Microhabitat selection and colonization rates of a benthic amphipod

Abstract

ABSTRACT: Microhabitat selechon behavior and colonization rates were examined for 2 age classes and sexes of the nocturnally emergent, diurnally tubicolous amphipod Microdeutopus gryllotalpa. Three habitat variables were stubed: food availability, sedlment thckness, and topograplc relief. Higher food concentration, deeper sedment, and greater topograplc relief were generally favored. Adult males and females made slmilar habitat choices, whereas juveniles were less discriminating. Both age classes colonized selected patches within 5 to 20 min of presentation to a cho~ce of habitats, and both generally sustained their choices for at least 72 h In the laboratory. Microhabitat selections m field experiments were similar to those in laboratory experiments. Field colonization rates of 0.06 and 0.17 amphlpods per day and night, respectively, were comparable to rates of larval and post- larval colonization reported in other studles. High rates of nocturnal rnobhty and colonization, and rapid discrimination of microhabitats observed in thls and other benthc species suggest that contem- porary models of benthic community structure need to incorporate these migratory and colonization behaviors as alternatives to mortality as responses to disturbance, competitors, or predators.