Unexpected patterns in the sexual reproduction of the Mediterranean scleractinian coral Cladocora caespitosa

Knowledge of reproductive biology is essential to understanding population dynamics and ecological processes in corals. Sexual condition and the reproductive cycle of the Mediterranean endemic scleractinian Cladocora caespitosa was assessed through histological analyses. Our results showed that this species is gonochoric in the Western Mediterranean Sea. Oocytes and spermaries were detected annually from March to October, reaching their maximum size between July and August coincidentally with the highest seawater temperatures. A drastic decrease in gametes between August and October indicated that spawning occurred at the end of summer. These results differ from those obtained for the Adriatic Sea, where this species was described as hermaphroditic and spawning occurred at the beginning of summer. The unusual plasticity of this temperate coral and the endangered condition of C. caespitosa bioconstructions in the Mediterranean highlight the need for further research on this topic.