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Abstract :
[en] The structural complexity of shallow tropical reefs comes mainly from hermatypic corals (Scleractinians). However, in certain areas of the world, ahermatypic coral species, such as Antipatharians, also known as black corals, can thrive. These black corals create complex structures that can serve as habitats for many marine species. These corals are generally found at great depths (> 50 meters), which makes it difficult to study and explains the lack of knowledge about this system. However, when certain conditions are met, Antipatharians can colonize shallow reefs (15-30 meters) offering an opportunity to study their ecological roles. In the Gulf of California (GC), a hypothesis dating back to the mid-2000s suggests that shallow black coral forests could serve as habitats or nurseries for several fish species, in particular serranids, some of which are endangered on the IUCN Red List. Studying this ecosystem is, therefore, essential to understand how Antipatharians shape reef fish diversity and will help to reveal the importance of this system for biodiversity conservation. Here, we studied the ichthyological diversity in terms of density, biomass and assemblage composition within black coral forest, black coral patches and rocky reefs in Bahia de Los Angeles in the GC using visual transects. We found higher density and richness, as well as a distinct assemblage composition in black coral forest in comparison to the other two habitats. The spotted sand bass (Paralabrax maculatofasciatus) was exclusively found in black coral forest at a higher density than that observed in other historical data on this species in the GC. Two other species (Paralabrax auroguttatus and Oxycirrhithes typus) were only found within black coral branches. Our findings reveal the importance of black coral forests for highly targeted species and call for future large-scale studies on this ecosystem in the northern part of the GC.
