Benthic Coverage of Reef Communities in Brazilian Oceanic Islands: A Comparative Assessment
Channel: Encontro Recifal Brasileiro
Date: 2020-07-01

Ana Monteiro Leonel; Ana Cristina Monteiro-Leonel; Julia Biscaia Zamoner; Vitor Picolotto; Diana C. Vergara-Barrero; Carolina Cristina Medeiros; Tito Monteiro da Cruz Lotufo

The benthic community is an essential component of reef ecosystems and in the Southwest Atlantic these formations are dominated essentially by turf and macroalgae. Long-term monitoring helps to understand the dynamics of natural fluctuations or effects of local and global anthropic impacts. This work aims to compare a time series of benthic coverage of reef ecosystems from four groups of Brazilian oceanic islands: Rocas Atoll (RC), Fernando de Noronha Archipelago (FN), São Pedro and São Paulo Archipelago (SP) and Trindade Island (TR). These islands may be considered more pristine than coastal areas, and present distinct environmental characteristics. Shallow reefs of these islands have been sampled annually since 2013, by using photo-quadrat transects, for estimating the percentage cover of benthic organisms and by sorting them into taxonomic/functional groups according to their role in the reef ecosystem. The number of morphotypes differed widely among islands, varying from 62 in FN to 27 in SP, possibly due to factors such as size, distance from the coast (isolation) and age. Although the benthic cover was significantly different among the islands, the overall pattern showed the dominance of turf (40-50%) and macroalgae (25-50%), followed by crustose coralline algae (10-20%). In SP, Palythoa caribaeorum was also important, with an average coverage of 12.6%. Trindade was the most different, due to the greater dominance of macroalgae (47%), in relation to the turf (30%). RC and FN were the only not significantly different, corroborating a stronger connection between these islands. We concluded that Brazilian oceanic islands should be considered as distinct entities in terms of hard bottom benthic communities, except for FN and RC, that were more similar.