Biodiversity patterns along a salinity gradient: The case of net-spinning caddisflies

Abstract

Many studies have shown that salinity reduces diversity and abundance of, and alters trophic structures in freshwater macroinvertebrate communities. However, the role of salinity in interactions among coexisting species is poorly documented. We investigated the faunal response of net-spinning caddisfly larvae to a salinity gradient (ranging from 0.21±0.02 to 2.60±0.46 g • l-1), using common descriptors such as species richness and diversity, but also innovative tools such as bio/ecological trait combinations. Net-spinning caddis larvae were sampled each month in 2002 at four sites, differing only in salinity level, located on the Meurthe River (France). A total of 11 different net-spinning caddisflies species, representing eight different genera, were sampled in 2002. The highest taxonomic diversity and equitability were observed for an intermediate salinity level. The study of the distribution of bio/ecological traits of species corroborates this observation and we postulate that results are in accordance with the Intermediate Disturbance Hypothesis. © Springer 2005.