Benthic Animals

Animals (and protozoans) are highly diverse organisms in the benthos of freshwater ecosystems. Their distribution, abundance, and productivity are determined by several factors, from historical events to local abiotic and biotic conditions. Representatives of nearly every animal phylum occur in freshwaters, with aquatic insects being the most abundant and diverse benthic group. They have a large variety of morphological, physiological, reproductive, dispersal, feeding, and life history traits that have made them very successful in these ecosystems. In lakes benthic animals are found in littoral and profundal habitats, whereas in rivers and streams they are segregated by flow and velocity. Benthic metacommunities are explained by a mixture of local environmental (species sorting) and spatial (dispersal) factors, with the former being more important in freshwater ecosystems than the latter. Their responses to the environment have made them ideal organisms to assess past (e.g., paleolimnology), current (e.g., biomonitoring), and future global change effects.