The paper, resulting from collaboration between the University of Bergen and Bjerknes Centre scientists, reports on how the Arctic marine ecosystems respond to variations in the supply of organic carbon and nutrients. The experiment was conducted at the Ny Ålesund biological station.
According to Dr. Richard Bellerby at the Bjerknes Centre, the research team was surprised by the counterintuitive response discovered during the study. An earlier study by the group , also presented in Nature showed that high CO2 seawater enhances biological carbon consumption due to increased organic carbon production by marine phytoplankton, and thereby leading to a reduction in the rate of future CO2 emissions. This latest study shows that this enhanced organic carbon production may, ultimately, lead to a net reduction in the removal of carbon away from the ocean surface.
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| The experiment was conducted at the Ny Ålesund biological station (All photos: Richard Bellerby). |
Bacteria win battle over nutrients
The oceans absorb about a quarter of fossil fuel CO2 emissions emitted into the atmosphere, and therefore play a significant role in regulating global warming. While marine primary production (e.g. phytoplankton) binds CO2, the study showed that when more organic carbon was available it fuelled bacterial production. In sum, the total amount of organic carbon produced by the ecosystem was reduced. This was identified by the authors to be a result of the increased competitive edge of bacteria, which were winning the race over the phytoplankton for the available nutrients. Thus the predicted increase in organic carbon supply into the Arctic Ocean may result in a reduction – and not an increase - in carbon removal in the ocean.
The Arctic sensitive to changing conditions
The Arctic region is seen as particular sensitive to climate change due to reduction in sea ice, increased UV radiation and ocean acidification and to variations in nutrient and carbon supply that will impact on ecosystems already low in biodiversity. Higher temperatures are predicted to result in an increased supply of nutrients and organic carbon to the Arctic Ocean from land due to melting of permafrost. A reduction of the competitiveness of phytoplankton in the Arctic Ocean will reduce the potential food supply for fisheries. The presently held view that a warming of the Arctic Ocean will automatically result in a northward movement of fisheries from the Barents Sea should therefore be questioned.
The findings from the present Nature paper also suggest a heightened sensitivity of Arctic marine ecosystems to hydrocarbon supply from oil spills and leakage. The likelihood for both chronic and acute organic carbon supply into the Arctic ecosystems will increase with the planned exploitation of oil reserves.
Improved understanding of how biological systems will react to changing environmental conditions, including modifications to light fields and nutrient supply, higher temperatures and ocean acidification, is needed to better predict the oceanic feedback to climate change.
Referance:
- Department of Biology, University of Bergen, Jahnebakken 5PO Box 7800, 5020 Bergen, Norway
- Bjerknes Centre for Climate Research, Allégaten 55, 5007 Bergen, Norway
- Geophysical Institute, University of Bergen, Allégaten 70, 5007 Bergen, Norway
- Institute of Marine Research, PO Box 1870, Nordnes 5817 Bergen, Norway
- Laboratoire d'Océanographie et de Biogéochimie, UMR6535-CNRS, Campus de Luminy, Case 901, 13288 Marseille CEDEX09, France