Cyst-based toxicity tests. XVIII. Application of ostracodtoxkit microbiotest in a bioremediation project of oil-contaminated sediments: sensitivity comparison with Hyalella azteca solid-phase assay.

To further validate the scope of use of the 6-day sediment contact microbiotest conducted with the ostracod Heterocypris incongruens, we compared the sensitivity of this small-scale culture/maintenance-free assay with the 14-day solid-phase Hyalella azteca test. The present study was undertaken within the framework of a Canadian bioremediation project on oil-contaminated freshwater sediments along an intertidal shoreline of the Saint-Lawrence River near the town of Sainte-Croix, Quebec, Canada. Sediment subsamples, collected during three sampling periods over 21 weeks from five plots (each with four replicates) contaminated with different treatments, were analyzed for their toxic effects on the two test species.

Cyst-based toxicity tests XVI--sensitivity comparison of the solid phase Heterocypris incongruens microbiotest with the Hyalella azteca and Chironomus riparius contact assays on freshwater sediments from Peninsula Harbour (Ontario, Canada).

In view of the complexity and costs of "traditional" whole sediment assays, a "culture/maintenance free" direct contact microbiotest has been developed with the freshwater ostracod Heterocypris incongruens. The new Toxkit assay (named Ostracodtoxkit) has been applied to 33 sediment samples from Peninsula Harbour, located in Lake Superior of the Great Lakes water basin in Ontario, Canada. The microbiotest was applied in parallel to direct contact tests with the amphipod Hyalella azteca and the midge larva Chironomus riparius, to compare its relative sensitivity with that of the two "conventional" assays.