Microbiota associated with tubes of Escarpia sp. from cold seeps in the southwestern Atlantic Ocean constitutes a community distinct from that of surrounding marine sediment and water

Abstract

As the depth increases and the light fades in oceanic cold seeps, a variety of chemosynthetic-based benthic communities arise. Previous assessments reported polychaete annelids belonging to the family Siboglinidae as part of the fauna at cold seeps, with the 'Vestimentifera' clade containing specialists that depend on microbial chemosynthetic endosymbionts for nutrition. Little information exists concerning the microbiota of the external portion of the vestimentiferan trunk wall. We employed 16S rDNA-based metabarcoding to describe the external microbiota of the chitin tubes from the vestimentiferan Escarpia collected from a chemosynthetic community in a cold seep area at the southwestern Atlantic Ocean. The most abundant operational taxonomic unit (OTU) belonged to the family Pirellulaceae (phylum Planctomycetes), and the second most abundant OTU belonged to the order Methylococcales (phylum Proteobacteria), composing an average of 21.1 and 15.4% of the total reads on tubes, respectively. These frequencies contrasted with those from the surrounding environment (sediment and water), where they represent no more than 0.1% of the total reads each. Moreover, some taxa with lower abundances were detected only in Escarpia tube walls. These data constitute on the first report of an epibiont microbial community found in close association with external surface of a cold-seep metazoan, Escarpia sp., from a chemosynthetic community in the southwestern Atlantic Ocean.

Gas Seeps at the Edge of the Gas Hydrate Stability Zone on Brazil’s Continental Margin

“…The feather edge of the MHSZ is estimated within a range of depths, between 510-760 mbsl on the Rio Grande Cone and 500-670 mbsl on the Amazon deep-sea fan. Comparison of these depth ranges with recently published observations based on water column, seafloor and sub-bottom acoustic imagery and samples from piston cores [46,47,52] indicates that gas seeps occur both within and near the edge of the GHSZ in the two areas (Figure 1). (WOD18 [50]).…”

“…Direct evidence of natural gas hydrate and gas seeps on the seafloor were found in the Rio Grande Cone [47] and in the Amazon deep-sea fan [48], in both areas in association with gas venting from the GHSZ. Living chemosynthesis-based communities in pockmarks in the Rio Grande Cone [51,52], in addition to acoustic disturbance caused by the presence of free gas at shallow depths (<10 m) below seafloor in sub-bottom profiles [53] are indicative of active methane seeps. Direct evidence of gas seepage was identified in the Amazon deep-sea fan by the presence of acoustic anomalies in the water column using multi-beam echo sounder backscatter data, which is also supported by the presence of remnants of chemosynthetic organisms at the seafloor [48].…”

Characterization of the Gut Microbiota of the Antarctic Heart Urchin (Spatangoida) Abatus agassizii

“…In contrast with González-Aravena et al (2016) who found the microbiota composition of the regular Antarctic sea-urchin Sterechinus neumayerii dominated by Alphaproteobacteria and Flavobacteria and relatively similar to the seawater's one, we noticed a shift in the dominant class of the gut content microbiota of A. agassizii with a marked enrichment in Plantomycetacia mostly represented by the Blastopirellula genus (20% of the Planctomycetes sequences). The Planctomycetes phylum (including the Planctomycetacia) has been observed at various abundances in several marine microbiotas, such as sponges (Taylor et al, 2013;Rodriguez-Marconi et al, 2015), tubeworms (Medina-Silva et al, 2018), jellyfish (Lee et al, 2018), macroalgae (Bengtsson and Øvreås, 2010) and regular sea urchins (Hakim et al, 2016). However, such a predominance has never been reported so far in marine invertebrates.…”

“…However, such a predominance has never been reported so far in marine invertebrates. Accumulating evidences suggest that Planctomycetacia belonging to the Rhodopirellula-Pirellula-Blastopirellula clade could play a major role in the degradation of sulfated polymeric carbon through sulfatase enzyme activity (Glöckner et al, 2003;Wegner et al, 2013), notably under anaerobic conditions (Elshahed et al, 2007), and in interaction with marine macro-organisms (Hempel et al, 2008;Bengtsson and Øvreås, 2010;Medina-Silva et al, 2018). Therefore, a reasonable explanation for the enrichment of Planctomycetacia in the Abatus gut content would be its high concentration in sulfated compounds coupled with a low oxygenation rate, conditions that are known to occur in other irregular sea urchins (Plante and Jumars, 1992;Thorsen, 1998).…”

Molecular and Isotopic Composition of Hydrate-Bound, Dissolved and Free Gases in the Amazon Deep-Sea Fan and Slope Sediments, Brazil

“…In Brazil, the Rio Grande Cone Gas Hydrate Province in the Pelotas Basin [13] is one of the main areas with gas hydrate deposits with associated chemosynthetic communities [14,15], and consists of the first discovery of gas hydrates in the western South Atlantic. The direct recovery of gas hydrate was performed through sediment sampling by piston coring and the results showed that the gas was mainly composed of methane of biogenic origin [13].…”