The presence or absence of higher-order interactions among aquatic cave crustaceans of the Greenbrier Valley, West Virginia

The purpose of this study was to determine the presence or absence of higher-order interactions among three amphipod crustacean species, Gammarus minus, Stygobromus emarginatus, and Stygobromus spinatus, and one isopod species, Caecidotea holsingeri. These isopod and amphipod species compete for space, preferring riffle to pools. In order to obtain information to detect higher-order interaction, the washout rates of several species combinations were measured using artificial stream experiments. First of all, each amphipod species and the isopod species was run at density of 10 in each of the streams. Secondly, the washout rate of each species in the presence of the other species was determined. Thirdly, three species combinations were run in the artificial streams. Higher-order effects were detected among S. emarginatus, G. minus, and G. holsingeri.