Application of invertebrate ecotoxicological methods to measure the effects of marine contaminants in Scottish sea lochs
Recent legislative changes have increased the need to monitor contamination effects in Scottish waters and have consequently elevated demand for research into vertebrate and invertebrate ecotoxicological techniques. Selected invertebrate ecotoxicological techniques were used to measure the effects of two industrial contaminants found in Scottish sea lochs i) the synthetic pyrethroid cypermethrin, licensed for treatment of lice infestations in the Scottish salmon farming industry and ii) polycyclic aromatic hydrocarbons (PAHs) released into Loch Leven via the Kinlochleven aluminium smelter. Mytilus edulis accumulated cypermethrin during exposure and exhibited shell closure behaviour. Neither neutral red retention (NRR) time of lysosomes nor aerial survival were affected by concentrations £1000 mg/l. As the shell closure effect occurred at concentrations greater than typical field concentrations (i.e. within and around almost sea cages), Mytilus does not demonstrate suitability for use as a study species when monitoring the biological effects of cypermethrin exposure. Carcimus maenas exhibited 50% mortality after 96 hours of exposure to the salmon treatment dose of 5 mg cypermethrin/1. Exposed crabs exhibited a tetanus-like behaviour. Sensitivity to cypermethrin was comparatively greater inCarcinus than in Mytilus . Activity of the detoxification enzyme glutathione S-transferase (GST) was assessed as a potential biomaker of exposure. GST activity was induced in crabs after 7 days of daily exposure to cypermethrin concentrations of 50 mg/l and 500 ng/l. Although GST activity was sensitive to cypertherin exposure, the brevity of the GST response reduces scope for its use as a biomarker for cypermethrin exposure in the field. Some of the techniques investigated here offer potential for further development and possible implementation into monitoring strategies for the Scottish coastal environment.