Sediment copper bioassay for the brittlestar Amphiura elandiformis - technique development and management implications

Copper contamination is a concern in many marine and estuarine systems. In the Derwent estuary levels exceed ANZECC sediment quality guidelines in many areas. This study examined copper toxicity in the brittlestar Amphiua elandiformis with a view to relating the findings to environmental observations and ecosystem management. Knowing the concentration of copper which adversely affects brittlestars would help managers to interpret the significance of presence/absence data collected during monitoring, and to better understand ecological impacts and the current status of sediments. Species specific sediment bioassay protocols were developed to accommodate the larger than normal amounts of sediment required for brittlestar testing. Acute exposure tests undertaken in spiked and "naturally" contaminated sediments indicated a negative response (e.g. lethargy, surfacing, autotomy) at and above 165 mg Cu/kg. These findings suggest that where sediment copper concentrations exceed 270mg/kg (ANZECC high guideline value) A. elandiformis distribution may be affected.