Effect of microalgae and temperature on absorption efficiency of razor clam (Sinonovacula constricta Lamark, 1818)

The razor clam (Sinonovacula constricta) is a bivalve species living in the lower to mid intertidal zones along the coasts of China, Japan and Korea. In this study, the effects of temperature, microalgae species and concentration on the absorption efficiency (AE) of cultured adult SConstricta fed with six species of microalgae, including Chlorella sp., Pavlova viridis, Nitzschia closterium f. minutissima, Platymonas subcordiformis, Nannochloropsis oculata and Isochrysis zhanjiangensis was examined. The clams were exposed to three different temperatures (15, 20 and 25 degrees C) and five microalgae concentrations (0.16, 0.27, 0.37, 0.45 and 0.53mgL(-1)). The results indicated that under different temperatures, there is significant difference (P<0.05) in AE and the efficiency peaks at the water temperature of 20 degrees C. Under different microalgae concentrations, the absorption efficiencies were also significantly different (P<0.05) and there was a negative correlation between AE and microalgae concentration. At different combinations of temperature and microalgae concentration, the absorption efficiencies of Chlorella sp. and N. oculata were lower than those of other microalgae. The interaction of temperature and microalgae concentration affected the AE significantly (P<0.05).