Benthic invertebrate colonization: source distance effects on community composition

Abstract

The trends in colonization and establishment of equilibrium benthic communities in a reclaimed coal strip-mined river channel were analyzed for 17 months after channel construction. The MacArthur-Wilson island colonization theories and an analysis of community composition by simultaneous daily comparisons between source and new channel communities were employed. Each downstream site attained an equilibrium condition at approximately twice the time required for a site 200 m closer to the upstream source area of drifting colonizers. When considering functional groups of aquatic invertebrates, the collector-gatherers and collector-filterers of detrital material were the initial colonizers. With respect to foraging habit, those invertebrates which were found commonly in the water column above the substrate, the swimmers and clingers, were found to be the initial colonizers of the most distant substrate islands. As habitat complexity increased, trophic complexity increased with priority of arrival and dispersal potential determined by trophic position and foraging habit. It is suggested that the Jaccard community association analysis be used to assess stable new community conditions. The index provides an indication in changes in diversity and density and can be compared with source area communities to determine simultaneous changes within both communities. Ultimately, the restored channel ‘islands’ become a continuous extension of the source area habitat. Colonization trends and time to stability are affected by number of pools, tributary streams, and elimination of rare species populations prior to reclamation.