Date Awarded


Document Type


Degree Name

Doctor of Philosophy (Ph.D.)


Virginia Institute of Marine Science


Numerical classification analyses (clustering) of spring, summer and fall National Marine Fisheries Service bottom trawl catches on the inshore continental shelf between Cape Ann, Ma. and Cape Fear, N.C., showed consistent species associations and faunal zones over a three year period. Analysis of a data set created by combining all nine survey cruises also produced consistent species associations, however sites clustered by seasons as well as by geographic area. The three faunal provinces of the U.S. east coast (Gulf of Maine, Middle Atlantic Bight and South Atlantic Bight) were represented in the study area, as were the seasonal faunal barriers at Nantucket Shoals and Cape Hatteras. Generally, the faunal zones correlated well with the thermal regimes of each province and respected the faunal barriers when strong thermal gradients were present. Only south of Cape Hatteras did depth appear to define a boundary between faunal zones. During the spring, when bottom water temperatures were lowest, four species associations and three faunal zones were identified. The species associations consisted of a cold water boreal group (affiliated only with the faunal zone between Cape Ann and Cape May, N.J.), a less cryophilic boreal group, a eurythermal warm temperate group and a warm temperate group which was restricted to waters south of Cape Hatteras. With vernal warming, a northerly and onshore migration of warm temperate species increased to five the number of species associations in summer. Beside the four groups found in spring, a more thermophilic association was identified. Separations between the northern three summer faunal zones occurred at Nantucket Shoals and northern New Jersey. The other two summer zones were restricted to south of Cape Hatteras and were separated longitudinally (inshore and offshore). In fall, when bottom temperatures were highest, a sixth species group of primarily southern species was identified. This group appeared restricted to the inshore faunal zone south of Cape Hatteras. The five faunal zones recognized in summer were also identified in fall.



© The Author