The effect of sediment characteristics on the distribution of two subtidal harpacticoid copepod species

Abundances of two harpacticoid copepod species, Enhydrosoma littorale Wells and Zausodes c.f. arenicolus Wilson, were significantly higher in one of two adjacent subtidal, soft-bottom habitats in St. George Sound, Florida (29°54′N : 84°37′48′′W). For Enhydrosoma littorale, a laboratory-preference experiment indicated that sediment-related factors caused the observed distribution. In a series of preference experiments, differences between the sediments of the two habitats in granulometry and organic matter were shown not to account for the preference. Rather, the preference results from differences in the microbes attached to the sediment particles in the two areas. In contrast, Zausodes c.f. arenicolus did nol prefer sediments from its area of high field abundance in laboratory preference experiments, indicating that factors external to the sediment i.e. hydrographic conditions or biological interactions, were responsible for this species' distribution.