First record of Annella mollis (Octocorallia) from Rodrigues Island, Western Indian Ocean

Abstract

Abstract. Brihatee M, Marwyn A, Shakeel JY, Ashfaaq K, Maria RA, Homesha B, Ramkalam M, Deepeeka K, Beatriz CE, Yoshimi S, Hakim AA, Lalas JAA, Reimer JD, Wijayanti DP, Nascimento B, Ranjeet B. 2025. First record of Annella mollis (Octocorallia) from Rodrigues Island, Western Indian Ocean. Indo Pac J Ocean Life 9: 140-146. Gorgonians octocorals inhabit environments ranging from shallow tropical reefs to deep and polar waters. A habitat-forming species, they contribute significantly to habitat structural complexity and biodiversity, yet their occurrence in the Western Indian Ocean (WIO) remains poorly documented. Rodrigues Island, in particular, has lacked formal records in gorgonian species. To address this gap, ecological surveys were conducted in April 2024 at seven fore-reef sites around Rodrigues using triplicate 10×5 m belt transects surveyed by SCUBA. Results showed that only one species, Annella mollis, was recorded and was restricted to two outer reef slope sites, Tombant Coco and Ti Paté, at depths of approximately 27 m. Mean densities were low (0.17±0.01 and 0.15±0.01 individuals m⁻², respectively), and colonies were dominated by medium size classes (76-150 cm), with few larger individuals. Colonies were attached to consolidated rocky substrates on steep slopes associated with higher coral cover relative to other surveyed sites. No gorgonians were observed at the remaining five, shallower sites. These findings provide the first baseline record of gorgonians from Rodrigues Island and contribute to the limited knowledge of octocorals in the WIO. Our observations highlight the apparent restriction of A. mollis to deeper reef slope habitats around the island and underscore the need for broader surveys, temporal monitoring, and complementary morphological and genetic analyses to better understand gorgonian diversity and ecological roles in the region.