RELATIONSHIP BETWEEN REPRODUCTION, SEDIMENT TYPE, AND FEEDING-ACTIVITY OF LUMBRICULUS-VARIEGATUS (MULLER) - IMPLICATIONS FOR SEDIMENT TOXICITY TESTING

The impact of reproduction and its interaction with sediment type on f eeding activity of Lumbriculus variegatus ar important because one maj or pathway in bioaccumulation of hydrophobic sediment-associated conta minants takes place through ingested sediment. In this study, the surf ace egesting behavior and the reproduction of the oligochaete were stu died to understand this relationship and to give recommendations for t he use of L. variegatus in sediment toxicity testing. Single individua ls were used as replicates allowing proper control of reproduction beh avior and egestion rate. Reproduction, growth, and egestion rates were clearly different in the two fine-grained unpolluted lake sediments u sed in the first 28-d experiment: The feeding of oligochaetes stopped during the reproduction process in the second 30-d experiment. Individ uals divided at their middle; the anterior part took 2 d and the poste rior part took 6 to 7 d to regenerate new segments and to initiate ege stion. Culture conditions determined at what size the animals were abl e to reproduce during the test. In our tests 9 mg wet weight was the a pproximate minimum organism size needed for reproduction behavior. Rec ommendations for sediment toxicity and bioaccumulation testing using L . variegatus include using the largest oligochaetes in culture if repr oduction is the endpoint and using recently fragmented individuals wit h complete segments if animals are employed in bioaccumulation tests.