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Research Project: Developing and Refining Technologies for Sustainable Fish Growth in Closed Containment Systems

Location: Cool and Cold Water Aquaculture Research

Title: Evaluating the microbial effects of stocking freshwater snails (Physa gyrina) in water reuse systems culturing rainbow trout (Oncorhynchus mykiss)

Author
item Davidson, John - Freshwater Institute
item Plautz, Carol Zygar - Shepherd University
item Grimm, Casey
item Jorgensen, Niels O. - University Of Copenhagen
item Podduturi, Raju - University Of Copenhagen
item Raines, Clayton - West Virginia Division Of Natural Resources
item Snader, Ryan - Maryland Department Of Environment
item Good, Christopher - Freshwater Institute
item Summerfelt, Steven - Superior Fresh

Submitted to: Journal of Applied Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/13/2018
Publication Date: 11/13/2018
Citation: Davidson, J., Plautz, C., Grimm, C.C., Jorgensen, N.G., Podduturi, R., Raines, C., Snader, R., Good, C., Summerfelt, S. 2018. Evaluating the microbial effects of stocking freshwater snails (Physa gyrina) in water reuse systems culturing rainbow trout (Oncorhynchus mykiss). Journal of Applied Aquaculture. doi: 10.1080/10454438.2018.1541771.
DOI: https://doi.org/10.1080/10454438.2018.1541771

Interpretive Summary: Microbial biofilms found in fish production systems that reuse water can be a source of pathogens and off-flavor-producing bacteria. Off-flavor continues to hamper this industry sector by creating poor consumer perception of aquatic food products, but immediate solutions have not been developed. A study was conducted to analyze the effects of native freshwater snails on biofilm, bacterial abundance, and off-flavor compounds in partial reuse systems culturing rainbow trout. General bacteria counts in water were lower in systems with snails, and the submerged surfaces of sumps with snails were nearly biofilm-free, likely due to snail grazing. Sumps without snails were coated with biofilm. Common off-flavor levels were not reduced in fish flesh, but trends for reduction were evident in trout cultured in systems with snails. This proof-of-concept study determined that there are microbial advantages associated with cohabitating snails in fish production systems that reuse water.

Technical Abstract: A study was conducted to analyze the effects of snails (Physa gyrina) on biofilm, bacterial abundance, off-flavor-producing bacteria, and off-flavor compounds in reuse aquaculture systems culturing rainbow trout (Oncorhynchus mykiss). Eight experimental-scale systems were used, including four with and without snails. Mean heterotrophic bacteria counts in water were lower (P less than 0.05) in systems with snails. Submerged surfaces of sumps containing snails were nearly biofilm-free, while sumps without snails were coated with biofilm. Geosmin levels in trout fillets from snail-stocked systems were generally lower, but not statistically different from the controls. Rainbow trout health and performance was not affected by snail presence.