Latitudinal gradients in benthic community composition in Western Atlantic estuaries
AimThe community composition of benthic macroinvertebrates from 295 estuarine sites was examined in order to either confirm or challenge established boundaries of zoogeographical provinces. We also investigated the postulate that, while local distributions were determined by natural habitat characteristics such as salinity, sediment type and depth, distributions on a large geographical scale would be correlated with temperature.
LocationThe Atlantic coast of the United States (on a latitudinal gradient from 42° to 25°N).
MethodsUsing the descriptive techniques of cluster analysis and nonmetric multi-dimensional scaling, we determined the similarities in benthic community composition between sites within 1° latitudinal bands and compared the biotic ordinations to natural habitat characteristics such as salinity, sediment type and depth. We then evaluated the overall community composition within each 1° latitudinal band and established whether or not similarities existed between adjacent 1° latitudinal bands. In this manner, we were able to confirm that a latitudinal gradient existed in estuarine benthic community composition along the western Atlantic coast. This latitudinal gradient was demarcated by biogeographical boundaries at (1) Biscayne Bay, Florida, (2) the southern end of the Indian River Lagoon, Florida, (3) St John's River, Florida, (4) Cape Island, South Carolina, (5) the mouth of the Cape Fear River, North Carolina and (6) Cape Cod, Massachusetts, with a subprovince boundary just north of Cape May at Wildwood, New Jersey.
ResultsThe major divisions approximated widely recognized biogeographical boundaries. Average summer water temperatures correlated better than sediment type, depth, or salinity with the latitudinal groupings of sites determined by cluster analysis.
ConclusionsBased on this relationship, we speculate on the potential impacts of current global climate change scenarios on the distribution of benthic macroinvertebrates along the western Atlantic coast.
Document Type: Original Article
Affiliations: U. S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Gulf Ecology Division, 1 Sabine Island Drive, Gulf Breeze, Florida 32561 USA
Publication date: September 1, 1999