Relationship between reproduction, sediment type, and feeding activity ofLumbriculus variegatus(Müller): Implications for sediment toxicity testing

The impact of reproduction and its interaction with sediment type on feeding activity of Lumbriculus variegatus are important because one major pathway in bioaccumulation of hydrophobic sediment-associated contaminants takes place through ingested sediment. In this study, the surface egesting behavior and the reproduction of the oligochaete were studied to understand this relationship and to give recommendations for the use of L. variegatus in sediment toxicity testing. Single individuals were used as replicates allowing proper control of reproduction behavior and egestion rate. Reproduction, growth, and egestion rates were clearly different in the two fine-grained unpolluted lake sediments used in the first 28-d experiment. The feeding of oligochaetes stopped during the reproduction process in the second 30-d experiment. Individuals divided at their middle; the anterior part took 2 d and the posterior part took 6 to 7 d to regenerate new segments and to initiate egestion. Culture conditions determined at what size the animals were able to reproduce during the test. In our tests 9 mg wet weight was the approximate minimum organism size needed for reproduction behavior. Recommendations for sediment toxicity and bioaccumulation testing using L. variegatus include using the largest oligochaetes in culture if reproduction is the endpoint and using recently fragmented individuals with complete segments if animals are employed in bioaccumulation tests.