Can we detect changes in Arctic ecosystems?

生态系统是相互作用并与环境相互作用的生物群落。它们通常被认为是食物网或食物链，描述了不同生物体之间的相互作用及其相对等级，称为营养位置。海洋生态系统提供关键服务，如营养、控制气候、支持养分循环，并对某些社区具有文化意义。因此，我们必须了解环境变化如何重塑生态系统，以便管理气候变化的影响。北冰洋已经受到气候变化的严重影响。它比任何其他海洋区域变暖都快，随着它吸收化石燃料排放，它正在逐渐酸化。北极海冰每十年减少10%。这影响了从浮游生物到哺乳动物的海冰栖息地的可用性，并改变了海洋环境。最后，北极还受到太平洋和大西洋之间水的流动规模以及这些沃茨组成的变化的影响。因此，北极生态系统正在受到多种并发压力的影响，必须适应。为了了解北极生态系统将如何应对多种压力，评估持续变化的影响至关重要。这些问题通常通过研究来解决，这些研究侧重于一个地方的特定生态系统，并记录了食物链的各个组成部分。然而，北极是多样化的，有各种各样的环境，对独特的压力源有不同的反应。我们需要一种新的方法，能够从泛北极的角度提供关于北极生态系统的十年时间尺度的信息。要有效监测泛北极生态系统的变化，就需要有侧重于关键生态系统组成部分的示踪剂，并提供关于生态系统结构的定量信息，为管理和保护生态系统服务提供信息。我们的目标是应对这一挑战。我们将同时关注食物链的基础，由海洋浮游植物的活动控制，以及关键的北极捕食者，竖琴和环斑海豹。海豹是监测食物网的绝佳候选者，因为它们的泛北极分布和觅食行为，这意味着它们暴露在不断变化的环境中。氮和碳的稳定同位素经常被用来检查生态系统，因为它们在食物链的营养转移过程中发生了变化。因此，他们可以量化海豹的营养地位和食物链长度，生态系统结构的关键决定因素。然而，在这方面至关重要的是食物网基础的同位素值，称为isoscape，它本身受到一系列环境特征的影响，并在空间和时间上波动。同样，由于迁移模式的改变，海豹本身可能以不同等壳纲中的类似猎物为食，这将影响从稳定同位素对生态系统结构的解释。这些都是使用稳定同位素的主要挑战。我们将把稳定同位素与食物网的新型示踪剂（称为生物标志物）联系起来。当这些示踪剂进行比较，对观察到的移动isoscape和海豹觅食的数据，他们允许海豹被用来监测北极生态系统，量化其营养位置和整体食物链长度。通过一系列观测平台，我们的新食物网示踪剂将与北极等尺度和海豹行为的空间和季节趋势机械地联系起来。通过将北极盆地周围的历史观测与最先进的海洋和海豹种群建模相结合，我们可以量化北极生态系统过去和未来的变化。这将提供有关北极生态系统过去变化的信息，但也将制定一种可用于监测未来变化的方法，并有助于管理和保护生态系统服务。

Ecosystems are communities of organisms that interact with each other and their environment. They are often considered in terms of food webs or chains, which describe the interactions between different organisms and their relative hierarchies, known as trophic position. Ocean ecosystems provide key services, such as nutrition, control of climate, support of nutrient cycling and have cultural significance for certain communities. It is thus important that we understand how changes to the environment reshape ecosystems in order to manage climate change impacts.The Arctic Ocean is already being heavily impacted by climate change. It is warming faster than any other ocean region and as it absorbs fossil fuel emissions, it is gradually acidifying. Arctic sea ice is declining by 10% per decade. This affects the availability of sea ice habitats for organisms from plankton to mammals and modifies the ocean environment. Finally, the Arctic is affected by changes in the magnitude of water movement to and from the Pacific and Atlantic Oceans and composition of these waters. Thus Arctic ecosystems are being impacted by multiple concurrent stressors and must adapt. To understand how Arctic ecosystems will evolve in response to multiple stressors, it is crucial to evaluate the effects of on going change. Often these questions are tackled by studies that focus on a specific ecosystem in one location and document the various components of the food chain. However the Arctic is diverse, with a wide range of environments that are responding to unique stressors differently. We require a new approach that can provide information on Arctic ecosystems from a pan-Arctic perspective over decadal timescales. To effectively monitor changes to pan-Arctic ecosystems requires tracers that focus on key ecosystem components and provide quantitative information on ecosystem structure, providing information for management and conservation of ecosystem services. Our goal is to respond to this challenge. We will focus simultaneously on the base of the food chain, controlled by the activity of marine phytoplankton, and key Arctic predators, harp and ringed seals. Seals are excellent candidates to monitor the food web due to their pan-Arctic distribution and foraging behaviour, which means they are exposed to the changing environment. Nitrogen and carbon stable isotopes are often used to examine ecosystems as they are modified during trophic transfer up the food chain. Hence, they can quantify seal trophic position and food chain length, key determinants of ecosystem structure. Crucial in this context however is the isotope value of the base of the food web, known as the isoscape, which is itself affected by a range of environmental characteristics and fluctuates in space and time. Equally, by virtue of changing migration patterns, seals themselves may feed on similar prey in different isoscapes, which would affect the interpretation of ecosystem structure from stable isotopes. These are the major challenges in using stable isotopes.We will link stable isotopes to novel tracers of the food web, known as biomarkers. When these tracers are compared against observations of the shifting isoscape and data on seal foraging, they permit seals to be used to monitor the Arctic ecosystem by quantifying their trophic position and overall food chain length. Via a range of observational platforms, our new food web tracers will be mechanistically linked to the spatial and seasonal trends in the Arctic isoscape and seal behaviour. By then combining historical observations from around the Arctic basin with state of the art ocean and seal population modelling, we can quantify past and future changes in Arctic ecosystems. This will provide information on past changes to Arctic ecosystems, but also put in place an approach that can be used to monitor future changes and aid in the management and conservation of ecosystem services.