Behavioral response of Corophium volutator relative to experimental conditions, physical and chemical disturbances.

The preference/avoidance behavioral response of a widely used amphipod in toxicity tests, Corophium volutator, was investigated in relation to the presence of anthropogenic physical or chemical materials in sediments. Exposure conditions, including the density of amphipods, the depth of sediments, amount of overlying water, and exposure time, were examined for their influence on amphipods' preference for field sediments and avoidance of coarse sand. It was shown that these variables did not affect the response; thus, conditions similar to published standard toxicity tests were chosen. A gradient of sediments spiked with potential habitat disturbances that can be found on a beach or in contaminated sediments, such as those in harbors, were tested. These substances included sand, seaweed, burned wood, coal, crankcase oil, and diesel oil. To enhance the interpretation of results and decrease the variability observed when tests were conducted at different times over the summer, exposures were performed over a gradient of spike material in reference sediments. We conclude that physical obstacles added to reference sediments lead to less correlation with the behavioral response than observed with chemical interferences. Amphipods' behavior ranked harbor sediments similarly to previous studies concerning the health of intertidal mussels collected in proximity to the sediments sites. For five sites, preference of reference sediments was observed until the level of polycyclic aromatic hydrocarbons in diluted harbor sediments reached the Canadian Council of Ministers of the Environment sediment quality guidelines.