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SIZE, STRUCTURE AND FUNCTIONALITY IN SHALLOW COVE COMMUNITIES IN RI
Citation:
Chintala, M AND L Meng. SIZE, STRUCTURE AND FUNCTIONALITY IN SHALLOW COVE COMMUNITIES IN RI. Presented at Southern New England Chapter of the American Fisheries Society, Old Lyme, CT, June 14, 2000.
Description:
We are using an ecosystem approach to examine the ecological integrity and important habitats in small estuarine coves. We sampled the small undeveloped Coggeshall Cove during the sununer of 1999. The cove was sampled at high tide at every 15 cm of substrate elevation along transects from the marsh surface to the deeper subtidal areas of the cove. The gear used to sample was a 1.75 m2 drop ring for small nekton that included crabs, shrimp and fishes. Along this transect, the habitat changes from a structurally complex intertidal marsh surface to the less structurally complex intertidal area, back to the more structurally complex macroalgal subtidal area. The main crab, fish and shrimp species were separated into size frequency distributions within each of the habitats to determine if different size structures existed since size structure can complement taxonomic information to describe community and environmental interactions. All of the organisms were classified based on their feeding habits to try and interpret the patterns in community structure and the ecological forces that may cause changes in distibution, abundance and diversity. Our hypothesis was that more complex size structures of organisms and the more functional groups of organisms (as determined by feeding mode) would be found in the more complex habitats. For Carcinus maenus, Fundulus heteroclitus and Palaemonetes spp., the two marsh surface and subtidal areas (more structurally complex) had similar size structures, with a diversity of sizes present in each habitat; however, more smaller sized F heteroclitus were found in the subtidal than in the marsh habitat. Relatively few of these species were found in the intertidal area, making the comparison with habitat complexity difficult. In contrast, the majority of Pagurus longicarpus, the hermit crab, were found in the intertidal area. This species relies on its outer shell rather than on the plant structure for predator refuge. In determining the abundant functional group in a habitat, the abundance metric used makes a difference. For all habitats, there were more omnivores by density per m-2, but more predators by biomass per m-2. C. maenus was the biomass dominant predator in both the marsh and subtidal habitats while Palaemonetes spp. were the dominant omnivores in the subtidal habitat. Surprisingly, the dominant predator of invertebrates in the marsh as well as the intertidal habitats was the flounder, Pseudopleuronectes american us. These results suggest that the macroalgal subtidal areas can be just as important as the vegetated areas in a cove system.