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LATITUDINAL GRADIENTS IN BENTHIC COMMUNITY COMPOSITION IN WESTERN ATLANTIC ESTUARIES
Citation:
Engle, V D. AND J K. Summers. LATITUDINAL GRADIENTS IN BENTHIC COMMUNITY COMPOSITION IN WESTERN ATLANTIC ESTUARIES. Journal of Biogeography 26(5):1007-1023, (1999).
Description:
The community structure of benthic macroinvertebrates from estuaries along the Atlantic coast of North America from Cape Cod, MA, to Biscayne Bay, FL, were compared. Benthic data were collected over a 5 year period (1990 to 1995) by the U.S. Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP). We compared the community structure of estuarine benthos from 295 sites located between Cape Cod, MA, and Biscayne Bay, FL (on a latitudinal gradient from 42| to 25|N). Using the descriptive techniques of cluster analysis and nonmetric multidimensional scaling, we determined the similarities in benthic community structure between sites within 1| latitude bands and compared the biotic ordinations to natural habitat characteristics like salinity, sediment type, and depth. We then evaluated the overall community structure within each 1| latitude band and established whether or not similarities existed between adjacent 1| latitude bands. In this manner, we were able to confirm that a latitudinal gradient existed in estuarine benthic community structure along the western Atlantic coast. This latitudinal gradient was demarcated by biogeographical boundaries at (1) Biscayne Bay, FL, (2) the southern end of the Indian River Lagoon, FL, (3) St. Johns River, FL, (4) Cape Island, SC, (5) the mouth of the Cape Fear River, NC, and (6) Cape Cod, MA, with a subprovince boundary just north of Cape May at Wildwood, NJ. The major divisions approximated widely recognized provincial boundaries. Average summer water temperatures correlated better than sediment type, depth, or salinity with the latitudinal groupings of sites determined by cluster analysis. Based on this relationship, we speculated on the potential impacts of current global climate change scenarios on the distribution of benthic species along the western Atlantic coast.