Abstract
In a variety of marine ecosystems, microbial eukaryotes play important ecological roles; however, our knowledge of their importance in deep-sea methane seep ecosystems is limited. Microbial eukaryotes have the potential to influence microbial community composition and diversity by creating habitat heterogeneity, and may contribute to carbon cycling through grazing or symbiotic associations with microorganisms. In this study, we characterized the distribution, substrate variability and ecology of a particular group of microbial eukaryotes, known as folliculinid ciliates, at methane seeps along the eastern Pacific margin. Folliculinid ciliates were recently recognized as an abundant and ecologically important component of hydrothermal vent ecosystems, but their ecology in methane seeps has not been examined. Folliculinid ciliates inhabited methane seeps from Costa Rica to Oregon, suggesting a broad distribution in the eastern Pacific. Using phylogenetic analyses of the 18S rRNA gene, two different species of folliculinid were identified. Folliculinids occupied a range of physical substrates, including authigenic carbonate rocks, shells of dead vesicomyid clams, polychaete tubes and gastropod shells. Molecular analysis of folliculinid associated microorganisms (16S rRNA and particulate methane monooxygenase) revealed that these ciliates not only influence overall microbial diversity, but also and have a specific relationship with bacteria in the ‘Deep sea-2’ methanotroph clade. Natural δ13C isotope signatures of folliculinids (-35‰) and their 13C-enrichment patterns in shipboard 13CH4 stable isotope-probing experiments indicated these ciliates and their associated microbes are involved in cycling methane-derived carbon. Folliculinids were significantly enriched in 13C after the addition of 13CH4 over short-term (3-8 day) incubations. Together, these results suggest that folliculinid ciliates represent a previously overlooked contributor to the ecology and biogeochemical cycling of deep-sea methane seep ecosystems.
Highlights
Methane seeps are geomorphologic features and novel ecosystems common to most of the world’s continental margins (German et al, 2011). Due to their novel metabolic activities, methane seep bacteria and archaea have extremely high rates of in situ primary production, perform important roles in biogeochemical cycling, and provide trophic support to unique, dense animal assemblages which contribute to regional biodiversity patterns along continental margins (Levin, 2005; Cordes et al, 2010; Grupe et al, 2015)
The low variability of sequences within each of the seep folliculinid clades suggests that each can be regarded as a species with different distributions along the eastern Pacific margin
Distribution and Substrate Variability of Seep-Associated Folliculinid Ciliates. This survey revealed that folliculinid ciliates have a broad distribution across seep habitats in the eastern Pacific, and occupy a range of authigenic and biogenic hard substrates within methane seeps
Summary
Methane seeps are geomorphologic features and novel ecosystems common to most of the world’s continental margins (German et al, 2011). Due to their novel metabolic activities, methane seep bacteria and archaea have extremely high rates of in situ primary production (relative to the surrounding deep sea), perform important roles in biogeochemical cycling, and provide trophic support to unique, dense animal assemblages which contribute to regional biodiversity patterns along continental margins (Levin, 2005; Cordes et al, 2010; Grupe et al, 2015). We are just beginning to investigate how these marine protists influence the structure and function of chemosynthetic ecosystems (e.g., Edgcomb et al, 2010, 2011)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
