Arctic Integrated Ecosystem Research Program

ARCTIC INTEGRATED ECOSYSTEM RESEARCH PROGRAM

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All photographs unless otherwise noted are by Brendan Smith/NPRB.

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The waters surrounding Alaska are warming. Sea ice is thinning. Open water lasts longer. How is the ecosystem responding to these changes? What might the consequences be for Alaska commu- nities, especially with respect to food security? Such observations and questions led to the Arctic Integrated Ecosystem Research Program (Arctic IERP www.nprb.org/arctic-program). The program has focused on building a better understanding of how physical changes in the ocean influence the flow of energy through the marine food web in the Bering Strait, Chukchi Sea, and western Beaufort Sea. Since the program began in 2016, change has become even more rapid. The research leverages previous studies and collaborations with ongoing Arctic research and includes Arctic residents who contribute traditional and Indigenous knowledge to improve our understanding of how changes in sea ice and oceanography affect plankton, fishes, benthic invertebrates, seabirds, marine mammals, and coastal communities.

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Here, we report some of the major findings of our research. Background information and an outline of next steps follow.

The Chukchi Sea is warming Water temperatures in July to October in recent years were nearly 3 ºC (5 ºF) warmer than the average temperature for these same months in the early 1970s. Water from the Bering Sea flows northward into the Chukchi and Beaufort Seas. Ocean currents from the North Pacific have recently carried extra heat onto the Bering Sea continental shelf each year, reducing local sea ice extent and duration. Early ice retreat causes the ocean to absorb extra sunlight energy in the spring, leading to a warmer- than-normal ocean in summer and fall. Increasing northward flow at Bering Strait is mirrored by an increase of flow northward through Barrow Canyon into the Beaufort Sea. At least 50% more heat is subsequently available for melting ice and warming the waters of the Arctic Ocean. For example, there is enough excess heat exiting the Chukchi Sea through Barrow Canyon to warm the upper 100 m (300 ft) of the entire Beaufort Sea by roughly 0.5 °C (0.9°F).

Warming oceans are warming the Arctic atmosphere As Chukchi Sea waters have warmed, more heat is now released back to the atmosphere in autumn (about 30% more), making the Chukchi Sea an important contributor to warming Arctic air temperatures. Warming waters inhibit sea ice growth In fall, the excess heat gained by the ocean over the spring and summer must be lost back to the atmosphere before sea ice can form. Warmer waters in recent years have delayed fall ice growth by many weeks. South winds during winter contribute to early spring ice retreat Increasingly, winds are blowing from the south during winter, driving the sea ice and warm ocean water northward and contributing to early spring ice retreat.

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Nutrient availability varies widely year-to-year, influencing the base of the food web Marine productivity depends on nutrients, particularly the availability of nitrate. In the Chukchi Sea, ocean currents bring the nitrate northwards from the Bering Sea. The amount of nitrate can vary from year to year by as much as 50%. The nitrate in turn determines how much phytoplankton can grow. Phytoplankton are the base of the food web, supporting all the other species that live in the Chukchi Sea. Recent warming alters phytoplankton community structure, distribution and growth Arctic ocean warming and shorter periods of sea ice cover have altered the timing, distribution, composi- tion and nutritional quality of phytoplankton, which form the base of the food web. Multi-year periods of warmer-than-average conditions alter the seasonal phytoplankton succession pattern from diatoms in spring to smaller phytoplankton in late summer/fall. Such changes in phytoplankton communities influ- ence the diet quality and quantity for zooplankton and benthic invertebrates, including availability of omega-3 fatty acids that are higher in spring than late summer. This new information will be used to better understand potential changes in energy and nutrition transfer to other organisms in the food web in the northern Bering and Chukchi Seas.

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Warmer water means smaller, less nutritious zooplankton Zooplankton are the important food items that link phytoplankton with organisms higher in the food web. Some species of zooplankton accumulate large fat reserves that they use to overwinter, and these species are important prey items for juve- nile fishes, seabirds, and marine mammals. During spring, zooplankton are growing and reproducing at nearly their maximum rate. In the warm years of the IERP surveys, fewer large, fat-rich zooplankton were found during late summer compared to earlier in the decade. Zooplankton communities comprised of smaller zooplankton were influenced by increased transport of warmer Bering Sea water and plankton through the Bering Strait, particularly in 2019. These smaller zooplankton are less nutritious prey, having less overall caloric and fat content. Further warming will likely result in the increased importance of smaller zooplankton in Arctic waters as a food item for larger animals.

