LIFE-HISTORY CHARACTERISTICS OF THE FRESH-WATER OSTRACOD CYPRINOTUS INCONGRUENS AND THEIR APPLICATION TO TOXICITY TESTING

The biology of ostracod crustaceans suggests that this group could be a useful model for sediment toxicity testing. We examined life history characteristics of the freshwater ostracod Cyprinotus incongruens in the laboratory (25 degrees C), then used length after 10 days as a res ponse variable in a sediment toxicity test. Life history results indic ated that both fecundity (0-64 total eggs per female), and egg develop ment time (1->157 days), were highly variable. In contrast, juvenile d evelopment time showed less variation (7-16 days), and thus body lengt h after 10 days was chosen as a sublethal bioassay character. A bioass ay experiment using sediments isolated from mine-impacted cobble strea ms indicated that C. incongruens had a higher sensitivity to variation in sediment quality than the cladoceran Ceriodaphnia dubia. Surprisin gly, the results indicated no correspondence between concentration of metals and toxicity in either C, incongruens or C. dubia. Overall our results indicate that ostracods are a good candidate taxon for subleth al toxicity tests of contaminated sediments.