Habitat use of five key species of reef fish in rocky reef systems of southern Brazil: evidences of MPA effectiveness

Species functional behaviors amidst the food web, such as feeding ecology in ecosystems, are directly connected to their habitat preferences and use. In reef ecosystems, groupers and sea bass are considered key species, as top-down controllers, regulating the trophic levels on which they feed. Moreover, they are a diversified group of actinopterygian fishes, ranging from 7 to 250 cm of total length and inhabiting many types of reef habitats, from shallow waters up to 200 m deep. Due to the exceptional ecological and commercial importance of groupers and sea bass to the rocky reef systems of southwestern Atlantic and considering the small amount of information on their behavior and habitat use available for this particular region, three questions have emerged. First, how are the species spatially distributed considering the topography complexity of their environment? Second, do large Epinephelids and small Serranids have the same use of the water column, when foraging (e.g., position related to the substrate)? Third, do marine protected areas influence the distributional patterns of both families? To answer these questions, we assessed the spatial distribution and habitat use of two dominant species of groupers (Epinephelus marginatus, Mycteroperca acutirostris) and three species of sea bass (Diplectrum radiale and Serranus flaviventris and S. baldwini), using underwater visual census at Santa Catarina State, southern Brazil, during the austral summers of 2010 and 2011. All of the five sympatric species studied are directly associated with specific topographic characteristics that may be related to shelter as well as to reproduction and feeding. Except for M. acutirostris, which was mainly recorded foraging in the water column, all the remaining species are benthic dwellers. Significant evidences of effectiveness advocate that Arvoredo Marine Biological Reserve has critical importance as a refuge for heavily targeted reef species in southern Brazil, such as E. marginatus and M. acutirostris. The establishment of more protected marine areas that encompass the nursery areas near AR, along with proper enforcement, is critical to the protection of endangered and vulnerable marine species. The present work has contributed to the knowledge of habitat use and partitioning of some key reef fishes, especially target species, which is critical to effective conservation measures, including the design and management of MPAs.