topographic features of the Labrador continental shelf and upper slope. Although the taxonomic approach yields similar results, it does not appear to be as efficient in distinguishing between sample points in multivariate analyses. In functional approaches, interpretation of the results in terms of community structure is greatly facilitated by the direct use of ecological attributes such as foraging mode and body size.
About half the variation in the biological data can be explained by variables such as water depth, current regime, sediment grain size and benthic biomasses which are associated with two major environmental gradients extracted by Redundancy Analysis. The effect of other biotic and abiotic factors on benthic community structure is discussed. The remaining variability in the biological data unaccounted for in this study may be explained by these factors, other unidentified processes and noise. The spatial scales at which the biological and environmental data are collected may also influence the outcome of a multivariate analysis and its interpretation.
Research Interests:
Research Interests:
Ice cover, food availability, light intensity, limited dispersal capacity, presence of predators and reproduction mode are just a few of the drivers that influence benthic community dynamics, especially in the Arctic. Benthic organisms... more
Ice cover, food availability, light intensity, limited dispersal capacity, presence of predators and reproduction mode are just a few of the drivers that influence benthic community dynamics, especially in the Arctic. Benthic organisms can respond to such drivers through morphologic variations, referred to as phenotypic plasticity. These variations are however hard to observe on Arctic whelk (genus Buccinum) and their diversity and extensive distribution increase the complexity of their identification. While genetics analyses can address this problem, they are not broadly accessible. More accessible are landmark-based geometric morphometrics which analytically identifies morphologic variations. This technique aims at identifying shape variations and could be used to identify intra-and inter-species morphologic variability in the genus Buccinum. The main objective of this project is to verify whether landmark-based geometric morphometrics, particularly 3-dimensional, could be used on whelk species. If this proof of concept proves successful, the next step will be to identify new morphologic traits to differentiate species and compare this technique to genetics analyses on multiple Buccinum species. This project could allow researchers to efficiently differentiate between whelk species on the basis of morphologic traits rather than through more demanding genetics analyses.