Optimizing heterotrophic feeding rates of three commercially important scleractinian corals

Heterotrophy plays an important role in improving coral growth rate in aquaculture. While a lack of sufficient food will reduce growth and delay production timelines, excessive food deteriorates water quality and represents an additional production cost without benefit. Currently, there is limited information about the maximum feeding rates of corals. Using the curvilinear Michaelis-Menten model with six different concentrations of Artemia during day and night feeding, we estimated the maximum feeding rates for Acropora millepora (4.6 ind cm(-2) h(-1)), Hydnophora rigida (20.4 ind cm(-2) h(-1)) and Duncanopsammia axifuga (22.8 ind polyp(-1) h(-1)) and the necessary concentrations of food to reach the maximum levels of feeding. Overall, the three species increased their feeding rates with increasing Artemia densities until the concentration reached 120 ind ml(-1), after which there was no change to feeding rate. No significant differences were detected between day and night feeding rates for the three corals species. We demonstrate that the concentration to reach the maximum Artemia feeding rates for these commercially important coral species was above 50 ind ml(-1).