Harmful algal blooms are likely to increase

Warmer waters will likely increase the frequency and impacts of harmful algal bloom events, with potential ramifications for ecosystem and public health, including subsistence harvesting activi- ties. Large aggregations of dormant phytoplankton cysts known to be associated with harmful algal bloom (HAB) species, specifically the dinoflagellate Alexandrium spp., exist on the seafloor, with active cells observed in overlying waters near Icy Cape in the Chukchi Sea. Toxins from Alexandrium spp. and the diatom Pseudo-nitzschia spp. have been found in zooplankton, seabirds, marine mammals, and benthic invertebrates in this region. Research in this area is expanding and the Alaska Harmful Algal Bloom Network is serving a coordination role.

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The Chukchi Sea floor continues to be rich and productive… Large amounts of organic matter continue to sink to the seafloor, and support high productivity in benthic communities. However, the composition of this material is changing, with possible nutritional consequences for organisms that live on or feed at the seafloor. Particulate organic matter that falls to the seafloor (including ice algae, dead phytoplankton, and zooplankton fecal pellets) provides nutrition that sustains bottom-dwelling organisms. For example, as ice begins to melt in spring, algae living on the under- side of the ice fall to the seafloor. The Chukchi Sea is shallow enough that sunlight can reach the bottom, and detached ice algae can continue to photosyn- thesize there. Fecal pellets from zooplankton also rapidly settle to the seafloor. Initially, we thought that changes in sea ice and water temperature would increase consumption by zooplankton and fishes and prevent as much organic matter from reaching the seafloor. Instead we found that large amounts of organic matter continued to reach the seafloor.

… but changes are already occurring Changing food sources may contribute to shifts in the dominant species on the seafloor, and this has already been observed in some areas. Important prey items such as clams and amphipods have widely different needs in terms of caloric intake. Changes in the species that comprise benthic communities will impact how rapidly organic material is consumed in sediments and will have implications for the seabirds and marine mammals that rely on them. By 2100, some bottom-dwelling animals may find themselves in waters that are warmer than they prefer and perhaps even warmer than they can survive. As water temperatures warm, the metabolism and food consumption of animals on the seafloor will likely increase significantly, potentially resulting in food limitation for some species. These animals include the prey for bottom-feeding whales, seals and walruses, seabirds, and benthic fishes. Larger- bodied prey items like some clams may be replaced by smaller animals with reduced energy demands. Snow crab will likely benefit from warmer bottom sea temperatures.

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Warmer waters and swifter northward currents changed fish communities in the Chukchi Sea Rising summer sea temperatures were associated with an increased presence of warmer-water larval fishes in Arctic habitats historically occupied by colder water fishes. The larvae of many Arctic fish species experienced declines in abundance during recent warm years (2017-2019) that were also characterized by increased advection of waters from the south and a reduction in sea ice. During 2017, young Arctic cod were highly abundant over the Chukchi shelf, but in 2019, they were restricted to only the northeastern Chukchi Sea, likely due to increased northward flow of warm water from the Bering Sea. Large numbers of young walleye pollock were present in the Chukchi Sea in 2017-2019, and young Pacific cod inhabited the eastern Chukchi Sea during recent warm summers. Adult Pacific cod were also present in low densities in the western Chukchi Sea during the recent warm period. The presence of age-1 Pacific cod in the eastern Chukchi Sea may indicate that young Pacific cod are surviving through the winter. Changes in fish communities will impact the food web of the Chukchi Sea. Salmon, whitefish, herring, and sand lance have the highest caloric content of

fish in the Chukchi Sea, but they are not particularly abundant or widespread, and some of them are only seasonally available. Arctic cod have slightly more than half the caloric content of salmon, but because they are the most abundant Arctic fish species, they are crucial prey for many predators. Capelin are nearly as calorie-rich as Arctic cod, but large fluctuations in their abundance make them less dependable prey. A comparison of the fat storage in young Arctic cod from the summer of 2017 showed that they had only half the fat storage relative to that measured in fish from earlier colder years (i.e., 2013). The use of chemical biomarkers as well as stomach diet analyses indicate that reduced Arctic cod fat storage is linked to a dietary decrease of large fatty zooplankton. When sea ice is absent, young fish feed on lower quality prey items that originate from warmer waters from the south. If lower-fat fish such as walleye pollock or Pacific cod displace Arctic cod as ocean temp- eratures rise, their lower caloric content will require predators to consume more fish to meet their energy needs. Arctic cod likely spawn in the northern Bering and southern Chukchi seas, hatch in winter and spring, and grow in the Chukchi Sea over the summer.

