The effects of copper (Cu), pentachlorophenol (PCP) and benzo[a]pyrene (B[a]P) on swimming efficiency and embryogenesis of Chaetogammarus marinus were examined. Swimming stamina against a pump driven head flow of water was significantly impaired at concentrations of 15 mug Cu 1(-1), 40 mug PCP 1(-1) and 20 mug B[a]P 1(-1). Development of in vitro cultured embryos was significantly impaired by 20 mug Cu 1(-1), 20 mug PCP 1(-1) and 20 mug B[a]P 1(-1). Cu and PCP extended the period of embryogenesis by 4 to 8 d while embryos cultured with B[a]P hatched at the same time as controls but were significantly smaller. Specific stages in the embryos' development were affected by each pollutant. Stage 1 was resistant to these effects but Stages 2 to 4, in which the embryo undergoes development of the germinal disc, dorsal organ rudiments, cordal furrows appendage rudiments and segments, eye and heart, were all prolonged in toxicant-exposed treatments. The time taken for Stage 5 of embryogenesis was generally reduced in pollutant exposed embryos. The results indicate that both swimming stamina and embryogenesis in C, marinus may be used as sensitive bioassays for toxic effects in estuarine areas. In the case of Cu, the assays are responsive at environmental concentrations periodically experienced at some locations on the Humber estuary, United Kingdom. The swimming stamina assay has the advantage that it reflects the competence of the animals over a range of integrated physiological processes while the embryo assay has the advantage that effects at this level may reflect population level responses to pollution.
