Reef fish and benthic community structures of the Santa Luzia Marine Reserve in the Cabo Verde islands, eastern central Atlantic Ocean

Abstract

Understanding ecological structures and the dynamics of reef fish assemblages is a fundamental step in current conservation biology. Patterns of abundance and biomass of reef fish communities of the tropical Cabo Verde Archipelago (eastern central Atlantic Ocean) have not been assessed previously. We studied general patterns of reef fish trophic groups and benthic cover at 11 sites around Santa Luzia Island, employing underwater visual census (UVC) and benthic photo-quadrats. Fish assemblage attributes were plotted against several descriptors, such as fishing intensity, water surge, and complexity and type of substrate, using multivariate analysis. The 15 most abundant species accounted for 94.12% of all fishes censused by UVC; nine of these were also among the 15 species with the highest biomass. The families Muraenidae, Pomacentridae and Labridae were the most speciose, while Chromis spp. (Pomacentridae) and Labridae were the dominant groups in terms of both density and biomass. In terms of trophic groups of fishes, planktivores dominated fish density (69%, with 4 species), followed by mobile invertebrate feeders (17.9%, with 13 species), with other groups such as carnivores (3.6%) and roving herbivores (2.7%) being less prevalent. The benthic community was partially dominated by crustose coralline algae and macroalgae (more than 25% of total coverage). The low densities of large piscivorous and carnivorous fishes in the reserve might be directly linked to overfishing. The highest fish and benthic biodiversity were detected in the northwestern Santa Luzia reef sites, indicating this area as a priority for establishment of a no-take zone in the future.

Keywords: biodiversity, conservation, oceanic MPA, overfishing, trophic groups, underwater visual census, West Africa