Comparative Analysis of Growth and Survival Among Triploid Oysters from Crassostrea gigas and C. angulata Under Varying Temperature and Salinity Levels

Recently, allotriploids from Pacific oysters (Crassostrea gigas) and Fujian oysters (C. angulata) have been grown for aquaculture. However, the viability of these allotriploids remains uncertain. In this study, two autotriploids, TGG (diploid C. gigas ♀×tetraploid C. gigas ♂) and TAA (diploid C. angulata ♀×tetraploid C. angulata ♂), and two allotriploids, TGA (diploid C. gigas ♀×tetraploid C. angulata ♂) and TAG (diploid C. angulata ♀×tetraploid C. gigas ♂), were studied to assess the heterosis in growth and survival at different temperatures and salinities. The results showed that during the larval stage, TAG exhibited increased heterosis in growth and survival when temperature rose. During the adult stage, the growth of TGA significantly outperformed other triploids at higher temperatures (23 and 28 °C) and salinities (25 and 30). In contrast, TAG demonstrated the highest survival probability across all conditions except at salinity 25, where it equaled TAA after day 19. The highest oxygen consumption rates (OCR) of TGA and TAG were observed at 23 and 28  °C, while the ammonia excretion rate (AER) of TAG was significantly higher than that of TGA at 23 °C. These physiological parameters reflect the advantage of TAG in terms of survival. Notably, the temperature coefficient of allotriploids was higher than that of autotriploids in the range of 18–23 °C. At 28 °C, TAG showed the highest superoxide dismutase (SOD) and catalase (CAT) activities and the lowest malondialdehyde (MDA) content, showing its advantage when encountering high-temperature.