Microbial perspective on the giant carbonate ridge Alpha Crucis (Southwestern Atlantic upper slope)

Abstract

Deep-sea carbonate mounds can harbor a wide variety of heterotrophic and chemosynthetic microbial communities, providing biodiversity hotspots among the deep-sea benthic ecosystems. This study examined the bacterial and archaeal diversity and community structure in the water column and sediments associated to a recently described giant carbonate mound named Alpha Crucis Carbonate Ridge (ACCR), Southwestern Atlantic. Due to the acoustic evidence of gas chimneys from a previous study, we further evaluated the chemosynthetic primary production through in situ-simulated dark carbon fixation rates. Pelagic microbial communities varied significantly with depth, showing a high abundance of photosynthetic groups in surface waters and taxa related to nitrification in intermediate and deep waters. The benthic communities from the top of the ACCR were very similar along with the sediment depth, while those from the base of ACCR showed a clear stratification pattern, with members in the deep strata mainly related to anoxic and chemosynthetic ecosystems. Dark carbon fixation rates were of the same order of magnitude as those of deep-sea cold seeps and hydrothermal vents. Our study provides the first description of the ACCR microbiome and adds new information to help formulate and implement future conservation and management strategies for vulnerable marine ecosystems.

Diversidade e Estrutura de Comunidades Microbianas em Áreas de Pockmarks e Diápiros de Sal na Margem Continental Brasileira (Sudoeste do Oceano Atlântico)

“…By contrast, 27% of the community variability (p<0.001) was explained by the vertical sediment strata -surface (0-2 cm) versus subsurface (16-18 cm or 22-24 cm). This finding is in agreement with previous studies showing remarkable differences in prokaryotic communities along the sediment strata, which is attributed to the sharp changes in physical and chemical conditions with depth [17,59,75,76]. Another interesting pattern was revealed by NMDS ordination, where all surface sediment communities were concentrated in a tight cluster, indicating high similarity in their composition, while lower similarity was observed among subsurface samples (Fig.…”

“…In recent decades, there has been greater access to genomic techniques, which has led to an increase in studies aimed at understanding microbial communities in marine sediments (FRASER et al, 2018;BENDIA et al, 2021;BRUCE et al, 2022).…”

“…Although the majority of pockmarks in this area are thought to be not actively seeping gas, acoustic data and metal proxies have suggested the presence of recent to sub-recent seepage activities in some of the pockmarks [9,[13][14][15][16]. In addition, the unique characteristics of the seafloor in this area may provide a myriad of habitats for diverse but yet poorly explored microbial communities [17].…”

Methane-related community of a carbonate-enriched pockmark, Brazilian Southeastern continental slope

“…Analyses were developed as detailed in Bendia et al (2021). Raw sequences were imported to QIIME2 (v.2020.2, https://docs.qiime2.org/) (Bolyen et al, 2019) using the q2-tools-import script.…”

Sedimentation in the adjacencies of a southwestern Atlantic giant carbonate ridge

“…These features are unique and very vulnerable dominated by framework-building cold-water corals, and their growth reflects the characteristics of the surrounding environment and ocean currents systems (van Weering et al, 2003;Eisele et al, 2008;Steinmann et al, 2020). Deep-sea carbonate mounds are Santos et al important not only to coral species but also to the rich and diverse habitat created in these environments (Le Guilloux et al, 2009;D'Onghia et al, 2012;Morigi et al, 2012;Fentimen et al, 2018;Bendia et al, 2021).…”