Reproductive cycle of the black coral Antipathes galapagensis in the Bay of La Paz, Gulf of California, Mexico

Antipathes galapagensis, Deichmann (Smithson Misc Collect 9:1–18, 1941), has been the object of intensive fishing in the Eastern Tropical Pacific due to its large and arborescent colonies and dense forests. Despite its importance as a habitat-forming species, little information exists about its basic biology. Thus, the objective of this study is to describe its reproductive cycle. Samplings were performed in Espiritu Santo Archipelago (La Paz Bay, Gulf of California, Mexico) over 22 months. Histological analyses were conducted on 197 coral samples collected to assess their reproductive strategy from 2018 to 2019. For the first time, male and female gametogenic development stages are described for the species, determining the mean diameter and size range of oocytes and spermatocysts for each gametogenesis sub-stage. The black coral A. galapagensis is an external spawner, adopting a partial spawning strategy, showing evidence of sequential hermaphroditism, and this latter representing the first documentation for the order Antipatharia. The estimated colony sexual maturity height is 102 and 93 cm for females and males, respectively. Gametogenesis begins in June and reaches the reproductive peak in September–October, where the highest frequency is observed of mature females and males and partial spawning. The reproductive cycle shows a correlation with seawater surface temperature increase in the study area, which reaches its maximum from September–October. The results provide the first knowledge contribution to the species biology, essential for its protection and conservation management.