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(38-48) Development and Application of Chronic and Sublethal Sediment Bioassays in the UK. Allen, Yvonne*,1, Kirby, Sonia1, Thain, John1, Reed, Jacquie1, 1 Centre for Environment, Fisheries and Aquaculture Science, Burnham Laboratory, Remembrance Avenue, Burnham-on-Crouch, Essex ABSTRACT- Many biological techniques are available to measure the acute effects of severely contaminated sediments. Research is still required to develop sublethal and chronic methods to assess the effects of moderately and lightly contaminated sediments, or those which are contaminated with persistent chemicals which do not exert acute effects e.g. PCBs. In the UK these assays can be used for monitoring purposes e.g. the National Marine Monitoring Plan and for regulatory purposes e.g. FEPA dredge material licensing scheme. Sublethal and/or full chronic whole sediment bioassays have been developed and tested using the amphipods Corophium volutator and Leptocheirus plumulosus and the polychaete Arenicola marina. Standard acute single-chemical sediment toxicity tests were performed with cadmium, phenanthrene, tributyltin and a PCB mixture (Aroclor 1260). Ten-day EC50s ranged from 11.5 to 24.5 mg/kg for cadmium, 40-51mg/kg for phenanthrene, 0.16-0.64 mg/kg for TBT and 11.7 to >688 mg/kg for Aroclor 1260. Arenicola and Leptocheirus were generally more sensitive than Corophium. Amphipod chronic tests measured survival and growth after 28 days and reproduction was also measured in the Leptocheirus tests. Chronic endpoints were generally no more sensitive than acute endpoints except in the case of Leptocheirus exposed to phenanthrene, where growth was more sensitive by a factor of two. Sublethal amphipod and polychaete (50-d) assays were conducted on moderately contaminated field collected sediments from four English estuaries. Whilst survival was not significantly affected in any of the three test species, amphipod growth and reproduction and polychaete feeding rate were significantly reduced in many of the sediments. The biological significance of these results for populations of these organisms needs further interpretation. Key words: sediment bioassay, chronic, amphipod, polychaete |
