Microbial biofilms associated with fluid chemistry and megafaunal colonization at post-eruptive deep-sea hydrothermal vents

Abstract

At deep-sea hydrothermal vents, reduced, super-heated hydrothermal fluids mix with cold, oxygenated seawater. This creates temperature and chemical gradients that support chemosynthetic primary production and a biomass-rich community of invertebrates. In late 2005/early 2006 an eruption occurred on the East Pacific Rise at 9° 50'N, 104° 17'W. Direct observations of the post-eruptive diffuse-flow vents indicated that the earliest colonizers were microbial biofilms. Two cruises in 2006 and 2007 allowed us to monitor and sample the early steps of ecosystem recovery. The main objective of this work was to characterize the composition of microbial biofilms in relation to the temperature and chemistry of the hydrothermal fluids and the observed patterns of megafaunal colonization. The area selected for this study had local seafloor habitats of active diffuse flow (in-flow) interrupted by adjacent habitats with no apparent expulsion of hydrothermal fluids (no-flow). The inflow habitats were characterized by higher temperatures (1.6-25.2 °C), and H 2 S concentrations (up to 67.3 µM) than the no-flow habitats, and the microbial biofilms were dominated by chemosynthetic Epsilonproteobacteria. The no-flow habitats had much lower temperatures (1.2-5.2 °C), and H 2 S concentrations (0.3-2.9 µM), and Gammaproteobacteria dominated the biofilms. Siboglinid tubeworms colonized only inflow habitats, while they were absent at the no-flow areas, suggesting a correlation between siboglinid tubeworm colonization, active hydrothermal flow, and the composition of chemosynthetic microbial biofilms.

The early conversion of deep-sea wood falls into chemosynthetic hotspots revealed by in situ monitoring

“…Wood substrates further distinguish from whale bones by the rapid depletion of sulfide from the surface, even though it continues to be produced deeper in wood, resulting of the activity of Xylophaga spp. Among deep-sea hard substrate habitats sustaining sulfide-oxidizing bacterial biofilms, the surface of wood falls apparently share more similarities with the fresh basalts exposed to diffuse hydrothermal flows which similarly display micromolar sulfide conditions at temperature a few degrees above ambient and typically last a few months to 1 years after a volcanic eruption 27 , 28 .…”

Hydrothermal Energy Transfer and Organic Carbon Production at the Deep Seafloor

“…Yet, the most remarkable characteristics of hydrothermal habitats in the months following the eruption is that LT-diffuse flows hosting microbial biofilms spread over large surface of the cooling lava (Tunnicliffe et al, 1997;Shank et al, 1998;Gulmann et al, 2015). So far, very limited chemical data are available for these early LT-diffuse flows but the high H 2 S/T reported for such microbial habitats one year after for the last eruption on EPR 9 • 50 N exceeds that of mature LT-diffuse flows (Mullineaux et al, 2012;O'Brien et al, 2015). Early post-eruption conditions are coupled with high colonization rates of microbial biofilm formation, as revealed by the formation of sulfur mats on new basalt surfaces exposed to diffuse flows within days (Gulmann et al, 2015;O'Brien et al, 2015).…”

“…So far, very limited chemical data are available for these early LT-diffuse flows but the high H 2 S/T reported for such microbial habitats one year after for the last eruption on EPR 9 • 50 N exceeds that of mature LT-diffuse flows (Mullineaux et al, 2012;O'Brien et al, 2015). Early post-eruption conditions are coupled with high colonization rates of microbial biofilm formation, as revealed by the formation of sulfur mats on new basalt surfaces exposed to diffuse flows within days (Gulmann et al, 2015;O'Brien et al, 2015). Pioneer colonist communities are composed almost exclusively of Campylobacteria such as Arcobacter and Sulfurovum.…”

Potential Mitigation and Restoration Actions in Ecosystems Impacted by Seabed Mining

“…Original microbial composition living in the subsurface flow could allow for the most similar colonisation and succession patterns, be it microbial, meio-, macro-or megafaunal. If local fluid exits get clogged, fluids will get expelled elsewhere, but their biogeochemical composition will be different, as will subsequent colonising megafauna (Nakajima et al, 2015;O'Brien et al, 2015). The impossibility to estimate response time for new organisms to arrive, the lack of knowledge on the time needed for full or partial recovery and the (dis)similarity to the original population are disadvantages.…”