The dynamics of the density and distribution of larvae of the Pacific oyster Crassostrea gigas (Thunberg, 1793) in the Amursky and Ussuriisky bays of the Sea of Japan

The terms of the occurrence in the plankton of the pelagic larvae of the Pacific oyster Crassostrea gigas in the Amursky and Ussuriisky bays, along with their abundance and distribution, were studied in 2007 and 2008. The larvae occurred in the plankton from May to September at a water temperature of 13–23°C. In both bays, their larval density was the highest in July, the period that precedes the maximum water temperature; in August it decreased by 2 times. The average density of the oyster larvae in the Amursky Bay was 475 ind./m 3 in 2007 and 400 ind./m 3 in 2008, in the Ussuriisky Bay it was 275.0 and 7.5 ind./m 3 , respectively. The distribution and abundance of C. gigas larvae in the surveyed bays are in good agreement with the published data on the quantitative distribution of adult mollusks. The results are discussed in relation to the hydrology and the physical and chemical parameters of the bays.