Collaborative Research: Biology and Ecology of Newly Discovered Diazotrophs in the Open Ocean

海洋的生产力受到营养物质可获得性的限制，营养物质对大气和海洋之间的碳通量有很大的影响。在以前的研究中，PI发现以前未被发现的固定氮气的单细胞蓝藻在少营养的海洋中活动和丰富。这一发现对海洋中的氮循环和“新的”氮在碳固定中的作用具有重要的意义。PI将解决三个主要问题：第一，由于未知的疾病变量，至少有两类不同的蓝藻似乎在空间和时间上是分开的。其次，地理分布和控制分布的因素尚不清楚，因此还不清楚这些生物应该如何纳入生物地球化学模型。最后，其中一组蓝藻似乎在白天固定了N2，这让以前仅限于讨论毛霉菌的同步固氮和光合作用之谜重新出现。

The productivity of the oceans is limited by the availability of nutrients, which hasimplications for the fluxes of carbon between the atmosphere and oceans. In a previousaward the PIs found that previously unrecognized N2-fixing unicellular cyanobacteriaare active and abundant in oligotrophic oceans. This finding has important implicationsfor nitrogen cycling in the oceans and for the role of "new" nitrogen in carbon fixation.The PIs will address three major issues: First, there are at least two distinct groups ofcyanobacteria that appear to be separated in space and time, due to unknownecological variables. Second, the geographic distribution and factors controlling thedistribution are unknown, so it is not clear how these organisms should be included inbiogeochemical models. Finally, one of the groups of cyanobacteria appears to fix N2during the day, which revives the enigma of simultaneous nitrogen fixation andphotosynthesis that was previously limited to discussions of Trichodesmium.