Environmental factors affecting the distribution of Spongilla lacustris (Linnaeus, 1759 - Porifera, Spongillidae) in an artificial canal in northwestern Italy

Abstract

The hydrographic network of the upper Po Valley is characterized by the presence of numerous hydroelectric plants, often powered through the use of artificial canals. These canals, which range from a few hundred meters to several kilometers, are used to convey water from the rivers to the electricity production plant. Power canals are usually characterized by concrete banks and bottoms, a geometric profile, and the absence of riparian vegetation so that they host peculiar invertebrate communities, often extremely adapted to life in a completely artificial habitat. Sponges are an often little considered component of the freshwater macroinvertebrate fauna, whose functions and role within communities can be of considerable interest. These organisms can colonize artificial canals, but little is known about local environmental characteristics can influence their distribution. In this study, we investigated the distribution of a freshwater sponge, Spongilla lacustris (Linnaeus, 1759), in a 4.5 km long artificial channel in Rocca Grimalda (Alessandria), NW Italy. A total of 863 specimens were localized and measured, and selected environmental characteristics were recorded. We observed that the distribution of sponges depends mainly by the lighting rather than the type of substrate or other local factors, so that this species is well-suited to colonizing artificial environments with good water quality conditions.