Estrutura das comunidades bentônicas sésseis em recifes de arenito na Costa Oeste do Ceará, Nordeste do Brasil: variação espacial e índice relativo de pressão ambiental

Abstract

Tropical sandstone reefs are being affected by multiple human stressors and information about environmental degradation are alarming. However, knowledge about possible impacts on sandstone reefs in the tropical zone of the planet is still insufficient. The study added multiple factors of anthropogenic pressure through the relative environmental pressure index (REPI) and related to species richness, diversity of Shannon-Wiener and evenness of Pielou, furthermore the variation of the benthic community in intertidal over the west coast of Ceará was assessed. The original research was conducted in five sandstone reefs distributed on the west coast of Ceará, Northeastern Brazil (Tropical Southwestern Atlantic). The reefs are distant westbound from the city of Fortaleza. The collections of samples were carried out in the dry season in low-water spring tide. Sessile benthic communities in intertidal zone were sampled quali-quantitatively by nondestructive method - the percentage coverage of species - using the fotoquadrat. The results show greater richness and diversity in the lower areas of the reef, as well as was identified that there is a significant negative correlation (R² = 0.82, p = 0.03) between the REPI and richness of species. We observe that in areas with the highest number of human activities, we had lower number of species. The most active factors to lower biodiversity were urbanized area, the jetties to control coastal erosion, the kiosks and restaurants on the beachfront and storm sewers due clandestine sewage connections. Thus, we suggest to future work on multiple anthropogenic impacts about biological communities that aggregate indicators should be used (such as REPI) and be identified which factors have more influence on local biodiversity. The tropical zone is important, due to increased urbanization and anthropogenic pressures and is considered one of the areas of greatest marine biodiversity on the planet. The present results point to the need for better planning of infrastructure and the need for strict monitoring because the areas under greater influence of multiple human pressures are those with lower biodiversity.