Gulf of Mexico (GOM) ecosystems are interconnected by numerous physical and biological processes.... more Gulf of Mexico (GOM) ecosystems are interconnected by numerous physical and biological processes. After the Deepwater Horizon (DWH) disaster, these ecological processes facilitated dispersal of oil-spill toxicants or were damaged and broken. A considerable portion of post-DWH research focused on higher levels of biological organization (i.e., populations, communities, and ecosystems) spanning at least four environments (onshore, coastal, open ocean, and deep benthos). Damage wrought by the oil spill and mitigation efforts varied considerably across ecosystems. Whereas all systems show prolonged impacts because of cascading effects that impacted functional connections within and between communities, deep-sea and mesopelagic environments were particularly hard hit and have shown less resilience than shallow environments. In some environments, such as marshes or the deep-sea benthos, products from the spill are still biologically accessible. Some shallow ecosystems show signs of recove...
Page 1. American Journal of Botany 83(12): 1521-1527. 1996. INTRASPECIFIC VARIATION IN SALT TOLER... more Page 1. American Journal of Botany 83(12): 1521-1527. 1996. INTRASPECIFIC VARIATION IN SALT TOLERANCE AND MORPHOLOGY IN THE COASTAL GRASS SPARTINA PATENS (POACEAE)1 MARK W. HESTER,2 IRVING A. MENDELSSOHN, AND KAREN L. MCKEE ...
Page 1. Int. J. Plant Sci. 159(l):127-138. 1998. ?) 1998 by The University of Chicago. All rights... more Page 1. Int. J. Plant Sci. 159(l):127-138. 1998. ?) 1998 by The University of Chicago. All rights reserved. 1058-5893/98/5901-0016$03.00 INTRASPECIFIC VARIATION IN SALT TOLERANCE AND MORPHOLOGY IN PANICUM ...
Environmental and Experimental Botany, Dec 1, 2001
Panicum hemitomon, Spartina patens, and Spartina alterniflora are wide-spread dominant grasses of... more Panicum hemitomon, Spartina patens, and Spartina alterniflora are wide-spread dominant grasses of fresh, brackish, and salt marsh plant communities, respectively. Our previous research identified significant intraspecific variation in salt tolerance and morphology among populations within each species. In this study our objectives were to determine shorter-term physiological/biochemical responses to salinity stress and identify potential indicators of salt tolerance, with the
Clones of Spartina patens were collected from 19 locations throughout Gulf coast marshes of Texas... more Clones of Spartina patens were collected from 19 locations throughout Gulf coast marshes of Texas, Louisiana, and Florida. Following three vegetative generations of de-acclimation from field conditions, genotypes were subjected to a salinity screening protocol in which salinity was increased in weekly increments of 5%o (gram salt/kilogram solution). Plants were harvested when there was 50% death of aboveground tissue, which we defined as the lethal salinity level. The genotypes displayed highly significant intraspecific variation in lethal salinity level, which ranged from 63%o to 93%o. Significant intraspecific variation was also observed in all plant morphological variables, as well as leaf rolling, leaf expansion rates at 2%o and 20%o salinity, aboveground, belowground, and total biomass, and belowground-to-aboveground biomass ratio. An ANOVA of principal component scores from a PCA of lethal salinity level and covariable-adjusted total plant dry mass further illustrated intraspecific variation within this species in these two traits expressed as one principal component. Correlation analysis revealed that intraspecific variation in salt tolerance was not strongly associated with intraspecific variation in plant morphological traits, leaf rolling, or leaf expansion rates.
Soil redox potentials and pore water sulfide concentrations on a mangrove island in the Belizean ... more Soil redox potentials and pore water sulfide concentrations on a mangrove island in the Belizean barrier reef system were significantly correlated with the presence of the aerial roots of mangrove trees. Sulfide concentrations were three to five times lower near the prop roots of Rhizophora mangle (red mangrove) and the pneumatophores of Avicennia germinans (black mangrove) than in adjacent (? 1 meter away) unvegetated sediment. Soil redox potentials were also significantly higher near the aerial roots. A comparison of the two species revealed that sulfide concentrations in the rhizosphere of R. mangle were as low as that of A. germinans. However, sulfide concentrations in areas occupied by the black mangrove were variable and a function of pneumatophore density. The occurrence of an oxidized rhizosphere around the roots of both species suggests that the adult trees are equally capable of exploiting reduced sediments as long as their respective pathways for root aeration are functional. RHIZOPHORA MANGLE L. and Avicennia germinans (L.) L. are dominant mangrove species of neotropical intertidal regions where they sometimes occur in monospecific zones. In the Caribbean region, R. mangle is typically found in regularly flooded intertidal areas and A. germinans in areas farther inland at higher ele
Gulf of Mexico (GOM) ecosystems are interconnected by numerous physical and biological processes.... more Gulf of Mexico (GOM) ecosystems are interconnected by numerous physical and biological processes. After the Deepwater Horizon (DWH) disaster, these ecological processes facilitated dispersal of oil-spill toxicants or were damaged and broken. A considerable portion of post-DWH research focused on higher levels of biological organization (i.e., populations, communities, and ecosystems) spanning at least four environments (onshore, coastal, open ocean, and deep benthos). Damage wrought by the oil spill and mitigation efforts varied considerably across ecosystems. Whereas all systems show prolonged impacts because of cascading effects that impacted functional connections within and between communities, deep-sea and mesopelagic environments were particularly hard hit and have shown less resilience than shallow environments. In some environments, such as marshes or the deep-sea benthos, products from the spill are still biologically accessible. Some shallow ecosystems show signs of recove...
