Effects of metals on feeding rate and digestive enzymes in Gammarus fossarum: an in situ experiment.

The feeding activity and afterward the assimilation of the products resulting of the food digestion, allow organisms to obtain energy useful for growth, maintenance and reproduction. These biological parameters may be studied to assess the impact of contaminants on the energy metabolism of organisms, which could induce potential effects at an individual level. The studied species was an amphipod Gammarus fossarum, which has a high ecological relevance since it is widespread in European streams and plays a major role in the breakdown of leaf litter. Thus some G. fossarum were transplanted in four sites of a river characterized by metal contamination (Amous River, France). The following parameters were studied: digestive enzymes activities (esterase, beta-glucosidase, beta-galactosidase, amylase and endoglucanase), feeding rate, metal bioaccumulation and survival. Results showed a strong relationship between digestive enzymes activities, feeding rate and metal contents.