Effect of temperature, hypoxia and disinfection with ozonated seawater during somitogenesis on muscular development of the trunk in larval seven-band grouper, Epinephelus septemfasciatus (Thunberg)

摘要

The cause of abnormal musculature on both sides of the same myotome in artificially cultured seven-band grouper Epinephelus septemfasciatus (Thunberg) larvae remains unclear. We evaluated the effect of three factors: changes in temperature (between 22 and 24 degrees C), disinfection with ozonated seawater (0.3mg TROsL-1, 1min), and hypoxia (22 or 14% saturation) during the early (20h post-fertilization, hpf) and mid- (24hpf) somite stages on trunk muscular development in larval seven-band grouper. The thermal regimes and disinfection with ozonated seawater had no effect on muscle development (P>0.05, G-test). In contrast, exposure to hypoxia during both the early and mid-somite stages increased the incidence of abnormal musculature in the trunk (P0.01, G-test). These larvae had abnormal musculature on both sides of the trunk. In addition, the number of abnormal myotomes differed among these larvae. Exposure in the early and mid-somite stages resulted in the highest frequency of abnormalities in the 11th and 13th myotome respectively. Our results suggest that hypoxia during somitogenesis can lead to abnormal muscle development in the trunk of artificially cultured seven-band grouper larva.