Page 1. American Journal of Botany 83(12): 1521-1527. 1996. INTRASPECIFIC VARIATION IN SALT TOLER... more Page 1. American Journal of Botany 83(12): 1521-1527. 1996. INTRASPECIFIC VARIATION IN SALT TOLERANCE AND MORPHOLOGY IN THE COASTAL GRASS SPARTINA PATENS (POACEAE)1 MARK W. HESTER,2 IRVING A. MENDELSSOHN, AND KAREN L. MCKEE ...
Page 1. Int. J. Plant Sci. 159(l):127-138. 1998. ?) 1998 by The University of Chicago. All rights... more Page 1. Int. J. Plant Sci. 159(l):127-138. 1998. ?) 1998 by The University of Chicago. All rights reserved. 1058-5893/98/5901-0016$03.00 INTRASPECIFIC VARIATION IN SALT TOLERANCE AND MORPHOLOGY IN PANICUM ...
Environmental and Experimental Botany, Dec 1, 2001
Panicum hemitomon, Spartina patens, and Spartina alterniflora are wide-spread dominant grasses of... more Panicum hemitomon, Spartina patens, and Spartina alterniflora are wide-spread dominant grasses of fresh, brackish, and salt marsh plant communities, respectively. Our previous research identified significant intraspecific variation in salt tolerance and morphology among populations within each species. In this study our objectives were to determine shorter-term physiological/biochemical responses to salinity stress and identify potential indicators of salt tolerance, with the
Clones of Spartina patens were collected from 19 locations throughout Gulf coast marshes of Texas... more Clones of Spartina patens were collected from 19 locations throughout Gulf coast marshes of Texas, Louisiana, and Florida. Following three vegetative generations of de-acclimation from field conditions, genotypes were subjected to a salinity screening protocol in which salinity was increased in weekly increments of 5%o (gram salt/kilogram solution). Plants were harvested when there was 50% death of aboveground tissue, which we defined as the lethal salinity level. The genotypes displayed highly significant intraspecific variation in lethal salinity level, which ranged from 63%o to 93%o. Significant intraspecific variation was also observed in all plant morphological variables, as well as leaf rolling, leaf expansion rates at 2%o and 20%o salinity, aboveground, belowground, and total biomass, and belowground-to-aboveground biomass ratio. An ANOVA of principal component scores from a PCA of lethal salinity level and covariable-adjusted total plant dry mass further illustrated intraspecific variation within this species in these two traits expressed as one principal component. Correlation analysis revealed that intraspecific variation in salt tolerance was not strongly associated with intraspecific variation in plant morphological traits, leaf rolling, or leaf expansion rates.
Soil redox potentials and pore water sulfide concentrations on a mangrove island in the Belizean ... more Soil redox potentials and pore water sulfide concentrations on a mangrove island in the Belizean barrier reef system were significantly correlated with the presence of the aerial roots of mangrove trees. Sulfide concentrations were three to five times lower near the prop roots of Rhizophora mangle (red mangrove) and the pneumatophores of Avicennia germinans (black mangrove) than in adjacent (? 1 meter away) unvegetated sediment. Soil redox potentials were also significantly higher near the aerial roots. A comparison of the two species revealed that sulfide concentrations in the rhizosphere of R. mangle were as low as that of A. germinans. However, sulfide concentrations in areas occupied by the black mangrove were variable and a function of pneumatophore density. The occurrence of an oxidized rhizosphere around the roots of both species suggests that the adult trees are equally capable of exploiting reduced sediments as long as their respective pathways for root aeration are functional. RHIZOPHORA MANGLE L. and Avicennia germinans (L.) L. are dominant mangrove species of neotropical intertidal regions where they sometimes occur in monospecific zones. In the Caribbean region, R. mangle is typically found in regularly flooded intertidal areas and A. germinans in areas farther inland at higher ele
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