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Influence of diet on survival, growth, and physiological condition of fingernail clams Musculium transversum

Naimo, T. J., Cope, W. G., Monroe, E. M., Farris, J. L., and Milam, C. D., 2000, Influence of diet on survival, growth, and physiological condition of fingernail clams Musculium transversum: Journal of Shellfish Research, v. 19, no. 1, p. 23-28.

Abstract

The effects of diet and laboratory holding time on survival, growth, and physiological condition of fingernail clams Musculium transversum were evaluated in a 112-day study. The diets included a commercial oyster diet, a suspension of commercial rabbit pellets, a suspension of fine, organic-rich sediment, and a complete sediment renewal every 14 days. Sediment and clams were obtained from a relatively uncontaminated site in the Upper Mississippi River. The experimental design consisted of 18 370-mL beakers per diet, each containing 5 cm of surficial sediment and 15 clams. Survival of clams was measured daily in each unit. Three units from each diet were randomly removed on days 7,14,21,28,56, and 112, and clams were measured for shell length. Glycogen and cellulase activity were measured in composite samples (5 clams per sample) at each of the six time intervals. Cellulase activity did not vary among diets or with time. Survival, growth, and glycogen varied significantly among diets, and glycogen concentrations varied with time, regardless of diet. Clams exposed to the two sediment diets were 2.4 times more likely to survive than clams exposed to the commercial diets. Survival of clams in all diets exceeded 80% through day 21. Although clams maintained an acceptable survival rate for 21 days, their physiological condition was compromised much earlier, given that glycogen reserves were reduced by 14-54% after only 7 days. Thus, laboratory tests with fingernail clams should include physiological measures, in addition to survival, to ensure that clams are in suitable condition before and during testing.

Keywords

Diet, Musculium transversum, survival, growth, biomarker