The Changing Arctic Ocean Seafloor (ChAOS) - how changing sea ice conditions impact biological communities, biogeochemical processes and ecosystems

ChAOS将量化海冰覆盖变化对有机质质量、底栖生物多样性、碳和营养库的生物转化以及由此产生的北冰洋海底生态系统功能的影响。我们将通过确定出口到北极海底的有机物（OM）和相关营养物质的数量、来源和生物利用度来实现这一目标；它在底栖生物食物链中的消耗、转化和循环；以及它最终被掩埋或回收到水柱中。我们将通过以下方式研究这些耦合的生物和生物地球化学过程：(i)对相交冰缘的具有代表性的北极陆架海洋栖息地的详细研究，（ii）大规模的原位验证研究和船上实验，（iii）将确定因果关系和机制的操作实验室实验，（iv）分析加拿大，(5)我们将把对生物多样性、生物地球化学途径和营养循环的控制和影响的新认识整合到建模方法中，探索北极海冰变化如何在区域尺度上改变生态系统。我们将把重点放在北冰洋的部分地区，在那里，海冰覆盖的急剧变化是主要的环境控制因素，例如巴伦支海。共同的实地考察活动将构成我们研究活动的核心。虽然我们首选的重点区域是沿东经30度的巴伦支海的南北向样带，那里的冰扩张和退缩是众所周知的，并且是安全的，但我们还将使用额外的巡航到挪威具有相似沉积物和水条件的地点，检索关键物种进行扩展的实验室实验，以考虑未来的环境强迫。重要的是，我们的活动设计不是针对特定地点的，这使得我们的方法可以应用于其他具有类似区域特征的地区。这种灵活性使所有方案联盟（远洋或底栖）之间的协调活动范围最大化，如果对《机会公告》的所有反应都得到评价后，北极大陆架的其他地区更合适的话。为了支持我们的实地活动，并根据我们的国际合作伙伴（挪威、加拿大、美国、意大利、波兰和德国）对实地样本和数据的分析，我们将进行一系列严格限制的实验室实验，将孵化的天然沉积物暴露在最有可能随着海冰覆盖变化而变化的环境条件下。并分析生物学和生物地球化学对当前和未来环境（如海洋酸化、变暖）这些诱发变化的反应。我们将利用国际项目合作伙伴提供的现有补充数据集，对北冰洋不同地区进行更广泛的时空覆盖。英国8家领先研究机构的专业知识（微生物学家、地球化学家、生态学家、建模师）和设施的独特结合，将使我们能够在作为底栖生态系统食物来源的出口OM的数量和质量之间建立新的联系，在底栖生物的全谱中对生物多样性和生态系统功能的反应，以及对循环和埋藏池之间碳和营养物质分配的影响。为了将底栖生物子系统与整个北冰洋联系起来，我们将与研究水柱、底栖生物环境（及其相互作用）和陆地-海洋过渡中的生物地球化学过程的互补项目建立密切联系。这将提供综合数据集和过程理解，以及开发预测模型（例如MEDUSA）所需的新颖、数字高效的升级工具，这些模型允许将海底定量纳入北冰洋变化的环境预测。

ChAOS will quantify the effect of changing sea ice cover on organic matter quality, benthic biodiversity, biological transformations of carbon and nutrient pools, and resulting ecosystem function at the Arctic Ocean seafloor. We will achieve this by determining the amount, source, and bioavailability of organic matter (OM) and associated nutrients exported to the Arctic seafloor; its consumption, transformation, and cycling through the benthic food chain; and its eventual burial or recycling back into the water column. We will study these coupled biological and biogeochemical processes by combining (i) a detailed study of representative Arctic shelf sea habitats that intersect the ice edge, with (ii) broad-scale in situ validation studies and shipboard experiments, (iii) manipulative laboratory experiments that will identify causal relationships and mechanisms, (iv) analyses of highly spatially and temporally resolved data obtained by the Canadian, Norwegian and German Arctic programmes to establish generality, and (v) we will integrate new understanding of controls and effects on biodiversity, biogeochemical pathways and nutrient cycles into modelling approaches to explore how changes in Arctic sea ice alter ecosystems at regional scales. We will focus on parts of the Arctic Ocean where drastic changes in sea ice cover are the main environmental control, e.g., the Barents Sea. Common fieldwork campaigns will form the core of our research activity. Although our preferred focal region is a N-S transect along 30 degree East in the Barents Sea where ice expansion and retreat are well known and safely accessible, we will also use additional cruises to locations that share similar sediment and water conditions in Norway, retrieving key species for extended laboratory experiments that consider future environmental forcing. Importantly, the design of our campaign is not site specific, allowing our approach to be applied in other areas that share similar regional characteristics. This flexibility maximizes the scope for coordinated activities between all programme consortia (pelagic or benthic) should other areas of the Arctic shelf be preferable once all responses to the Announcement of Opportunity have been evaluated. In support of our field campaign, and informed by the analysis of field samples and data obtained by our international partners (in Norway, Canada, USA, Italy, Poland and Germany), we will conduct a range of well-constrained laboratory experiments, exposing incubated natural sediment to environmental conditions that are most likely to vary in response to the changing sea ice cover, and analysing the response of biology and biogeochemistry to these induced changes in present versus future environments (e.g., ocean acidification, warming). We will use existing complementary data sets provided by international project partners to achieve a wider spatial and temporal coverage of different parts of the Arctic Ocean. The unique combination of expertise (microbiologists, geochemists, ecologists, modellers) and facilities across eight leading UK research institutions will allow us to make new links between the quantity and quality of exported OM as a food source for benthic ecosystems, the response of the biodiversity and ecosystem functioning across the full spectrum of benthic organisms, and the effects on the partitioning of carbon and nutrients between recycled and buried pools. To link the benthic sub-system to the Arctic Ocean as a whole, we will establish close links with complementary projects studying biogeochemical processes in the water column, benthic environment (and their interactions) and across the land-ocean transition. This will provide the combined data sets and process understanding, as well as novel, numerically efficient upscaling tools, required to develop predictive models (e.g., MEDUSA) that allow for a quantitative inclusion seafloor into environmental predictions of the changing Arctic Ocean.