Hydrodynamic Effects on Growth Performance of the Pacific Oyster Crassostrea gigas Cultured in Suspension in a Temperate Bay on the Coast of Korea

The pattern of somatic growth of the Pacific oyster Crassostrea gigas cultured in suspension in Geoje-Hansan Bay, Korea was evaluated between July 2013 and March 2014 comparing culturing sites and depths. Gross biochemical composition of oyster tissues provided a measure of physiological status, and clearance rates of oysters provided a measure of feeding physiology at different water flow speeds. A growth curve model indicated greater tissue growth in the surface than in the bottom layers, and advanced summer growth by more than 4 months in the stagnant inner bay compared with winter growth in the more rapidly flowing outer bay. Our results suggest that rapid tissue growth of oysters in the surface layer in summer is supported by high primary productivity in the inner bay. In contrast, oyster growth performance at the outer bay in late fall and winter may be related to seasonal food availability that is regulated by short residence time and thereby rapid renewal of water compared to the inner bay. Furthermore, a combination of the water flow regime of the bay and the flow rate-dependent feeding physiology of oysters proved to be an important determinant of seasonal growth dynamics. Finally, oyster growth was better explained by water flow rates than by hydrographic conditions.