Zoobenthic composition in sandy sediments of Lake Martignano (Central Italy) as a measure of quality state in the littoral.

An investigation on meio-macrobenthic invertebrates associated with littoral sandy sediments in Lake Martignano (Italy) was carried out over a period of one year. The community was composed of a low number of taxa (59), most of which belonging to nematodes and oligochaetes. The low species richness was mainly due to the absence of several invertebrates (especially insect larvae belonging to various orders, gastropods and bivalves), always present in previously studied lakes. Nematodes and in particular Theristus setosus were the largely dominant organisms. Oligochaetes reached moderate densities, followed by chironomids and copepods, and then by the remaining faunal groups, in low abundances. The measure of several indices (diversity, evenness, Naididae/Tubificidae ratio, maturity index) and the presence and abundance of bioindicator taxa (especially oligochaetes and nematodes) indicated a community typical of good environmental conditions. The obtained results support the idea that this community can play a significant role in biomonitoring, and provide further evidence of the validity of some community parameters selected for this purpose.