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Previous surveys found very high abundances of young Arctic cod on the northeast Chukchi Sea shelf, suggesting that this region is a nursery area for young fish during summer. Relatively few adult Arctic cod have been found during research surveys on the Chukchi Sea shelf during summer months, leading to questions about when and where they spawn. Arctic cod from multiple spawning times and loca- tions, likely including areas in the northern Bering Sea, Bering Strait region, and Kotzebue Sound, hatch over an extended period from November into June and are carried into the northeast Chukchi Sea by currents. They appear to remain in the Chukchi Sea during summer where they feed and grow, and are then transported northwards to the Arctic shelf break in fall. These fish are distinct from spawning popula- tions in the Eastern Beaufort Sea based on multiple lines of evidence, including differences in hatch date distributions and otolith chemistry. In the southern Chukchi Sea, adult Arctic cod were scarce near the seafloor in June 2017 & 2018. However, Arctic cod are more abundant in the same area in the summer, suggesting that adult Arctic cod could be migrating from the north where food is abundant, to the south where they may spawn. In the Beaufort Sea in the summer, young Arctic cod are grouped into east and west populations. Those groups become less distinct as fish grow in size and swimming ability.

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The Chukchi Sea Ecosystem

Original Northern Chukchi Sea ecosystem painting collaboratively developed by artist Klara Maisch and Seth Danielson, Claudine Hauri and Andrew McDonnell. Additions to the original implemented by the Arctic IERP science team and artist Molly Trainor.

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Pink salmon are becoming more common as summer sea temperatures warm Higher numbers of pink salmon in the northern Bering Sea are contributing to higher numbers of adult pink salmon straying into coastal areas of the Chukchi and Beaufort seas. Some seabird species moved northwards in 2017-2019 when water temperatures were warmer Recent loss of sea ice and warmer ocean tempera- tures could impact seabirds directly (due to lack of prey or lower quality prey) and indirectly (if low-quality zooplankton reduces forage fish avail- ability). During the warm years of 2017-2019, some seabird species shifted northward from the northern Bering Sea into the Chukchi Sea (e.g., thick-billed murres and short-tailed shearwaters). Others, such as the least and crested auklets, that eat zooplankton, remained in the northern Bering Sea following failed breeding seasons in those years. A few species (e.g., common murre) continued to decline in abundance, which began around 2014. Murres and auklets, used by subsistence communi- ties, experienced unusual reproductive failure during warm years, particularly 2018 and 2019. The observed shifts in seabird distribution, along with low seabird reproductive success, may affect subsistence harvesters of seabird eggs and adults.

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Unusual seabird die-offs were observed in 2017-2019 in the Bering Strait Region

The nutrient-rich Anadyr Current to the north and west of St. Lawrence Island had more overall marine mammal detections and more diversity of marine mammals than did the region to the east of St. Lawrence Island. Coastal residents have experienced reduced food security More strong winds and storms, plus the more rapid spring break-up of sea ice, have reduced the duration of good hunting conditions available for many coastal communities to pursue the harvest of marine mammals. The timing of marine mammal migrations has shifted and increased commercial ship traffic has sometimes made marine mammals wary and harder to hunt. In some instances, however, later freeze-up and earlier break-up of sea ice have created new hunting opportunities, such as fall and winter whaling on St. Lawrence Island. Hanasaki crabs are now common around St. Lawrence Island, where they are now harvested as food. Salmon have become more common around Utqiaġvik, where they may displace the whitefish that many people prefer to catch. Additionally, more rain in summer has made it harder to dry meat and fish via traditional methods, often resulting in more spoilage. Warmer weather has led to flooding of some ice cellars and loss of stored food, as well as the inability to continue using this traditional storage methods in many locations.

Several species of seabirds were affected, including some that eat zooplankton (like the auklets) and others that consume fishes (primarily murres and shearwaters and smaller numbers of other species). The proximate cause of death of examined birds was starvation, but some birds that died in 2018 had levels of saxitoxin that have previously been associated with large die-offs, so the potential influence of harmful algal blooms cannot be discounted. Subarctic marine mammals stayed in the Arctic through the fall and early winter Hydrophones that listen for marine mammal calls detected subarctic species like humpback, killer, and fin whales from June to late November/early December. These species were often recorded at the same time as Arctic species such as bowhead whales and belugas. They may compete for food with Arctic animals and the presence of killer whales suggests that these predators are common in winter. During winter months, Arctic marine mammals including walrus, bearded seals, bowhead and beluga whales were commonly recorded throughout the study area, but especially to the north and west of St. Lawrence Island. We recorded ribbon seals less often.

