Scleractinian corals rely on heterotrophy in highly turbid environments

Coral communities can survive in stressful environments; however, the mechanisms corals employ to endure challenging conditions are poorly understood. This study assessed how the heterotrophy of three coral genera (Acropora spp., Porites spp. and Platygyra spp.) varies among sites in the Dampier Archipelago, Western Australia, exposed to different levels of turbidity. Stable isotope δ ¹³C and δ ¹⁵N analysis of coral host and endosymbionts were combined with modern Bayesian isotopic niche analysis to demonstrate that heterotrophy in all three coral genera increased in highly turbid environments. While all coral genera were found to be more heterotrophic in highly turbid waters, Porites spp. favoured heterotrophy across all levels of turbidity, whereas Platygyra spp. and Acropora spp. were less heterotrophic at sites with lower turbidity. Thus, some scleractinian corals can alter their feeding strategies in response to turbidity levels. As nearshore coral reefs experience increased and prolonged turbidity with intensifying climate change and anthropogenic development, the knowledge gained from this study will allow for improved environmental impact assessment and predictive modelling for future coral reef conservation.