Microbial Responses to Ocean Deoxygenation

由于气候变暖和陆地营养物质通量的增加，海洋正在失去氧气。海洋生物将最强烈地感受到脱氧的直接影响，它们将面临与呼吸减弱、栖息地压缩和丧失、免疫抑制、生殖受损、疾病和死亡率增加以及生长减慢有关的挑战。间接影响延伸到陆地上的生命，包括气候反馈和改变的生物地球化学循环。对人类来说，直接影响来自世界渔业对脱氧的脆弱性，因此对全球粮食安全构成严重风险。然而，海洋脱氧的具体影响将受到海洋微生物及其对氧气减少的反应的强烈影响。这些反应是高度不确定的，因此我们预测和管理海洋脱氧影响的能力也是如此。拟议的研究将结合最先进的地球化学和微生物学分析，以确定东北亚北极太平洋(NESAP)海洋氧气损失的震中微生物对脱氧的反应。北冰洋是海洋中氧气损失最严重的省份，北冰洋最低含氧区的核心正在接近一个临界点，在这个临界点上，厌氧微生物的新陈代谢将进行。NESAP是一个定义微生物对脱氧反应的理想省份，因为可以在垂直方向上发现一系列的氧合状态，作为深度的函数，在横向上也可以在离岸距离上找到。NESAP可以从不列颠哥伦比亚省海岸访问，也可以通过时间序列实验访问，其中还保存了丰富的历史数据档案。拟议的研究将加强这些时间序列实验，分析旨在：1)定量确定海洋细菌对氧气下降的生理反应；2)确定氧气的可用性如何影响海洋食物网底部的营养结构；3)确定NESAP中的营养循环对氧气下降的反应；以及4)重建NESAP中的历史氧合状态。拟议研究的结果将包括描述微生物对海洋脱氧的反应的定性和定量模型，以便能够更好地预测未来的脱氧及其影响。这一信息对加拿大渔业的管理至关重要，对粮食安全和应对气候变化具有影响。通过互动和向渔业和海洋部进行简报，这项研究将为未来的管理政策提供信息。除渔业政策外，关于微生物氧代谢的信息可更广泛地扩展到可利用微生物氧气控制以改善健康和工艺结果的各个部门。重要的是，拟议的研究将导致两个新成立的HQP，具有跨学科的专业知识，准备解决多个部门的问题。

The oceans are losing oxygen as the combined result of warming climate and increasing nutrient fluxes from land. Direct impacts of deoxygenation will be felt most acutely by marine organisms that will face challenges related to diminished respiration, habitat compression and loss, immune suppression, impaired reproduction, increased disease and mortality, and reduced growth. Indirect effects extend to life on land and include climate feedbacks and altered biogeochemical cycles. For humans, direct affects come from the vulnerability of the world's fisheries to deoxygenation, which thus poses serious risks to global food security. The specific impacts of ocean deoxygenation, however, will be strongly influenced by marine microorganisms and their responses to declining oxygen. These responses are highly uncertain, and thus so too is our ability to forecast and manage the impacts of ocean deoxygenation. The proposed research will couple state-of-the-art geochemical and microbiological analyses to determine microbial responses to deoxygenation in the epicenter of ocean oxygen lossthe North-Eastern Sub-Arctic Pacific ocean (NESAP). The NESAP is the oceanographic province with the most intense oxygen loss, and the core of the NESAP oxygen minimum zone is nearing a tipping point, at which anaerobic microbial metabolisms will engage. The NESAP is an ideal province in which to define microbial responses to deoxygenation, since a range of oxygenation states can be found both vertically as a function of depth, and laterally with distance off-shore. The NESAP can be accessed from the BC coast and through time-series experiments, which also house a rich archive of historical data. The proposed research will augment these time-series experiments with analyses designed to: 1) quantitatively determine the physiological response of marine bacteria to declining oxygen; 2) determine how oxygen availability influences trophic structure at the base of the marine food web; 3) determine the response of nutrient cycling in the NESAP to declining oxygen; and 4) reconstruct historical oxygenation states in the NESAP. The outcomes of the proposed research will include qualitative and quantitative models that describe microbial responses to ocean deoxygenation to enable better predictions of future deoxygenation and its impacts. This information is critical for the management of Canadian fisheries with implications for food security and responses to climate change. Through interactions and briefings to Department of Fisheries and Oceans, this research will inform future management policy. Beyond fisheries policy, information on microbial oxygen metabolism is more broadly extensible across sectors where microbial oxygen control can be leveraged for better health and process outcomes. Importantly, the proposed research will lead to 2 newly minted HQP with transdisciplinary expertise poised to tackle problems across multiple sectors.