Effects of dissolved carbon dioxide on growth and vertebral column of hybrid marine grouper (Epinephelus fuscoguttatus × E. lanceolatus) early advanced larvae.

This study investigated the effects of different dissolved carbon dioxide (CO 2) concentrations (400, 700, and 1000 ppm) on the growth and vertebral column formation of hybrid tiger grouper × giant grouper (TG × GG) in their advanced larval stage under controlled laboratory conditions for 12 weeks. Growth parameters, including specific growth rate (SGR), survival rate, food consumption (FC), and food conversion rate (FCR), were calculated at the end of the experiment. Vertebral column formation was analysed using X-radiography and osteology methods. The results showed that all growth parameters were significantly affected by CO 2 concentration, with the best performances observed under 400 ppm CO2. The highest statistically significant (p < 0.05) SGR, survival rate, and FC were observed under 400 ppm CO 2 , whereas the lowest was observed under 1000 ppm CO2. The lowest FCR (0.40, p < 0.05) was observed in 400 ppm CO 2 and the highest was observed at 1000 ppm CO 2 (0.59, p < 0.05). Furthermore, larvae without vertebral column malformations were observed in 400 ppm CO 2 , while larvae with small angles of kyphosis were observed in 700 ppm CO 2 , and larvae with kyphosis, lordosis, and vertebral compression were observed in 1000 ppm CO 2. Only six spine measurements out of 31 obtained under different CO 2 concentrations were significantly different (p < 0.05). Overall, the results suggest that CO 2 concentration plays a crucial role in the growth and vertebral column formation of TG × GG in their advanced larval stage. The optimal CO 2 concentration for the aquaculture of TG × GG in their advanced larval stage was found to be 400 ppm or lower. This study highlights the importance of maintaining optimal CO 2 concentrations to enhance the growth and health of fish in aquaculture systems. • Ocean acidification harms marine hybrid larvae - tiger grouper × giant grouper (TG × GG). • 1000 ppm CO 2 results in poor growth, weight, survival, and food conversion. • Deformities in vertebral columns at 1000 ppm CO 2 ; normal at 400 ppm CO 2. • Study offers direction for further research on marine larvae in high CO 2 conditions. [ABSTRACT FROM AUTHOR]