Comunidade bacteriana associada à água de rios e corais saudáveis e branqueados da espécie Siderastrea stellata na área de proteção ambiental Costa dos Corais - Alagoas

Abstract

Coral bleaching is seen as the result of the synergistic action of several global and local stressors, such as the presence of rivers, which, among other factors, alter the composition of the microbiota associated with corals. In order to verify the composition of the bacterial community associated with the water of the Santo Antônio and Manguaba rivers and the bacterial community associated with healthy and bleached corals at different points in the Costa dos Corais Environmental Protection Area (APACC), microarray techniques were Applied DNA and metataxonomy, as well as extensive statistical and bioinformatics analysis, such as prediction of functional groups and metagenomic content. Regarding rivers, the results indicate that a significant part of the Operational Taxonomic Units (OTUs) identified were able to survive the transition from freshwater to seawater, several of them belonging to genera involved in human pathogenesis. The BBC:A ratio and the functional prediction suggest that both rivers in the study are subject to fecal contamination and entry of xenobiotics, and that bacterial communities were more homogeneous in these environments. Regarding the corals of the species Siderastrea stellata, groups commonly associated with the bleaching process, such as Vibrionaceae and Burkholderiaceae, presented low abundance values, and the main differences between the two conditions (healthy vs. bleached) were mainly due to the enrichment of more groups. “rare” of the microbiota, but with functions already reported as important for the holobiont, in healthy individuals. The α-diversity indices indicated a similar mean of richness and diversity according to treatments and reefs, but were significantly different only temporally. The inflow of water from the Santo Antônio River seems to increase the homogeneity among the coral microbiota of the region, mainly during the rainy season, supported mainly by the β-diversity analysis and by the large number of Amplicon Sequence Variants (ASV's) belonging to the core microbiota. We suggest that the protection actions adopted for the reefs be broadly extended to the surrounding environment, as they may be affected by the input of biotic and abiotic components from activities that occur along the course of rivers, and that rarer taxa associated with corals are taken into account in these studies.