Coral feeding on microalgae assessed with molecular trophic markers

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 Rhodomonas marina, the haptophytes Isochrysis galbana and Phaeocystis globosa, and the diatoms Conticribra weissflogii and Thalassiosira pseudonana. Coral species included the symbiotic soft corals Heteroxenia fuscescens and Sinularia flexibilis, the asymbiotic scleractinian coral Tubastrea coccinea, and the symbiotic scleractinian corals Stylophora pistillata, Pavona cactus and Oculina arbuscula. Herbivory was assessed by end-point PCR amplification of algae-specific 18S rRNA 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 ...