Coral feeding on microalgae assessed with molecular trophic markers

Abstract

Herbivory in corals, especially for symbiotic species, remains controversial. To investigate the capacity of scleractinian and soft corals to capture microalgae, we conducted controlled laboratory experiments offering five algal species: the cryptophyte R hodomonas marina , the haptophytes Isochrysis galbana and P haeocystis globosa , and the diatoms C onticribra weissflogii and T halassiosira pseudonana . Coral species included the symbiotic soft corals H eteroxenia fuscescens and S inularia flexibilis , the asymbiotic scleractinian coral T ubastrea coccinea , and the symbiotic scleractinian corals S tylophora pistillata, P avona cactus and O culina arbuscula . Herbivory was assessed by end‐point PCR amplification of algae‐specific 18 S r RNA gene fragments purified from coral tissue genomic DNA extracts. The ability to capture microalgae varied with coral and algal species and could not be explained by prey size or taxonomy. Herbivory was not detected in S . flexibilis and S . pistillata . P . globosa was the only algal prey that was never captured by any coral. Although predation defence mechanisms have been shown for P haeocystis spp. against many potential predators, this study is the first to suggest this for corals. This study provides new insights into herbivory in symbiotic corals and suggests that corals may be selective herbivorous feeders.

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