Effects of temperature and body size on the clearance rate of a tidal flat bivalve, Coecella chinensis (Deshayes).

Abstract

There were many studies on the dependence of clearance rate on temperature and the body size of bivalves (Winter, 1973; Bayne et al., 1976; Yukihira et al., 1998). Most of these studies dealt with relatively large species, especially commercially important species. Studies with smaller but ecologically important species were relative rare (Werner and Hollibaugh, 1993). Coecella chinensis (Family Mesodesmatidae) is a small bivalve (5-30 mm in shell length) inhabiting upper tidal flats of sand-dominated sediments. We have found a dense population of C. chinensis in a tidal flat in Goeje Island. They inhabit in a relatively restricted area with a narrow band in tidal flats, which are free from contamination. Though not used for human consumption, the ecological role of C. chinensis in tidal flat community cannot be disregarded. In addition, the maintenance and conservation of uncommon species like C. chinensis are also important. This study was performed to understand the role of C. chinensis as a primary consumer in tidal flat community. As the first step, we assessed the effects of temperature and body size on the clearance rate of C. chinensis.The clearance rates (CR) of C. chinensis were highly different with different body size for each temperature. In general, CR increased as the flesh dry weight (FDW) of clam increased. CR data were fitted well to the equation CR = a(FDW)b. The exponent b value at 10℃ (0.793) was higher than those at 15 and 20℃ (0.689 and 0.685, respectively), which are similar to Glauconome chinensis (Lee et al., 2002) and Mytilus edulis (Winter, 1973). As for temperature, the range of CR was much lower at 10℃ (3.0-49.9 ml/ind./hr) than at 15℃ (7.9-84.9 ml/ind./hr) and 20℃ (6.5-80.5 ml/ind./hr). Therefore, the effect of temperature on CR of C. chinensis was greater within 10-15℃ than 15-20℃.