Application of a Benthic Euryhaline Amphipod, Corophium sp., as a Sediment Toxicity Testing Organism for Both Freshwater and Estuarine Systems
1998
Hyne, R. V | Everett, D. A
The use of an as-yet-undescribed euryhaline Corophium sp. amphipod as a sediment toxicity testing organism was assessed. The species was found to be ubiquitous in many tidal areas of the Hawkesbury River catchment. The salinity of habitat sites ranged from 0.1 to 24 ppt, sediment total organic carbon (TOC) ranged from 0.4% to 3.5%, and the fines content (< 63 μm particle size) of the sediment ranged from 4.3% to 47.6%. Monitored populations ranged from a density of 59 to 6622 individuals per m², with freshwater sites with a sediment fines content greater than 20% having the highest population densities. The sensitivity of the Corophium sp. was assessed by using copper chloride and ammonium chloride as reference toxicants in a 96-h static water-only test and a 10-day static sediment test. The LC50 for copper in freshwater-only exposures was 80 to 86 μg/L, using adult animals collected from the field. In contrast, the LC50 for copper in freshwater sediment and the sediment pore water were 840 mg/kg (dry weight) and 99 μg/L, respectively. The LC50 for ammonia (total) in freshwater-only at pH 7 was 5.5 mg/L. In contrast, the LC50 for ammonia (total) in freshwater sediment and the sediment pore water were 110 mg/kg (dry weight) and 6 mg/L, respectively. Laboratory cultures of 5‰ to 15‰ salinity were optimal for supporting the release of juveniles. Juveniles collected from laboratory cultures had a LC50 for copper in 5‰ and 10‰ salinity of 9 μg/L and 28.5 μg/L, respectively, in water-only exposures. The juveniles would be suitable for use in the development of a chronic sediment toxicity test with growth as the endpoint.
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