Publication Abstract

Development and application of long-term sublethal whole sediment tests with Arenicola marina and Corophium volutator, using Ivermectin as the test compound

Development and application of long-term sublethal whole sediment tests with Arenicola marina and Corophium volutator, using Ivermectin as the test compound

Y.T. Allen, J.E. Thain, S. Haworth and J. Barry

Short-term (10-day) whole sediment tests using the amphipod Corophium volutator and the polychaete Arenicola marina are now routinely used in the UK and Europe to assess the acute toxicity of marine sediments. However, there is still a need to develop longer-term assays which measure effects on sublethal endpoints that are more relevant to predicting impacts at the population level. The effect of modifying the standard 10-day tests, by increasing exposure times and measuring additional endpoints such as growth, on the sensitivity of the assays was investigated. The test compound used was the chemotherapeutant Ivermectin (IVM), used in aquaculture to treat sea lice infestations; previous work has shown IVM to be extremely toxic to A. marina at low sediment concentrations. In this study, IVM was found to be acutely toxic to both A. marina and C. volutator, with 10-day LC50s of 18 and 22 µg IVM/kg wet sediment respectively. Casting rate (a measure of the feeding rate) of the polychaete was significantly reduced at concentrations of 4 µg IVM/kg wet sediment and above; 10-day EC50s for casting were in the region of 6 µg IVM/kg wet sediment. Extending the lugworm test to 100 days increased sensitivity, both in terms of survival and casting rate. The 100-day LC50 was 6.8 µg IVM/kg wet sediment, approximately three times lower than the 10-day LC50; the lowest observed effect concentration (LOEC) for casting was 0.5 µg 1VM/kg wet sediment, which is an order of magnitude lower than the 10-day LOEC. This assay shows potential for detecting the sublethal effects of low concentrations of sediment contaminants. Increasing the exposure time did not affect the sensitivity of C. volutator the 10-day and 28 day LC50s were similar - 22 vs 17 µg IVM/kg. A high degree of variation was associated with the growth endpoints of length and dry weight in this amphipod, therefore no conclusions could be made about the chronic effects of Ivermectin on this species.

Reference:

Y.T. Allen, J.E. Thain, S. Haworth and J. Barry (2007) Development and application of long-term sublethal whole sediment tests with Arenicola  marina and Corophium volutator, using Ivermectin as the test compound.  Environmental Pollution, 146(1): 92-99

Y.T. Allen*, J.E. Thain*, S. Haworth and J. Barry*

Environmental Pollution, 146(1): 92-99