Methanogenic Communities in Submarine Permafrost of the Laptev Sea Shelf, Siberia
Location of the boreholes along the drilling transect
Drilling rig on the Laptev Sea ice (photo by V. Rachold, IASC)
Russian-German drilling camp, Laptev Sea, Siberia (photo by V. Rachold, IASC)
Funding
BMBF (2003-2006); AWI
Cooperation
Michael Grigoriev & Victor Kunitsky
Geochryology
Permafrost Institute, SB-RAS
Yakutsk, Russia
Alexander Deriviagin
Geochryology
Moscow State University, RAS
Moscow, Russia
Paul Overduin
Geochemistry
Alfred Wegener Institute for Polar and Marine Research
Potsdam, Germany
Christian Knoblauch
Biogeochemistry
Institute of Soil Science
University of Hamburg, Germany
Background
Coastal erosion and sea level rise created the shallow shelf of the Laptev Sea whose bottom is formed by the formerly terrestrial permafrost. Flooding of the cold (-5 to -15°C) terrestrial permafrost with relatively warm (-0.5 to ‑2°C) saline water from the Laptev Sea changed the system profoundly and resulted in a warming of the permafrost. Fresh sediment, originating from coastal erosion, the discharge of the large arctic rivers and marine organic material is deposited on its surface, and the permafrost is getting increasingly buried under fresh material. Warming of the formerly terrestrial permafrost on the sea bottom might enable and enhance microbial turnover in these in part carbon rich sediments, resulting in an increased production of CO2 and CH4. Since the submarine permafrost originates from frozen terrestrial Holocene and Pleistocene sediments that were flooded during the Holocene sea level rise and after coastal erosion, the autochthonous microbial community should be of terrestrial origin. However, the unfrozen sediments on top of the (submarine) permafrost are of marine origin and represent a completely different environment with most likely different microbial communities.
Due to its poor accessibility, studies on the microbial diversity and activity in submarine permafrost neither have been conducted by cultivation dependent methods nor by cultivation independent molecular approaches. Therefore, the microbial abundance and diversity in the carbon rich permafrost as well as the significance of microbial activity and response to rising temperatures is completely unknown.
Outcomes
Overduin P. (2007) Russian-German Cooperation SYSTEM LAPTEV SEA: The Expedition COAST I. In: Schirrmeister L. (ed.) Expeditions in Siberia in 2005. Reports on Polar and Marine Research 550, 1-40.
Koch K., Knoblauch C. and Wagner D. (2009) Methanogenic community composition and anaerobic carbon turnover in submarine permafrost sediments of the Siberian Laptev Sea. Environmental Microbiology 11, 657-668.