一項將可降解有機碳添加進北極水域的實驗獲得了反直覺的發(fā)現(xiàn)：在某些條件下,，碳的添加實際上會減少生態(tài)系統(tǒng)中的總有機碳。實驗結果取決于食物鏈內物種相互作用以及它們怎樣受營養(yǎng)供應的影響,。當?shù)V物營養(yǎng)有限時，有機碳會在系統(tǒng)中積累,，而在一個有機碳有限的系統(tǒng)中,，海洋細菌能夠競爭過浮游植物，其凈結果為總有機碳數(shù)量減少,。
這一結果凸現(xiàn)了這樣一個關系,，即對海洋碳循環(huán)當前和未來狀態(tài)的描述，怎樣依賴于對海洋食物鏈內的碳與限制生長的礦物營養(yǎng)之間的化學計量耦合的認識,。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature 455, 387-390 (18 September 2008) | doi:10.1038/nature07235
Counterintuitive carbon-to-nutrient coupling in an Arctic pelagic ecosystem
T. F. Thingstad, R. G. J. Bellerby, G. Bratbak, K. Y. B?rsheim, J. K. Egge, M. Heldal, A. Larsen, C. Neill, J. Nejstgaard, S. Norland1, R.-A. Sandaa1, E. F. Skjolda, T. Tanaka, R. Thyrhaug1 & B. T?pper
Predicting the ocean's role in the global carbon cycle requires an understanding of the stoichiometric coupling between carbon and growth-limiting elements in biogeochemical processes. A recent addition to such knowledge is that the carbon/nitrogen ratio of inorganic consumption and release of dissolved organic matter may increase in a high-CO2 world1. This will, however, yield a negative feedback on atmospheric CO2 only if the extra organic material escapes mineralization within the photic zone. Here we show, in the context of an Arctic pelagic ecosystem, how the fate and effects of added degradable organic carbon depend critically on the state of the microbial food web. When bacterial growth rate was limited by mineral nutrients, extra organic carbon accumulated in the system. When bacteria were limited by organic carbon, however, addition of labile dissolved organic carbon reduced phytoplankton biomass and activity and also the rate at which total organic carbon accumulated, explained as the result of stimulated bacterial competition for mineral nutrients. This counterintuitive 'more organic carbon gives less organic carbon' effect was particularly pronounced in diatom-dominated systems where the carbon/mineral nutrient ratio in phytoplankton production was high. Our results highlight how descriptions of present and future states of the oceanic carbon cycle require detailed understanding of the stoichiometric coupling between carbon and growth-limiting mineral nutrients in both autotrophic and heterotrophic processes.
