The rate of climate warming in the Arctic is among the most rapid on the planet, with dramatic effects upon ice, atmosphere and oceans of the region. Loss of sea ice is one of the most striking effects of warming, and an ice-free summer Arctic Ocean is predicted within a few decades. Sea ice margins are a highly productive habitat and its loss has profound influences on Arctic food-webs.
The retreat of sea ice also opens the Arctic up to fisheries, shipping and oil exploration which may further threaten biodiversity. Intrusion of Atlantic water northwards has resulted in temperate plankton and fish species extending their range into Arctic waters which has altered food-webs. As the "nearest neighbours" of the Arctic states, the UK and Germany have a particular interest in understanding the risks and opportunities that these changes in the Arctic Ocean may present. Accordingly, NERC launched the Changing Arctic Ocean programme to better understand impacts of warming upon Arctic marine food-webs. This resulted in funding of four excellent research projects that address the effects of climate change upon Arctic ecosystems, but significant gaps remain, including that of characterising the linkages of fish and seabirds to the wider Arctic food-web. Seabirds play a significant role in the functioning of food-webs, have considerable economic and cultural value and deliver important ecosystem services in the Arctic. Climate change is expected to have significant impacts on seabird habitats in the Arctic. The sea ice margin is highly productive and forms an important foraging habitat for seabirds. Its retreat away from their land-based breeding colonies can cause switching to other habitats, including meltwater plumes from glaciers, frontal zones or upwellings over bathymetric features which may be less productive for foraging. The range expansion of southerly species into the Arctic may further affect predator, prey and competitive interactions, thus increasing Arctic species’ sensitivity to warming. All these processes are likely to alter Arctic food-webs and populations of seabirds that depend upon them. Indeed, many Arctic seabird species populations are in decline in response to ocean warming. This project focuses on two closely related guillemot species: Brünnich’s (an Arctic species) and common (a temperate one) which comprise over half of the seabird biomass in the north Atlantic. The study will be conducted in Iceland which represents an "Arctic in miniature" owing to complex current flows from Polar, sub-Arctic and temperate water masses meeting around the coast and creating dramatic spatial gradients in oceanography and sea ice conditions within a relatively small area. A warming event over the past decade has altered fish distributions and adversely affected seabird breeding success and population trends. We will examine variation in habitat use and food-webs links of, and competition among, the two species of guillemot across these gradients in environmental variability and quantify the response of colony size to habitat availability. To achieve this we have assembled an international team who are world-leaders in the latest techniques in wildlife telemetry, stable isotope analysis and ecological modelling. Our project will improve our understanding of Arctic seabird habitat use, marine distribution and diets which will help to inform evidence-based conservation strategies, including marine spatial planning and ecologically sensitive fisheries management. We have formulated a broad and detailed impact plan to ensure the projects findings achieve policy and management outcomes, as well as reaching a wider public audience.