Les groupements benthiques du fleuve Saint-Laurent près des centrales nucléaires de Gentilly (Québec)

Abstract

The structure and distribution of the macrobenthos were determined to evaluate the present state of the section of the St. Lawrence River which might be affected by the cooling waters of the Gentilly nuclear reactors. Ten groups were recognized, characterized by the presence of one to three constant and dominant species. In lentic conditions characterized by the presence of the gastropod Bithynia tentaculata the zonation is depth dependent. Three groups inhabit the littoral zone characterized by the Glossoscolecidae Sparganophilus tamesis. There are two groups in the sublittoral zone characterized by the Tubificidae Limnodrilus hoffmeisteri and two groups in the deep waters characterized by the Sphaeriidae Sphaerium striatinum. Bithynia tentaculata, a hydrobiid, seldom inhibits the lotic environment where the Tubificidae Limnodrilus hoffmeisteri is the only typical species.