Reproduction in the Mediterranean endemic gorgonian Spinimuricea klavereni (Anthozoa, Octocorallia, Plexauridae)

Spinimuricea klavereni is a Mediterranean endemic gorgonian that is rarely encountered, probably because it typically occurs at depths below 50 m. It is exceptionally common in the northern Marmara Sea, with an unusually shallow upper depth limit of ∼20 m. The reproductive biology of this species was studied during a one year period off Büyükada, in the northeastern Marmara Sea. Spinimuricea klavereni is a gonochoric broadcast spawner with an almost even sex ratio. Colonies were ∼15 cm in height at first reproduction. Gametogenesis was continuous, characterized by high male and female fecundities year-round. Oocytes and sperm sacs of all developmental stages were found throughout the year, with small-sized oocytes and sperm sacs dominant throughout the year. The reproduction of S. klavereni did not seem to exhibit any marked seasonal pattern, unlike most other studied Mediterranean octocorals. Modest variation in gamete output was probably related to slight alterations in food availability and temperature. The non-seasonal reproductive pattern we observed may be related to the low intra-annual variation in temperature in the Marmara Sea, and the fact that the mesotrophic-eutrophic level of productivity in the Marmara Sea can support the energetic requirements of continuous gametogenesis in this gorgonian. Whether these patterns are local adaptations or intrinsic characteristics for this Mediterranean endemic species remains to be studied.