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Impact of temperature, CO2, and iron on nutrient uptake by a late-season microbial community from the Ross Sea, Antarctica
Aquatic Microbial Ecology ( IF 1.4 ) Pub Date : 2018-11-13 , DOI: 10.3354/ame01886
JL Spackeen , RE Sipler , EM Bertrand , K Xu , JB McQuaid , NG Walworth , DA Hutchins , AE Allen , DA Bronk

ABSTRACT: The Southern Ocean is rapidly changing as a result of rising sea surface temperatures, elevated CO2 concentrations, and modifications to iron sources and sinks. The Southern Ocean has seasonally high rates of primary production, making it critical to determine how changes will impact biogeochemical rate processes in this important sink for CO2. During the austral summer, we measured nitrogen and carbon uptake rates by a late-season Ross Sea microbial community under different potential climate change conditions. A natural microbial assemblage was collected from the ice edge, and grown using a semi-continuous culturing followed by a continuous culturing ‘ecostat’ approach. The individual and combined impacts of temperature elevation and iron addition were tested during both approaches, and CO2 level was also manipulated during the continuous experiment. Nutrient concentrations and biomass parameters were measured throughout both experiments. During the continuous experiment we also measured uptake rates of nitrate (NO3-) and dissolved inorganic carbon (DIC) by 2 size classes (0.7-5.0 and >5.0 µm) of microorganisms. Of the parameters tested, temperature elevation had the largest impact, significantly increasing NO3- and DIC uptake rates by larger microorganisms. Iron addition was also important; however, the magnitude of its impact was greater when temperature was also changed. These results indicate that NO3- and DIC uptake rates may increase as sea surface warming occurs in the Southern Ocean, and thus have important implications for estimating new production and potential carbon uptake and eventual export to the deep sea.

中文翻译:

温度,CO2和铁对南极罗斯海后期微生物群落养分吸收的影响

摘要:由于海面温度升高,CO 2浓度升高以及铁源和汇的修改,南大洋正在迅速变化。南部海洋的季节性初级生产力很高,因此至关重要的是确定变化将如何影响这一重要的CO 2汇的生物地球化学速率过程。。在南方夏季,我们在不同的潜在气候变化条件下,测量了季末期罗斯海微生物群落的氮和碳吸收率。从冰边缘收集天然微生物集合,并使用半连续培养然后通过连续培养的“ ecostat”方法进行生长。在两种方法中均测试了温度升高和铁添加的单独影响和组合影响,并且在连续实验期间还控制了CO 2含量。在两个实验中均测量了营养物浓度和生物量参数。在连续实验中,我们还摄取(NO硝酸的速率测得的3 -)和2种大小级别(0.7-5.0和> 5.0 µm)的微生物溶解的无机碳(DIC)。测试的参数,温度升高有最大的影响,显著增加NO 3 -由较大的微生物和DIC的吸收率。铁的添加也很重要。然而,当温度也改变时,其影响的程度更大。这些结果表明,NO 3 -和DIC的吸收速率海面变暖在南大洋时可能会增加,从而对新的生产和潜在的碳吸收和最终的出口估计深海重要的意义。
更新日期:2018-11-13
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