Chronobiology of changing Arctic Sea Ecosystems (CHASE)

理性：CHASE项目将通过了解和预测重要生态物种对气候变化的反应，实现NERC北冰洋变化项目的核心目标。随着北冰洋变暖，桡足类和磷虾等浮游动物的栖息地范围正在向两极扩展。这将导致它们暴露在高纬度地区新的、更极端的日长（光周期）气候中——已知许多陆生物种对适应性有负面影响。因此，我们将致力于研究桡足类和磷虾对其自然和新的光周期环境的行为，生理和遗传反应。我们将重点关注昼夜节律生物钟，它是昼夜长度测量和协调关键季节性生命周期事件的核心。方法：为了理解大尺度生态系统对气候变化的响应，我们需要从机制上理解驱动海洋生态系统及其功能生物多样性的关键生物的小尺度个体响应。个体间的高变异性是种群对变化条件的高适应能力的一个指标。由于关键物种的生态相关性，它们的个体变异可以指示未来生态系统的变化。我们的研究方法主要集中在北极的两个主要浮游动物群Calanus finmarchicus / Calanus glacialis （calanoid桡足动物）和Thysanoessa inermis（磷虾）。我们将：1)北极光气候（光谱、辐照度）的纬度和季节特征；2)确定个体桡足类和磷虾的行为表型与纬度和季节的关系；3)研究光周期对桡足类昆虫滞育的影响；4)确定行为表型的代谢状态（如上所述）；5)提供基因表达的季节性特征，重点关注时钟机制和光的影响；6)提供具有特定生命周期事件、代谢过程和环境条件特征的指示基因，以及基因计时；7)研究光和遗传时钟机制对季节时序的影响，以及这些因素如何与其他环境和生理因素协同作用；8)将这些数据整合到生命周期模型中，为这项工作提供一个更广泛的预测框架。我们将结合一种新颖但经过测试的方法，对桡足类动物和磷虾的活动进行大规模行为筛选，并对适应性进行经典的生理调查。采用果蝇生物钟研究的活动筛选方法，揭示果蝇的行为周期和节律，以及这些周期/节律在不同光周期下的变化。我们还将使用最先进的遗传分析来描述季节性生理变化的遗传特征，以及光如何调节生物钟和生物钟相关基因。最后，我们将把行为、环境和生理状态纳入现有的经过充分验证的基于个体的模型和动态优化模型中，以确定未来北极气候变化情景的预测适应成本。应用和效益：北极生态系统的平衡功能依赖于影响从鱼类到鲸鱼等所有较高营养水平的主要浮游动物消费者的成功。CHASE旨在了解这些关键生物如何在这种极端环境中发挥作用，并将开发必要的预测工具，以评估气候变化将如何影响未来的种群。这将通过一项综合抽样/实验/模拟方案来实现，从而为未来的科学方向提供信息，这对于帮助管理正在迅速变得越来越容易进行资源开发的地区至关重要。该项目嵌入了以英国、挪威和德国为基地的国际北极科学网络，并将在资助的生命周期之后留下合作的遗产。

Rational: The CHASE programme will address the core objective of the NERC Changing Arctic Ocean Program by seeking to understand and predict how ecologically important species will respond to climate change. As the Arctic Ocean is warming, zooplankton such as copepods and krill are undergoing habitat range extensions polewards. This will result in exposure to new and more extreme day-length (photoperiodic) climates of the higher latitudes - known in many terrestrial species to have negative consequences on fitness. We will therefore aim to investigate the behaviour, physiology and genetic responses of copepods and krill to their natural and new photoperiodic environments. We will focus on the circadian biological clock, central in day-length measurement and in orchestrating key seasonal life-cycle events.Approach: To understand large scale ecosystem responses to climate change we need to mechanistically understand small scale individual responses of key organisms driving marine ecosystems and their functional biodiversity. High variability between individuals is an indicator for high adaptive capacity of the population to changing conditions. Due to the ecological relevance of key species their individual variability can give an indication of future ecosystem shifts.Our approach focusses on the two Arctic key zooplankton groups Calanus finmarchicus / Calanus glacialis (calanoid copepod) and Thysanoessa inermis (krill). We will: 1) characterize the Arctic light climate (spectrum, irradiance) with latitude and season; 2) determine individual copepod and krill behavioural phenotypes with latitude and season; 3) investigate photoperiod as a diapause trigger in copepods; 4) determine the metabolic status of behavioural phenotypes (identified above); 5) provide seasonal characterization of gene expression with a focus on clock mechanisms and the influence of light and; 6) provide indicator genes characteristic for specific life-cycle events, metabolic processes and environmental conditions as well as genetic timekeeping; 7) investigate the effects of light and genetic clock mechanisms on seasonal timing and how the factors may synergistically interact with other environmental and physiological factors and; 8) incorporate these data into life-cycle models to provide a wider, predictive framework for this work.We will combine a novel, but tested, approach to large scale behavioural screening of activity in copepods and krill with classical physiological investigations on fitness. Activity screening methodology adopted from Drosophila clock research will reveal diel behavioural cycles and rhythms as well as the change of these cycles/rhythms with different photoperiods. We will also use state-of-the-art genetic analyses to characterise the genetic traits of seasonal physiological changes and how light modulates circadian clock and clock related genes. Finally we will incorporate the behaviour, environment and physiological state into existing well-tested individual-based models and dynamic optimisation models to determine the predicted fitness costs of future Arctic climate change scenarios.Application and benefits: The balanced functioning of the Arctic ecosystem is reliant on the success of key zooplankton primary consumers which influence all higher trophic levels, from fish to whales. CHASE aims to understand how such key organisms function in this extreme environment and will develop the predictive tools necessary to assess how climate change will impact their populations in the future. This will be achieved through a combined sampling/experimental/modelling programme, thereby informing future scientific directions, critical in helping manage areas which are rapidly becoming more accessible to increasing resource exploitation. The project is embedded within international Arctic science networks based in the UK, Norway and Germany and will have a legacy of cooperation beyond the lifetime of the funding.