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 µg Cu l . 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.

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The aim of this study was to assess the suitability of Gammarus duebeni as an indicator of estuarine pollution. This involved the development of sub-lethal pollution bioassays monitoring respiration rate, swimming efficiency and precopula pairing; assessment of the sensitivity of the assays to copper pollution and comparison of the suitability of the assays. Significant impairment of respiration rate, as measured by changes in pleopod beat, was determined at a copper concentration of 600 μg 1−1. Significant impairment to swimming ability was determined after exposure to copper pollution at a concentration of 600 μg 1−1 and precopula pairing was significantly reduced at a concentration of 600 μg 1−1. Of the assays, swimming efficiency and pleopod beat frequency appear to offer the most potential for further development. The lower limit of sensitivity of the bioassays developed in this study is yet to be determined. However, the levels of copper shown to induce an effect can be experienced in the natural environment. The study has shown thatGammarus duebeni can be used in sub-lethal pollution assays, at relatively high Cu concentrations, and indicates that it is potentially a useful species with which to assess estuarine water and sediment pollution.

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