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How people respond to change will help determine effects on coastal communities Coastal communities in the northern Bering and Chukchi seas are experiencing rapid societal and environmental changes. In addition to the ecosystem changes mentioned above, traditional hunting, fishing, and gathering are affected by government regulations, industrial development, limited financial resources, technology, and more. We found that all forms of change interact with one another to affect food security and community well-being. People respond to these changes in many ways, including shifting hunting practices, times, and locations, as well as innovating with new tools and techniques. Some practices and values, such as being prepared and being persistent, remain important contributors to successfully responding to change.

The ability of Tribes and communities to make their own decisions is essen- tial to adapting to change With so much changing at the same time, people need to be able to respond quickly and to try new approaches. Waiting for decisions to be made else- where hampers Tribal sovereignty and flexibility. Meaningful and ongoing communication, collabora- tion, and cooperation between Tribes, communities, the broader research community, and state and federal agencies can contribute to improved under- standings of, and responses to, changes and their implications. Sharing information is important, as is respecting Tribal expertise and authority when it comes to determining what best suits Tribal commu- nities’ needs.

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Background Information About the Arctic IERP

Before any Arctic IERP research proposals were written, the North Pacific Research Board admin- istered an assessment, the Pacific Marine Arctic Regional Synthesis that applied $1.5M provided by Shell and ConocoPhillips to compile and synthe- size existing information about the ecosystem and inform research priorities. This assessment included community meetings in 2013 in Savoonga, Gambell, Kotzebue, Nome and Barrow (now Utqiaġvik), in which representatives from 17 communities between St. Lawrence Island in the Bering Sea and Barter Island in the Beaufort Sea participated. Results from the scientific assessment and input provided via the community meetings informed the creation of the Arctic IERP.

The Arctic IERP began in 2016 with funding from the North Pacific Research Board, the Collaborative Alaskan Arctic Studies Program (formerly the North Slope Borough/Shell Baseline Studies Program), the Bureau of Ocean Energy Management (BOEM), and the Office of Naval Research Marine Mammals and Biology Program. Generous in-kind support was contributed by the National Oceanic and Atmospheric Administration, the University of Alaska Fairbanks, the U.S. Fish & Wildlife Service, and the National Science Foundation.

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The program conducted vessel-based surveys during spring, summer, and fall in 2017, 2018, and 2019 in the northern Bering Sea, Chukchi Sea, and western Beaufort Sea. Late spring and early summer sampling occurred in 2017 and 2018 aboard the R/V Sikuliaq . Late summer and early fall sampling occurred in 2017 and 2019 aboard the R/V Ocean Starr . In addition to the vessel-based surveys, sub-surface moored sensors were deployed to gather biophysical information continuously from June 2017 to September 2019.

Along with the vessel based work, a team of Arctic residents and social scientists, including members from eight communities in the North Slope and Northwest Arctic Boroughs and the Bering Strait region, met several times during the project to assess and analyze Indigenous observations and experiences with various types of change occurring in the region from Savoonga to Utqiaġvik.

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Map of vessel Sikuliaq operations in June 2017 & 2018.

Map of vessel Ocean Starr operations in August-September 2017 & 2019.

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What’s Next?

Peer-reviewed publications produced by the Arctic IERP may be accessed via the NPRB Arctic IERP website, www.nprb.org/arctic-program. Data collected by the Arctic IERP will be publicly available by late summer 2021 via national data archives and a data discovery portal linked to the NPRB website. NPRB will invest in a synthesis 2022-2024 that will build upon the results of the Arctic IERP and NPRB has committed to funding a future IERP that will continue integrated research in the Bering and Chukchi Seas, centered in the northern Bering Sea. Areas of interest include how shifts in environ- mental conditions and processes may influence species of commercial, ecological and subsistence importance, and implications for state and federal fisheries management and communities that depend on these resources.

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www.nprb.org/arctic-program

For more information, contact:

Danielle Dickson Senior Program Manager/Chief Officer for Collaboration and Synthesis Danielle.Dickson@nprb.org

Matthew Baker Science Director Matthew.Baker@nprb.org

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