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United States Department of Agriculture

Agricultural Research Service

Title: Copper sulfate toxicity to two isolates of Ichthyophthirius multifiliis relative to alkalinity

Authors
item Straus, David
item Hossain, M - CORNELL UNIVERSITY
item Clark, T - CORNELL UNIVERSITY

Submitted to: Diseases of Aquatic Organisms
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 11, 2008
Publication Date: January 28, 2009
Citation: Straus, D.L., Hossain, M.M., Clark, T.G. 2009. Copper sulfate toxicity to two isolates of Ichthyophthirius multifiliis relative to alkalinity. Diseases of Aquatic Organisms. 81(1):31-36.

Interpretive Summary: Copper is toxic to all aquatic organisms. With fish, copper is more toxic in waters that are soft (or have a lot of rainwater in them). In this study, Ich from two different locations were tested to see if copper was equally toxic to them. We found that there is a difference between the Arkansas Ich and the Georgia Ich, with the Arkansas Ich being able to tolerate more copper. We also found that copper is more toxic in softer water, similar to what has been seen with fish.

Technical Abstract: Theronts from two different strains of Ichthyophthirius multifiliis (AR1 and G5) were exposed to copper sulfate in waters of different total alkalinities and observed for 4 h to determine relative toxicity and kinetics of parasite mortality. Consistent with the known solubility properties of the metal, copper was significantly more toxic to cells maintained under low (48 mg l-1) compared with high (243 mg l-1) total alkalinity conditions. This was reflected in both the LC50 values and rates of mortality for both parasite strains; strain differences were also observed. The AR1 strain was significantly more resistant to copper toxicity than the G5 strain in both high and low alkalinity waters. In general, these strain differences were more evident under conditions of low stress (i.e., low toxicity/high alkalinity) and suggest that genetic factors are overridden under high stress conditions. This report establishes a role for alkalinity in the effectiveness of copper sulfate treatment of Ichthyophthiriasis and reveals differences in the susceptibility of parasite populations that are clearly important for control programs.

Last Modified: 11/22/2014
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