Active biomonitoring using the freshwater crustacean Gammarus fossarum: an operational tool to monitor chemical contamination and toxicity in continental surface waterbodies

The degree of pollution of waterbodies is traditionally appraised by micropollutants research and quantification applied in sediment or in water. While this chemical approach can determine contamination of the targeted compounds in waterbodies, it is inadequate for assessing the bioavailability of chemical substances and toxic impact of aquatic environments (characterized by complex mixture of pollutants) which are currently proposed as complementary analysis. Because of the need of such diagnosis tools for public and private managers, substantial efforts have been made over the last 30 years to develop and apply innovating biological approaches for risk assessment. In this context, this presentation focuses on using a crustacean model, the freshwater amphipod Gammarus fossarum, to assess chemical contamination and toxicity. Our approach of active biomonitoring, based on calibration of “control” individuals (size, sex, population,…) which were exposed during 7 days directly in waterbodies (by caging methodology), is an integrative and relevant approach for field experiments. To demonstrate it, we will show how in situ bioassays bring complementary information to public and private managers in illustrating by various cases of study: waste water treatment plant, storm pillway, dam draining as well as industrial sites. During these field experiments, we finally assessed 1- level of bioavailability contamination for metallic and organic compounds in exposed gammarids and 2- ecotoxicological effects on global parameters (survival, feeding rate, reprotoxicity) and on specific parameters (acetylcholinesterase activity, endocrine disruption). For a reliable data interpretation, we proposed threshold values for bioaccumulated concentrations and biological responses. The general purpose is to highlight the operational, cost-effective and reliable character of active monitoring using gammarids for a large scale deployment in waterbodies.