Handling effects on survival and growth of plain pocketbook Lampsilis cardium (Rafinesque, 1820) freshwater mussels

Abstract

Handling freshwater mussels may have negative impacts on their survival, growth, or reproduction, and this may affect our interpretation of how mussels respond to research and conservation actions. The goal of this study was to investigate how repeated dislodgement and emersion during handling affects survival and growth of plain pocketbook Lampsilis cardium. Sixty mussels were exposed to one of the four handling rates: (1) control (no handling), (2) handled every other week, (3) handled once per week, or (4) handled twice per week, during an 85-day laboratory experiment in 2017. Absolute daily growth rates were compared among control and treatment group mussels. Growth rates were positive for > 98% of mussels and no mortality occurred. A likelihood ratio test indicated that growth rates did not differ among treatment groups (χ2 (3) = 1.32, P = 0.72). The best growth rate model was an intercept-only model which predicted that an average mussel grew 0.0088 mm/day (95% confidence interval 0.0070–0.0106). Our results suggest that L. cardium survival and growth is not compromised by short-term, repeated handling as often as twice per week, but consideration of handling procedures and mussel characteristics is necessary to fully understand how handling may affect other mussels.