The future of Arctic coastal ecosystems 

Glaciers and sea ice are declining, impacting marine biodiversity, ecosystem functioning, tourism and Arctic livelihoods. Here we present some results from the EU-funded research project FACE-IT: The Future of Arctic Coastal Ecosystems–Identifying Transitions in fjord systems and adjacent coastal areas.

Arctic fjords are changing rapidly. A warmer climate has been the major driver. But other factors also put pressure on the natural environment, including fishing, tourism, and changes in socioeconomic conditions. FACE-IT studied changes in marine biodiversity, ecosystem functioning and consequences of global warming for Arctic societies. The aim was to enable adaptive co-management of changing social-ecological fjord systems. FACE-IT compared Arctic fjord systems at different stages of cryosphere loss in Greenland, Svalbard, and Porsangerfjord (Finnmark). In this article, we present results from Svalbard and focus on Atlantification. 

The fjords in western Svalbard are receiving an increased, but variable inflow of warm Atlantic Water from the West Spitsbergen Current. FACE-IT has facilitated publication of hydrographic data collected from Kongsfjorden by the Norwegian Polar Institute, extending previously published timeseries from annual cruises up until 2020, after which seasonal hydrographic measurements in the fjord were started. It is important to monitor conditions to detect changes and understand their connection with changes in sea ice, marine-terminating glacier fronts, and species distributions. 

Sea ice in Svalbard fjords is an important driver of local and regional climate, affecting energy exchange between the atmosphere and the ocean; it is also a habitat for species such as ringed seals and ice algae. Long-term monitoring of sea ice in selected Svalbard fjords covering several decades shows changes: a shorter sea ice season, less ice extent, thinner ice and less snow. The FACE-IT project helped Norwegian Polar Institute scientists collect and publish sea ice and glacier field data from Kongsfjorden, thereby promoting interdisciplinary scientific collaboration, including consequence modelling.

Tidewater glacier fronts in Kongsfjorden have been retreating since the late 1800s, with some short-term variability governed by calving and melting, and by glacier flow speed. Flow speed is controlled, in part, by long-term trends in mass balance, while calving and melting are affected by water temperature and subglacial topography. Another factor is glacier surging, in which a glacier switches from flowing at relatively slow speeds, over periods of many decades, to sudden short-duration, high-speed events that last only a few years.

The environmental changes in Arctic fjords, a result of warming, are affecting the plankton community. Boreal species have become more prominent, though glacial bays and sill fjords where the intrusion of warm Atlantic Water is restricted, are refugia where seasonal sea ice cover continues to persist. In these areas the abundance of boreal species is modest, because the long food-poor winter restricts their survival, and the community is reset to a purer Arctic state over the winter. A similar community re-set in winter is also recorded in warmer, ice-free fjords among single-celled organisms (protists), which have been studied monthly in Adventfjorden since 2011. A comprehensive comparison of the seasonal dynamics of phytoplankton blooms in three distinct Arctic fjords studied in FACE-IT—Nuup Kangerlua (Greenland), Ramfjorden (mainland Norway), and Adventfjorden (Svalbard)—showed pronounced spring blooms in all three fjords, but only Ramfjorden at 64°N and Nuup Kangerlua at 69°N had regular summer and autumn blooms.

A short primary production season constrains secondary production of boreal zooplankton in Svalbard (at ≥75 °N) and will likely continue to do so in the future since the solar angle is too low to support algal growth beyond mid-September. Sea temperatures will continue to increase with global warming and reduce zooplankton developmental time, potentially favouring boreal zooplankton over Arctic ones in the future. Seasonal zooplankton data from Isfjorden and Kongsfjorden confirm that the boreal Calanus finmarchicus has established local populations and occurs in similar or even higher numbers than its Arctic sibling species C. glacialis.

FACE-IT facilitated several studies that investigated how interannual variations in sea ice conditions impact Svalbard seabird survival, breeding success and body condition. Overall, these studies suggest that spring sea ice can affect the body condition and demography of Arctic seabirds, but does not play a major role. Effects of sea ice varied among species and with the different types of ice considered (e.g., drift vs fast ice). These results highlighted the importance of recognising the heterogeneous nature of sea ice habitats.

Changes in sea ice are generally expected to affect seabirds mostly via indirect effects on their prey. However, they might also affect seabirds via changes in predation. In Svalbard, common eiders generally breed on small islands. Sea ice in the spring can create bridges allowing predators such as Arctic foxes (Vulpes lagopus) to reach these islands and significantly reduce eider breeding success. The decline in sea ice has reduced the connectivity of islands to the mainland, decreasing predation risk. This has led to a redistribution of breeding eiders, with new colonies established on islands that have become safer following the retreat of spring sea ice. These results illustrate that complex and fine-scale changes in predator–prey interactions, driven by sea-ice loss, can reshape habitat suitability and influence Arctic wildlife dynamics.

All Arctic endemic marine mammals are strongly ice-associated. Arctic whales depend on sea ice for protection from storms and predators; Arctic seals give birth on sea ice and use it as a platform for resting and moulting. Polar bears travel extensively on sea ice to access their primary prey, which is ice-associated seals. A warming Arctic, with major reductions in sea ice poses a strong threat to Arctic endemic marine mammals. Studies conducted within FACE-IT have shown significant distributional changes over the last three decades for many marine mammal species. For example, boreal cetaceans have responded positively to the increases in Atlantic Water on the west coast of the archipelago, expanding into fjords and across the north of Spitsbergen. Similarly, the temperate harbour seal population has expanded its range dramatically over recent decades. Acoustics studies suggest that the bearded seal (Erignathus barbatus) has become less abundant in Kongsfjorden and now shows a seasonal mismatch between availability of sea-ice habitats and reproductive behaviour. FACE-IT also investigated the movement of walruses (Odobenus rosmarus), and found that they return faithfully, year after year, to summer haul-out sites in Svalbard and winter sites on sea ice east of the archipelago. Ongoing ice reductions will reduce habitat available for walruses in the Barents Region.