Effects of multiple, low-dose copper sulfate treatments on the marsh Rams-Horn Snail

Authors: MISCHKE, CHARLES - Mississippi State University; WISE, DAVID - Mississippi State University; GRIFFIN, MATT - Mississippi State University; ROSSER, T - Mississippi State University; TIWARI, AMBIKA - Mississippi State University; REHMAN, JUNAID - University Of Mississippi; ASHFAQ, MOHAMMAD - University Of Mississippi; KHAN, IKHLAS - University Of Mississippi

Submitted to: North American Journal of Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/9/2021
Publication Date: 10/20/2021
Citation: Mischke, C.C., Wise, D.J., Griffin, M.J., Rosser, T.G., Tiwari, A., Rehman, J.U., Ashfaq, M.K., Khan, I.A. 2021. Effects of multiple, low-dose copper sulfate treatments on the marsh Rams-Horn Snail. North American Journal of Aquaculture. 83:363-371. https://doi.org/10.1002/naaq.10207.
DOI: https://doi.org/10.1002/naaq.10207

Interpretive Summary: Bolbophorus damnificus has caused epizootics in catfish aquaculture since the mid-1990s. To mitigate the losses that are associated with trematode infestations, research has focused on eradicating snails from ponds. Whole-pond treatments with 0.64–1.27 mg/L Cu have been effective in killing snails; however, Cu can be toxic to fish and may result in oxygen depletions due to its algacidal properties. Given these constraints, the potential for repeated low doses of Cu as a safe, yet effective snail treatment was investigated. Adult marsh rams-horn snails Planorbella trivolvis received four weekly doses of 0, 0.10, 0.19, 0.38, and 0.76 mg/L Cu. All of the snails died after the first treatment of 0.76 mg/L Cu. The lowest doses of 0.10 and 0.19 mg/L Cu resulted in 68% and 88% cumulative mortality, respectively. This experiment was repeated with laboratory-reared adult marsh rams-horn snails in two different laboratories, resulting in 100% mortality in the 0.38 mg/L Cu treatment. A second study evaluated the effects of repeated Cu doses on egg and juvenile snail survival. Two weekly doses of 0.19 mg/L Cu were enough to kill embryos, and all of the doses =0.05 mg/L Cu prevented the snails from hatching. In a pond trial, 0.51 mg/L Cu killed 100% of the adult snails after two doses. The lowest dose of 0.13 mg/L Cu killed 60% of the snails after three doses. Repeated weekly doses <0.38 mg/L Cu may reduce adult snail populations, prevent eggs from hatching, and be safer for fish than a single dose of 0.64–1.27 mg/L Cu. These data also suggest that weekly doses <0.05 mg/L Cu may suppress marsh rams-horn snail populations by limiting hatching and impeding juvenile survival.

Technical Abstract: Bolbophorus damnificus has caused epizootics in catfish aquaculture since the mid-1990s. To mitigate the losses that are associated with trematode infestations, research has focused on eradicating snails from ponds. Whole-pond treatments with 0.64–1.27 mg/L Cu have been effective in killing snails; however, Cu can be toxic to fish and may result in oxygen depletions due to its algacidal properties. Given these constraints, the potential for repeated low doses of Cu as a safe, yet effective snail treatment was investigated. Adult marsh rams-horn snails Planorbella trivolvis received four weekly doses of 0, 0.10, 0.19, 0.38, and 0.76 mg/L Cu. All of the snails died after the first treatment of 0.76 mg/L Cu. The lowest doses of 0.10 and 0.19 mg/L Cu resulted in 68% and 88% cumulative mortality, respectively. This experiment was repeated with laboratory-reared adult marsh rams-horn snails in two different laboratories, resulting in 100% mortality in the 0.38 mg/L Cu treatment. A second study evaluated the effects of repeated Cu doses on egg and juvenile snail survival. Two weekly doses of 0.19 mg/L Cu were enough to kill embryos, and all of the doses =0.05 mg/L Cu prevented the snails from hatching. In a pond trial, 0.51 mg/L Cu killed 100% of the adult snails after two doses. The lowest dose of 0.13 mg/L Cu killed 60% of the snails after three doses. Repeated weekly doses <0.38 mg/L Cu may reduce adult snail populations, prevent eggs from hatching, and be safer for fish than a single dose of 0.64–1.27 mg/L Cu. These data also suggest that weekly doses <0.05 mg/L Cu may suppress marsh rams-horn snail populations by limiting hatching and impeding juvenile survival.