The oceans have absorbed nearly half of the fossil fuel carbon dioxide (CO2) emitted into the atmosphere since pre-industrial times1, causing a measurable reduction in seawater pH and
carbonate saturation2. If CO2 emissions continue to rise at current rates, upper ocean pH will decrease to levels lower than have existed for tens of millions of years and critically at a rate of change 100 times greater than at any time over this period3.
A consequence of the resulting increase in ocean primary production include lower nutritional value of organic matter for consumption by higher trophic organisms having potentially deleterious effects on marine ecosystem functioning and dynamics.
The study reveals that dissolved inorganic carbon (DIC) consumption of a natural plankton community maintained in mesocosm enclosures at initial CO2 partial pressures (pCO2) of 350, 700, and 1050 µatm increases with rising CO2. The community consumed up to 39% more DIC at elevated pCO2 compared to present levels, while nutrient uptake remained the same. The stoichiometry of carbon to nitrogen drawdown (C:N) increased from 6.0 at low CO2 to 8.0 at high CO2, thus exceeding the Redfield C:N ratio of 6.6 in today’s ocean 7. This excess carbon consumption was associated with higher loss of organic carbon from the upper layer of the stratified mesocosms. If applicable to the naturalenvironment, the observed responses have implications for a variety of marine biological and biogeochemical processes and underscore the importance of biologically-driven feedbacks in the ocean to global change.
Recent studies have shown effects of ocean acidification on a variety of marine life forms, in particular calcifying organisms 4-6. Consequences at the community to ecosystem level, on the other hand, are largely unknown.
U. Riebesell (1), K. G. Schulz (1), R.G.J. Bellerby (2), M. Botros (1), P. Fritsche 1, M. Meyerhöfer (1), C. Neil (l) (2), G. Nondal (2) ,(3), A. Oschlies (2), J. Wohlers (1), E. Zöllner (1)
(1) Leibniz Institute of Marine Sciences,
(2) Bjerknes Centre for Climate Research,
(3) Geophysical Institute, University of Bergen,
Reference:
U. Riebesell, K. G. Schulz, R. G. J. Bellerby M. Botros1, P. Fritsche1, M. Meyerho¨fer, C. Neill, G. Nondal, A. Oschlies, J. Wohlers & E. Zo¨llner. Enhanced biological carbon consumption in a high CO2 ocean. NATURE doi: 10.1038/nature06267
Enhanced biological carbon consumption in a high CO2 ocean
In this Nature article Bellerby and colleagues show how ocean acidification leads to carbon overconsumption in a pelagic ecosystem which they show may be a significant oceanic feedback reducing the rate of future atmospheric carbon dioxide increase.
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