Colonization and succession of benthic macroinvertebrates in a new reservoir

The colonization and succession of benthic macroinvertebrates in the shallow areas (under 7 m) of Anna lake, a new mainstream impoundment in southeastern U.S.A. were studied. The lake was well colonized during the summer and immediately after impoundment. Major changes in fauna occurred in the first two years only and formed two distinct phases: colonization by species dependent on components of the former terrestrial ecosystem for food and habitat; as autochthonous factors regulated succession, increase in diversity and a shift in dominant species to an assemblage of second colonizers. Causes are outlined and include decomposition of terrestrial vegetation and detritus, sedimentation, improved food quality, increased plankton populations, and the appearance of macrophytes.