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(70-55) Development of bioassays with marine amphipods from the Sydney region for assessing metal contaminated sediments. Hyne, Ross1, Gale, Sharyn*,2, King, Catherine3, Simpson, Stuart3, 1 NSW Environment Protection Authority, c/- UTS, PO Box 123, Broadway, NSW2 University of Technology, Sydney. PO Box 123, Broadway, NSW3 CSIRO. PMB 1, Menai, NSW ABSTRACT- The use of current marine sediment bioassays in Australia are limited for many reasons, in particular low sensitivity and lack of abundance of test species. This study aimed to compare the sensitivity of four sediment-dwelling amphipods, from estuaries in the Sydney region, to heavy metal contaminated sediments. Procedures for culturing the most sensitive species in the laboratory were then developed. The species tested have varying feeding strategies and habitat preferences, and thus different metal exposure routes. Grandidierella japonica, Grandidierella gilesi and Corophium cf volutator are infaunal filter feeding species, whereas Melita plumulosa is an epibenthic deposit feeder. Species sensitivity was initially screened using a 10-d static sediment test with sediment spiked with either copper (1300 mg/kg) or zinc (4000 mg/kg) to give metal concentrations approximately 20 times their respective sediment quality guideline values. Sufficient equilibration time was allowed to ensure that porewater metal concentrations were low. M. plumulosa was significantly (P<0.05) more sensitive to both copper and zinc spiked sediments compared to the selective feeding species. Sensitivity of M. plumulosa to cadmium, copper, lead and zinc was then determined using 10-d static sediment and 96-h water-only tests. M. plumulosa was successfully cultured in the laboratory. Maximum reproduction and survival rates of cultures were achieved by optimising feeding and environmental parameters such as temperature, salinity and grain size. Mature M. plumulosa females produced an average of 10 offspring per fortnight and offspring matured after 7 weeks. These findings will be used to develop a new marine sediment bioassay, for use in assessing the bioavailability of metals in contaminated sediments. Key words: sediment, heavy-metals, amphipods, marine |
