Culturing coral larvae with food supplements enhances larval size and settlement

Abstract

Maximising coral larval health is important for scaling larval production for restoration initiatives with aquaculture systems playing a vital role to support these efforts. Increasingly, research is focusing on optimising larval rearing protocols but larval feeding during ex situ culture remains under explored. Although feeding larvae can enhance settlement in Acropora species, an optimal feeding regime has not been determined. Therefore, this research aimed to quantify the effects of supplying different amounts of food on larval survival and settlement of Acropora cf. kenti larvae. During rearing, larvae were supplemented with one of three doses of homogenised Artemia (5 mL, 50 mL, or 100 mL) or an unfed control. Larval survival, larval size, settlement, and settler size were measured. There was a significant effect of feeding on settlement for medium (50 mL) and high doses (100 mL), resulting in a 2.5-fold increase in the number of settlers in these doses compared with the unfed control (17.1 ± 1.26 SE, 16.8 ± 0.78 SE, 6.9 ± 0.46 SE settlers per plug, respectively, p < 0.001). Feeding medium and high doses of food significantly increased the size of larvae (0.31mm2 ± 0.008 mm2 SE, 0.30mm2 ± 0.007 mm2 SE, respectively) compared with unfed larvae (0.26mm2 ± 0.004 mm2 SE). Feeding did not significantly affect survival which ranged from 73.3 % (±2.4 % SE) in the high food group to 82.8 % (±2.7 % SE) in the medium food group. These results demonstrate that feeding Acropora larvae during ex situ culture can increase settlement and settler size, providing a practical approach to enhance coral settler production for scaling up restoration initiatives.