Determining Optimum Temperature for Growth and Survival of Laboratory-Propagated Juvenile Freshwater Mussels

Abstract

The effects of temperature on growth and survival of laboratory-propagated juvenile freshwater mussels of two federally endangered species, the Cumberlandian combshell Epioblasma brevidens and oyster mussel E. capsaeformis, and one nonlisted species, the wavy-rayed lampmussel Lampsilis fasciola, were investigated to determine optimum rearing temperatures for these species in small water-recirculating aquaculture systems. Juveniles 4–5 months old were held in downweller buckets at five temperatures. Growth and survival of juveniles were evaluated at 2-week intervals for 10 sampling events. At the end of the 20-week experiment, mean growth at 20, 22, 24, 26, and 28°C was, respectively, 0.75, 2.22, 3.27, 4.23, and 4.08 mm for Cumberlandian combshell; 1.35, 3.73, 3.81, 4.90, and 4.70 mm for oyster mussel; and 2.09, 3.96, 4.99, 5.13, and 4.87 mm for wavy-rayed lampmussel juveniles. Generally, temperature was positively correlated with growth of juveniles. Final mean maximum growth occurred at 26°C for all three species, although no significant differences in growth were detected between 26°C and 28°C. The relationship between temperature and survival of juveniles was less clear. Final survival was 82.5, 89.0, 91.0, 89.5, and 93.5% for Cumberlandian combshell; 73.0, 83.5, 78.0, 78.0, and 68.1% for oyster mussel; and 75.0, 89.5, 87.0, 86.5, and 89.5% for wavy-rayed lampmussel juveniles at the five temperature treatments, respectively. Based on the species used in this study, results indicate that 26°C is the optimum temperature to maximize growth of juvenile mussels in downweller bucket systems. The ability to grow endangered juveniles to larger sizes will improve survival in captivity and upon release into the wild and will reduce time spent in hatcheries. As a result, hatcheries can increase their overall production and enhance the likelihood of success of mussel population recovery efforts by federal and state agencies, and other partners.

Received March 5, 2013; accepted July 12, 2013

ACKNOWLEDGMENTS

This project was funded by the U.S. Fish and Wildlife Service (USFWS), Asheville, North Carolina, Field Office. We thank Virginia Department of Game and Inland Fisheries’ (VDGIF) Aquatic Wildlife Conservation Center and the Freshwater Mollusk Conservation Center for providing the juvenile mussels for this study. In addition, we thank the many people who helped us complete the field and laboratory work for the project: Amanda Duncan, Mike Pinder, and Joe Ferraro, VDGIF; Gale Heffinger, USFWS; and Kasey Ewing, Tim Lane, Jennifer Rogers, Andrew Phipps, Hua Dan, Lee Stephens, Brian Parks, and Daniel Schilling, Virginia Polytechnic Institute and State University. The views expressed in this article are the authors and do not necessarily represent those of the USFWS.