Invasion-Related Change in Crayfish Density Affects a Stream Macroinvertebrate Community

Abstract

Abstract Orconectes rusticus (Rusty Crayfish) have invaded streams of the upper Susquehanna River catchment, NY, replacing native crayfish and, in some areas, increasing overall crayfish density. Crayfish are important consumers and significant agents of disturbance in aquatic communities, so the introduction and expansion of Rusty Crayfish could affect the invaded community through the change in crayfish species composition, the increase in crayfish density, or some combination of the two. Other macroinvertebrates are prey of, competitors with, or subject to disturbance by crayfish and so are likely to be affected by changes in the crayfish assemblage. I conducted experiments in stream enclosures to determine the effects of crayfish species and density on the macroinvertebrate community. Increasing crayfish density reduced macroinvertebrate density but did not significantly affect macroinvertebrate taxon richness, diversity, or community composition. At moderate densities, the effects of native O. propin...