The effects of suspended sediment on rainbow smelt (Osmerus mordax): a laboratory investigation

Abstract

The swimming behavior of rainbow smelt (Osmerus mordax) was evaluated at 4 concentrations of suspended sediment: 0, 10, 20, and 40 mg∙L−1 in a current gradient of 0.18–1.22 m∙s−1. Fish were significantly more active at suspended sediment concentrations equal to and greater than 10 mg∙L−1, swimming repeatedly back and forth through areas of differing current velocity. Repeated exposure of smelt to suspended sediments at 24-h intervals produced significantly more active fish only upon the third exposure. Increased swimming behavior is interpreted as an alarm response. The need for further field and laboratory research is discussed.