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首页> 外文期刊>Nature >Counterintuitive carbon-to-nutrient coupling in an Arctic pelagic ecosystem
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Counterintuitive carbon-to-nutrient coupling in an Arctic pelagic ecosystem

机译：北极中上层生态系统中碳-营养耦合的直觉

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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 carbonitrogen ratio of inorganic consumption and release of dissolved organic matter may increase in a high-CO_2 world. This will, however, yield a negative feedback on atmospheric CO_2 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 het-erotrophic processes.
机译：预测海洋在全球碳循环中的作用，需要了解碳与生物地球化学过程中生长限制元素之间的化学计量耦合。最近对此类知识的补充是，在高CO_2的世界中，无机物消耗和溶解的有机物释放的碳/氮比可能会增加。但是，只有在多余的有机物质逃离了光合区内的矿化条件时，这才会对大气中的CO_2产生负反馈。在这里，我们展示了在北极中上层生态系统的背景下，添加的可降解有机碳的命运和影响如何严重依赖于微生物食物网的状态。当细菌的生长速度受到矿物质营养的限制时，系统中就会积累额外的有机碳。但是，当细菌受到有机碳的限制时，添加不稳定的溶解有机碳会降低浮游植物的生物量和活性，并降低总有机碳的积累速率，这可以解释为刺激的细菌竞争矿物质养分的结果。这种反直觉的“更多的有机碳提供更少的有机碳”效应在以硅藻为主的系统中尤为突出，在该系统中浮游植物生产中的碳/矿质养分比很高。我们的研究结果突显了如何描述海洋碳循环的当前和未来状态需要对自养和异养过程中碳与生长受限的矿质营养素之间的化学计量耦合进行详细了解。

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