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 ...珊瑚的植食性（herbivory），尤其是共生型（symbiotic）珊瑚，至今仍存在争议。为探究石珊瑚（scleractinian coral）与软珊瑚（soft corals）捕获微藻的能力，我们开展了受控实验室实验，向珊瑚投喂5种藻类：隐藻（cryptophyte）门的Rhodomonas marina、定鞭藻（haptophyte）门的Isochrysis galbana与Phaeocystis globosa，以及硅藻（diatom）门的Conticribra weissflogii与Thalassiosira pseudonana。实验所用珊瑚物种包括：共生型（symbiotic）软珊瑚Heteroxenia fuscescens与Sinularia flexibilis、非共生型（asymbiotic）石珊瑚Tubastrea coccinea，以及共生型（symbiotic）石珊瑚Stylophora pistillata、Pavona cactus与Oculina arbuscula。我们通过终点PCR（end-point PCR）扩增从珊瑚组织基因组DNA提取物中纯化得到的藻类特异性18S核糖体RNA基因（18S rRNA gene）片段，以此评估植食行为。微藻捕获能力因珊瑚与藻类物种而异，且无法通过猎物大小或分类学地位进行解释。未在Sinularia flexibilis与Stylophora pistillata中检测到植食行为。P. globosa was ...