Influence of Water Quality on Copper Toxicity to the Marsh Ramshorn Snail (Planorbella trivolvis)

Abstract

Catfish growing in aquaculture ponds can be affected by infectious diseases and environmental conditions that cause fish mortality. One problem is trematode infections. The marsh ramshorn snail, Planorbella trivolvis is the primary host of several trematodes, such as Bolbophorus damnificus, which poses a risk to channel catfish (Ictalurus punctatus). To reduce the risks and harm these trematodes cause in aquaculture, active research is sought to disrupt their life cycle by first reducing the primary host, P. trivolvis. Copper (Cu) is an effective molluscicide to treat these snails. Studies have shown that water quality, including hardness, pH, and dissolved organic carbon (DOC) greatly influences Cu toxicity. However, the influence of water quality on Cu toxicity to P. trivolvis is unknown. This study sought to fill the scientific gap to understand the influence of water quality on Cu toxicity to P. trivolvis. Specifically, this thesis research investigated the influence of pH, DOC, water hardness, and organism age on Cu toxicity to P. trivolvis. Chapter 2’s research focused on the influence of water quality on Cu toxicity to P. trivolvis, which allowed the development of multiple linear regression models describing Cu toxicity as a function of pH, DOC, and water hardness. The models can be used to calculate appropriate Cu doses for snail treatment, thereby increasing treatment efficiency, reducing treatment costs, and reducing Cu load in aquaculture pond systems. Research in Chapter 3 examined the Cu sensitivity of the snail at various life stages, which is also helpful for determining appropriate Cu doses for treating snails at specific life stages. Overall, the research has implications for snail and trematode management in catfish aquaculture.