Exploring benthic and ichthyofaunal diversity of black coral forests in Santo Antão, Cabo Verde

Mesophotic black coral forests (BCFs) are vital marine ecosystems that support diverse biological communities. Despite their ecological significance, BCFs remain understudied, particularly within the tropical Atlantic realm. The Cabo Verde archipelago, recognised as a marine biodiversity hotspot, offers a unique setting for exploration. This study presents the first assessment of benthic and ichthyofaunal diversity associated with BCFs along the coast of Santo Antão Island, characterising community structure and spatial variability. BCFs were dominated by 3 species: Antipathella wollastoni , Stichopathes luetkeni , and Tanacetipathes spinescens . Surveys were carried out at 8 locations, ranging from 30 to 68.7 m depth. Image analyses revealed 42 benthic taxa and 52 confirmed fish species across all sites, with considerable spatial variation in community composition. Hanging Garden exhibited the highest benthic taxon richness (25 taxa) and Shannon-Wiener diversity ( H ’ = 2.12), while Janela showed the greatest ichthyofaunal richness and diversity (20.5 taxa, H ’ = 1.83). Benthic communities were characterised by high coverage of rhodoliths, other red algae, and encrusting sponges, while the endemic damselfish Chromis lubbocki was the dominant fish species across all sites. Diversity indices and rarefaction analyses indicated varying levels of community complexity, suggesting the influence of local environmental conditions and habitat characteristics. This study provides the first comprehensive baseline of BCF-associated biodiversity in Cabo Verde, emphasising their importance for marine conservation. The findings highlight the need for targeted conservation strategies to safeguard these vulnerable ecosystems.