Siboglinidae Tubes as an Additional Niche for Microbial Communities in the Gulf of Cádiz—A Microscopical Appraisal

Abstract

Siboglinids were sampled from four mud volcanoes in the Gulf of Cádiz (El Cid MV, Bonjardim MV, Al Gacel MV, and Anastasya MV). These invertebrates are characteristic to cold seeps and are known to host chemosynthetic endosymbionts in a dedicated trophosome organ. However, little is known about their tube as a potential niche for other microorganisms. Analyses by scanning and transmission electron microscopy showed dense biofilms on the tube in Al Gacel MV and Anastasya MV specimens by prokaryotic cells. Methanotrophic bacteria were the most abundant forming these biofilms as further supported by 16S rRNA sequence analysis. Furthermore, elemental analyses with electron microscopy and energy-dispersive X-ray spectroscopy point to the mineralization and silicification of the tube, most likely induced by the microbial metabolisms. Bacterial and archaeal 16S rRNA sequence libraries revealed abundant microorganisms related to these siboglinid specimens and certain variations in microbial communities among samples. Thus, the tube remarkably increases the microbial biomass related to the worms and provides an additional microbial niche in deep-sea ecosystems.

The Interactive Role of Hydrocarbon Seeps, Hydrothermal Vents and Intermediate Antarctic/Mediterranean Water Masses on the Distribution of Some Vulnerable Deep-Sea Habitats in Mid Latitude NE Atlantic Ocean

“…Very low DO values of 0.64 mL•L −1 observed on deep-water mud volcanoes as Bonjardim in the GoC are closely to anoxia suggesting the intense activity of methane seeps (Figure 14D). If methane seeps are intense and/or undercurrents are weak in such deep waters, then low oxygen conditions prevail above seafloor and chemosynthesis-based habitats are only composed by colonies of Siboglinidae tubes [67]. However, in areas of methane seeps influenced by strong intermediate undercurrents (Figure 14D), co-occurrence of chemosynthesis-based and scleractinian-gorgonian aggregations has been detected as in this study and other MVs of the Gulf of Mexico [68].…”

Microbial utilization of rare earth elements at cold seeps related to aerobic methane oxidation

“…o u r n a l P r e -p r o o f Journal Pre-proof There is plentiful evidence that active microbial activity takes place in the anterior part of siboglinid tubes at cold seeps. For instance, recent studies conducted at methane seeps recently identified Methylococcales and other methanotrophic bacteria as an abundant microbial group in the anterior portion of chitin tubes of siboglinids, including Escarpia southwardae(Medina-Silva et al, 2018;Rincón-Tomás et al, 2020). In addition to the primary sulphur-oxidizing symbionts present in the animal itself, the presence of abundant methanotrophic bacteria in the upper part of the tube of a Lamellibrachia species was also supported using methanotroph-specific molecular probes and sequencing of a subunit of methane monooxygenase(Duperron et al, 2009).…”

Phoronids and their tubes harbor distinct microbiomes compared to surrounding sediment

“…[26]) and shrimp (e.g., Upogebia sp. [27]), have described important roles for the microbiome in host-environment interactions including metal resistance and sulfur cycling [28–30]. Often the microenvironment of the tube or burrow created by these marine organisms is found to have a distinct microbiome from surrounding sediments [22,23,28,31].…”