摘要：The invasive amphipod, Echinogammarus ischnus, has displaced the native amphipod, Gammarus fasciatus, at some locations within the Great Lakes. We examined the relationship between amphipod community structure and habitat characteristics in the field. Amphipod and algal samples were collected from four sites in western Lake Erie, during July, August, and September, 2004. Three distinct patterns in amphipod communities were observed. At a site dominated by invasive Dreissena mussels, only E. ischnus was present; however, at sites with rich filamentous or macrocolonial green algal communities, either both amphipods co-existed or only G. fasciatus was present. A strong correlation existed between G. fasciatus relative abundance and filamentous and macrocolonial green algal relative abundance. G. fasciatus appears to be better equipped to inhabit filamentous algae, whereas E. ischnus seems better adapted for areas dominated by Dreissena spp. Habitat characteristics, combined with niche differentiation and differential fish predation, may promote co-existence between G. fasciatus and E. ischnus within the Great Lakes.
