Recolonisation of macrobenthic invertebrates in a Nigerian stream after pesticide treatment and associated disruption

Recolonisation of macrobenthic invertebrates in a tropical stream perturbed by pesticide treatment and associated human activities is discussed. The benthic community, dominated by Chironomidae, Baetidae and Naididae, was stable during the predisruption phase. The disruption severely reduced the standing crop and the diversity of macrobenthos. The recovery of the habitat was rapid. In spite of low diversity, high densities of invertebrates were recorded in the recolonisation phase. Naidids and chironomids were the most successful recolonisers while other groups recovered slowly. Most of the recolonising taxa occurred here during the pre-disruption phase and there were only a few new colonisers. The succession of recolonising taxa was distinct. The abundance of naidids and chironomids was extremely high in the initial stages of recolonisation and thereafter decreased rapidly.