Ecologia e Fisiologia - Pôsteres - 28/11/2023 - 15:30 h às 16:30 h

Coral reefs shelter the highest marine biodiversity on the Earth. Such diversity extends to mesophotic ecosystems (30–150m), but the filters that drive the distribution and functional attributes along depth gradients are still unknown. The Tropical Atlantic Province have several mesophotic ecosystems that support many endemic species. Here, we sought to respond to how the interactive biogeographic effects and environmental filters shape the vertical fish diversity patterns in ME, in order to understand how the functional attributes lead to fish assemblage distribution in different depth zones. The study sites include Fernando de Noronha Archipelago (FNA) and Saint Peter & Saint Paul Archipelago (SPSPA), Brazil, in the Atlantic. These areas are internationally recognized as an environment of high economic and ecological value, having marine protected areas limited to shallow reefs. This characteristic suggests the importance of management policies for deep reefs, since they are affected by fishing exploitation and pollution.  We characterized the fish community using underwater visual census using mixed-gas closed-circuit rebreathers at depths down to 120 m. We registered 6.982 individuals distributed in 45 families and 95 species and classified the assemblages according to the depth zone: shallow and mesophotic. Our results show that species richness was higher in shallow communities in the largest and least isolated island, following the expected according to the island biogeography theory. However, we found opposite results for functional richness, where the highest values were found in the smallest and most isolated island. Therefore, our results indicate that biogeographic filters affect species and functional richness in different ways, and also that shallow and mesophotic seems to be structured by distinct rules. Like shallow reefs, mesophotic should also be included in environmental protection plans, giving attention to the unique ichthyofauna found at these depths.