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

Authors: OKSANA YURIEVNA VIALOVA

Abstract: Triploid organisms, in particular oysters, are widely used in marine aquaculture. However, the advantage of triploid oysters compared to diploids has not been proven in all cases. Comparative morphological analysis of Pacific oysters Crassostrea gigas of different ploidy levels allows evaluating the benefits of raising triploids in the Black Sea. First, the morphological characteristics of diploid 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 × 10$^{-4}$ × H$_{2n}$ $^{2.56}$, R2 = 0.86 and W$_{3n}$ = 9 × 10$^{-5}$ × 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 relationship of the height and length of oyster shells was established. Significant differences in linear parameters between 2n and 3n C. gigas farmed in Donuzlav Liman are not seen. Based on these results, it is assumed that the advantage of the growth of 3n mollusks is less evident in farms located at high latitudes. The environmental factors and farm technology have probably affected the growth of oysters to a greater degree than their ploidy.

Keywords: Crassostrea gigas, triploids, allometric relationship, mariculture, Black Sea

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