Sandy bottom macroinvertebrates in two moderately pollutedstations of the River Treia (Central Italy) : structural andfunctional organization

Abstract

A study on sandy bottom macroinvertebrates in two moderately polluted stations of the River Treia (Central Italy) was carried out in order to analyze their structural and functional feeding organization. A total of 60 taxa were collected during the study. Oligochaeta, Gammaridae, Diptera-Chironomidae and Ephemeroptera constituted the bulk of the total fauna. Most of the taxa were typical of sandy bottom habitats and moderate current flow. Collectors and shredders were the dominant feeding groups in both stations. Predators were strongly and positively correlated with the abundances of collectors and shredders (potential prey). Moreover, the direct relationships found between taxonomic and trophic diversities or between taxonomic and trophic evenness suggest a relatively good partitioning of food resources among the taxa. The most common organisms found in both stations were typical of mesosaprobic environments, indicating that the macrofauna of fine sediments seems to be suitable for detecting moderate organic pollution in rivers.