BIOCHEMICAL COMPOSITION OF THREE SPECIES OF UNIONID MUSSELS AFTER EMERSION

Abstract

Freshwater mussels are emersed (exposed to air) during conservation activities such as surveys and relocations. Success of these activities depends upon the ability of mussels to survive emersion and to re-burrow in the substratum. We evaluated the acute sublethal effects of emersion on three species of unionid mussels [pocketbook, Lampsilis cardium (Rafinesque, 1820); pimpleback, Quadrula pustulosa pustulosa (I. Lea, 1831); spike, Elliptio dilatata (Rafinesque, 1820)] by measuring three biochemicals (carbohydrate, lipid, protein) indicative of biochemical function and energy storage. Mussels were acclimated in water at 25°C and exposed to five air temperatures (15, 20, 25, 35 and 45°C) for 15, 30 and 60 min. After emersion, mussels were returned to water at 25°C and observed for 14 days. Samples of mantle tissue were taken after the 14-day postexposure period and analysed for carbohydrate, lipid and protein. Three-way analysis of variance (ANOVA) did not reveal consistent trends in carbohydrate, lipid or protein concentrations due to sex of mussels, duration of emersion, air temperature or their interaction terms that indicated biological compensation to stress. Overall mean carbohydrate concentrations were greatest (range 447–615 mg/g dry wt) among the species, followed by protein (179–289 mg/g dry wt) and lipids (26.7–38.1 mg/g dry wt). These results have positive implications for conducting conservation activities, because emersion over the range of temperatures (15–35°C) and durations (15–60 min) examined did not appear acutely harmful to mussels.