ARS | Publication request: Effects of water chemistry on the toxicity of Cu to the fish parasite Ichthyophthirius multifiliis: Development of a BLM for therapeutic application

Submitted to: Society of Environmental Toxicology and Chemistry Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: September 20, 2011
Publication Date: November 13, 2011
Citation: Ryan, A., Straus, D.L., Tomasso, J. 2011. Effects of water chemistry on the toxicity of Cu to the fish parasite Ichthyophthirius multifiliis: Development of a BLM for therapeutic application [abstract]. Society of Environmental Toxicology and Chemistry North America 32nd Annual Meeting, Navigating Environmental Challanges: Historical Lessons Guiding Future Directions, November 13-17, 2011, Boston, Massachusetts. p.391.

Technical Abstract: Ichthyophthirius multifiliis (Ich) is a common ectoparasite that invades the skin and gills of freshwater fish. Copper sulfate (CuSO4) is often used to control infestations of Ich in pond aquaculture in the United States. In this study, we determined the acute toxicity of CuSO4 to the free-swimming theronts of Ich in reconstituted waters. Water chemistry characteristics, including calcium, magnesium, and pH were varied independently and spanned relevant ranges. The objective of these experiments was to provide data that would serve as the basis for development of a biotic ligand model (BLM) that could be used to derive therapeutic doses of copper sulfate in aquaculture operations. A BLM for such purposes would be ideal because it could define effective bioavailability-based doses for controlling Ich outbreaks while simultaneously evaluating if copper doses would be safe for fish. Preliminary data analysis suggested that solution chemistry influenced the toxicity of CuSO4 to Ich, and that Ich strain or batch contributed to the variability in the observed effect concentrations. Development of a BLM for Ich may have to be strain-specific, which for aquaculture purposes suggests that the least sensitive Ich strain should be used for BLM development.