Certain invertebrates are more efficient than others in filtering solids from suspension. An equal degree of variability exists among benthic invertebrates in their ability to mix biodeposits into subsurface sediments. As a result of these differences, the degree to which suspended particulate matter and associated contaminants may be deposited or mixed into sediments may in part depend on the species present, which in turn may be dependent on sediment type. A number of investigators have examined the relation between benthic animal communities and their limiting physical factors (Smith, 1932; Mare, 1942; Dexter, 1947; Holm, 1949; Stic~1ey and Stringer, 1957; Sanders, 1956, 1958, 1960; and Jones, 1961). Except for studies on the effects of thermal effluents (Warinner and Brehmer, 1966) and the relation of the distribution of several species to sediment water (Harrison and Wass, 1965), little is known of such assemblages in the Chesapeake Bay.
In this report we will examine the faunal composition at four depths in the York River, Virginia, in terms of the number of species, number of individuals and biomass, and the influence of sediment parameters on these benthic communities
