Short-term recolonization of stones in a tropical island stream

The recolonization of stones by macroinvertebrates in streams can occur at very small temporal scales, an often-neglected factor in recolonization studies. In a tropical stream in Coiba National Park, Panama, 36 stones were washed and brushed and each one was subjected to four different periods of exposure in a riffle (1, 3, 9, 27 h). Ephemeroptera, together with Diptera, Trichoptera, Coleoptera, Lepidoptera and Hydracarina, were the main recolonizers. Total density of individuals, and density and relative abundance of the most common taxon (Baetidae : Ephemeroptera), showed significant variation over the four recolonization periods, partially explained by some abiotic variables (water depth, current velocity and stone shape). Taxa richness, community evenness and taxonomic composition did not vary significantly over the four periods. The recolonization of stones in the tropical stream began immediately after the disturbance, although only some community characteristics varied significantly over the first hours.