Comparative morphological analysis of diploid and triploid oysters, Crassostrea gigas, farmed in the Black Sea

Abstract

Triploid organisms, in particular oysters, are widely used in marine aquaculture. However, the advantage of triploid oysterscompared to diploids has not been proven in all cases. Comparative morphological analysis of Pacific oysters Crassostrea gigas ofdifferent ploidy levels allows evaluating the benefits of raising triploids in the Black Sea. First, the morphological characteristics ofdiploid and triploid Pacific oysters C. gigas farmed in the Black Sea were studied. Allometric ratios of weight (W, g) and shell height (H,mm) of oysters were obtained, which are described by the equations $W_{2n};=;4;times;10^{–4};times;H_{2n}^{2.56},;R^2;;=;0.86$ and $W_{3n};=;9;times;10^{–5};times;H_{3n}^{2.90},;R^2;;=;0.91$. Triploids showed positive allometry and had more biomass at smaller shell height than diploid oysters. A clear linear relationshipof the height and length of oyster shells was established. Significant differences in linear parameters between 2n and 3n C. gigas farmedin Donuzlav Liman are not seen. Based on these results, it is assumed that the advantage of the growth of 3n mollusks is less evident infarms located at high latitudes. The environmental factors and farm technology have probably affected the growth of oysters to a greaterdegree than their ploidy.