Exploring the diversity and distribution of Mozambique’s soft corals (Octocorallia) through an integrative approach

Abstract

Coral reefs in the Western Indian Ocean (WIO) are experiencing continuous degradation, with projections indicating rapid disappearance due to rising sea temperatures. Mozambique has the third-largest coastline in the WIO and extensive reef areas recognized as biodiversity hotspots for tropical corals, yet many taxa remain poorly studied, especially soft corals. To address this gap, 182 colonies were collected from seven reef sites in northern and southern Mozambique using SCUBA, at depths ranging from 2.8 to 16.8 m. Species were identified using morphological and molecular phylogenetic analyses, incorporating nuclear ( 28S rDNA ) and mitochondrial ( mtMutS ) markers. A total of 63 Octocorallia species were identified along the Mozambique coast, distributed among 11 families and 23 genera, with 32 taxa unidentified at the species level. Notably, 52% of the species and 48% of the genera represent new records for Mozambique. Among these, we recorded the genus Plumigorgia for the first time in East Africa, likely representing a new species. Phylogenetic analyses revealed substantial species diversity, with many sequences not matching known records, indicating potential discoveries or the need for taxonomic revisions. Regional variations in coral communities were observed; the northern region exhibited greater diversity in growth forms, while the southern region was dominated by encrusting corals. Vamizi Island emerged as a biodiversity hotspot, hosting the highest number of families (10) and 14 genera. This study updates the soft coral fauna of Mozambique, expanding the species list from 53 to 84 and adding eleven new genera. The findings emphasize the need for continued research to support conservation and management efforts for these vital reef ecosystems.

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