North Pacific Climate Regimes and Ecosystem Productivity Changing climate, changing ecosystem: Current issues & results

Alaska has one of the longest coastlines and largest areas of responsibility for integrated ecosystem assessments. The Alaska Ecosystem Complex comprises four of the world’s Large Marine Ecosystems: Gulf of Alaska, East Bering Sea, Chukchi Sea and Beaufort Sea. Ship time and research funding commitments need to scale to the area for effective execution of responsibilities.

IPCC Sea Ice Projections & Bering Sea Response The rate of Arctic sea ice loss is faster than the expected values from IPCC climate models. The paradigm is that the Arctic must freeze before the Bering Sea. With a delayed ice cover in the Arctic, it is expected that the Bering’s ice extent will also decrease significantly. Any decrease in ice extent will significantly warm the southern Bering Sea shelf, which will have implications for the whole ecosystem. Depth Averaged Temperature at M2 M2 62°N 58°N

Is the eastern Bering Sea shelf becoming more stratified? Summer: Calanus marshallae Napp, AFSC Stratification over the southern shelf is sharp. Increased solar energy flux and decreased wind energy are resulting in a more strongly stratified water column. It takes more energy to transport nutrients into the surface waters during summer, and there may be a reduction in the nutrient reservoir farther north. Important prey for forage fishes, seabirds, and marine mammals have declined in recent years. Moorings are a critical part of our observation system and provide a long time series of measurements for the eastern Bering Sea. Without a new infusion of funding for these sentinels by 2009, the moorings will be removed in 2010, and the time series will end. Coyle et al., DSR II, in press Simpson’s Stability Parameter (J m -3 ) 2004 BASIS: L. Eisner, AFSC MM Structure along the 70-m isobath, Sept Stabeno et. al.

Are localized areas of concentrated trophic transfer at risk? Some locations in the Bering Sea and Gulf of Alaska are more important than others for the transfer of energy up the food chain. Often these pulse points or “hot spots” exist because of unique interactions between current flow and bathymetry. If ocean currents are altered by changing gradients in saltiness and temperature, what will happen to these pulse points and the commercial and protected resources that rely on them?

Population distributions are changing with climate The eastern Bering Sea contains the faunal boundary between northern temperate species and arctic species. The position of this boundary is most likely the southern edge of the cold pool, which is formed by the southernmost extent of sea ice and modified by summer conditions. In years when sea ice is at a minimum, temperate species are potentially more successful at colonizing the area. With warming of the region, we expect to see more temperate species “invading” the eastern Bering Sea from the south. This will affect the existing productivity, food webs, predator-prey and host-parasite relationships that have existed for long periods of time. Ultimately, the system as we know it will change in response to the presence of new species and the absence of older, established species. Mueter & Litzow, 2008 Species Latitudinal displacement (km) Northward shift (km) in center of distribution of multiple species from Stabeno et al., in prep.

In Peril Steller Sea Lion Snow Crab Tanner Crab North Pacific Right Whale Walleye PollockRibbon Seal Pacific Walrus Polar Bear For 2008, the biomass of the EBS pollock population was estimated to be below its MSY level, and a proportional adjustment to harvest rate was necessary. The estimated ABC for 2008 was 13% lower than what was estimated last year due to about 4 or 5 years of below average recruitment. At the fall North Pacific Fisheries Management Council, the Plan Team recommended a lower TAC (1 MMT instead of ~1.4 MMT). This recommendation was reviewed in light of additional data supplied by NPCREP: warmer temperatures and lower zooplankton biomass, along with increasing predator abundance. These and other warning signs suggest a more cautious approach with fisheries. It is not just pollock, our country’s major fishery, that is showing decreases in abundance. All of the organisms on this page are under some sort of strain with the recent warming.

NOAA takes pride in being a good science partner, working with other entities on national science issues. The eastern Bering Sea is currently the focus of a concentrated effort by NSF and NPRB to understand how climate change and loss of sea ice are affecting the ecosystem. Unfortunately, websites like this don’t tell the whole story. Of the 93 scientists involved, 30 are NOAA researchers who bring their expertise, their salaries and their ship time to the project with the blessings of their leaders. The success of the Bering Sea Integrated Ecosystem Research Program clearly is dependent on adequate NOAA base and Goal Team funding.

As the cold seas warm, scientists plunge in to find where the fishes go. Bering Sea haiku Nora Deans BEST-BSIERP Outreach Manager