Bubble transport Mechanism: Indications for a gas bubble-mediated inoculation of benthic methanothrophs into the water column

Schmale, Oliver, Leifer, Ira, Schneider von Deimling, Jens, Stolle, Christian, Krause, Stefan, Kießlich, Katrin, Fram, Andreas and Treude, Tina (2015) Bubble transport Mechanism: Indications for a gas bubble-mediated inoculation of benthic methanothrophs into the water column Continental Shelf Research, 103 . pp. 70-78. DOI 10.1016/j.csr.2015.04.022.

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Supplementary data:

Abstract

Highlights

• A new bentho-pelagic transport mechanism of microorganisms is hypothesized
• A bubble transport hypothesis was tested using a new gas bubble-collecting device
• Bubble-mediated transport rate of methanotrophs was quantified at a gas vent
• The Bubble Transport Mechanism may influence the pelagic methane sink

Abstract

The importance of methanotrophic microorganisms in the sediment and water column for balancing marine methane budgets is well accepted. However, whether methanotrophic populations are distinct for benthic and pelagic environments or are the result of exchange processes between the two, remains an area of active research. We conducted a field pilot study at the Rostocker Seep site (Coal Oil Point seep field, offshore California, USA) to test the hypothesis that bubble-mediated transport of methane-oxidizing microorganisms from the sediment into the water column is quantifiable. Measurements included dissolved methane concentration and showed a strong influence of methane seepage on the water-column methane distribution with strongly elevated sea surface concentrations with respect to atmospheric equilibrium (saturation ratio ~17,000%).

Using Catalyzed Reporter Deposition Fluorescence In Situ Hybridization (CARD FISH) analysis, aerobic methane oxidizing bacteria (MOB) were detected in the sediment and the water column, whereas anaerobic methanotrophs (ANME-2) were detected exclusively in the sediment. Critical data for testing the hypothesis were collected using a novel bubble catcher that trapped naturally emanating seep gas bubbles and any attached particles approximately 15 cm above the seafloor. Bubble catcher experiments were carried out directly above a natural bubble seep vent and at a nearby reference site, for which an “engineered” nitrogen bubble vent without sediment contact was created. Our experiments indicate the existence of a “Bubble Transport Mechanism”, which transports MOB from the sediment into the water column. In contrast, ANME-2 were not detected in the bubble catcher. The Bubble Transport Mechanism could have important implications for the connectivity between benthic and pelagic methanotrophic communities at methane seep sites.

Document Type: Article
Additional Information: WOS:000356744400007
Keywords: gas vent, methane, bentho-pelagic bubble transport, methanotrophs
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence > FO-R03
OceanRep > The Future Ocean - Cluster of Excellence > FO-R07
OceanRep > The Future Ocean - Cluster of Excellence > FO-R05
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
OceanRep > The Future Ocean - Cluster of Excellence > FO-R09
OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
DOI etc.: 10.1016/j.csr.2015.04.022
ISSN: 0278-4343
Projects: Future Ocean
Date Deposited: 03 Sep 2014 09:28
Last Modified: 26 Mar 2017 18:50
URI: http://eprints.uni-kiel.de/id/eprint/25540

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