ARCTIC OCEAN SYNTHESIS: ANALYSIS OF CLIMATE CHANGE IMPACTS IN THE CHUKCHI AND BEAUFORT SEAS WITH STRATEGIES FOR FUTURE RESEARCH RUSS HOPCROFT, BODIL BLUHM, ROLF GRADINGER (EDITORS) INSTITUTE OF MARINE SCIENCES, UNIVERSITY OF ALASKA, FAIRBANKS DECEMBER 2008 1 Arctic Ocean Synthesis: Analysis of Climate Change Impacts in the Chukchi and Beaufort Seas with Strategies for Future Research Ian McDonald/ TAMU TABLE OF CONTENT INTRODUCTION ................................................................................................................................3 PHYSICAL OCEANOGRAPHY ............................................................................................................. 6 CHEMICAL OCEANOGRAPHY.......................................................................................................... 18 SEA ICE.......................................................................................................................................... 24 PHYTOPLANKTON (PRIMARY PRODUCTION) .................................................................................. 33 MICROBES...................................................................................................................................... 38 ZOOPLANKTON .............................................................................................................................. 45 BENTHOS ....................................................................................................................................... 56 FISH ............................................................................................................................................... 66 SEABIRDS....................................................................................................................................... 80 MARINE MAMMALS ....................................................................................................................... 88 REPORT SUMMARY ...................................................................................................................... 109 REFERENCES ................................................................................................................................ 113 2 INTRODUCTION There is now strong scientific evidence that the Arctic Ocean is changing, with a profound effect on this ecosystem and the way it will be utilized by humans (ACIA 2004, www.amap.no/acia). The most notable present physical trends are manifested in the temperature increase, the reduction of the total ice volume, and the extent of the sea ice (Fig. 1; Walsh 2008). Other changes in the physical environment in the Arctic shelf regions include increased river discharge, rising sea-level, thawing of permafrost and coastal erosion. Changes in albedo (light reflectance) associated with snow and sea-ice trends can result in a positive feed-back on warming trends, with record summer minimums observed most of this decade (Comiso et al. 2008) and projection that the Arctic could be ice-free during summer by 2060 (Walsh 2008). The potential biological impacts include shifts in species distributions, changes in the timing and magnitude of production cycles, risk to marine species dependent on sea-ice, and increased exposure of organisms to UV radiation through loss of snow and ice cover. Impacts on society are wide ranging and include changing access to traditional foods, loss of hunting cultures, expanded marine shipping, increased access to marine natural resources, and enhanced Arctic fisheries (ACIA 2004). The challenges at both the regional and Pan-Arctic scales are to take the global- scale generalizations on climate change plus the functioning of each biological realm (e.g. Gradinger 1995, Smith and Schnack-Schiel 1990), and refine them with the details to assess past, present and future patterns. The ecosystems of the Arctic Ocean and northern Bering Sea are less well known than most US oceanographic regions because of their remoteness and the extensive seasonal and permanent ice cover that interferes with physical and biological sampling efforts. Although investigations of Alaskan waters began in 1888 with the US Fisheries Bureau flagship Albatross, no hydrographic or biological sampling appears to have occurred north of Bering Strait at the time. For much of the last century, drifting ships (e.g., Nansen’s Fram) and ice stations (e.g., T3, ARLIS 1&2, Russian drift stations “North Pole”, NP-2, 3-5) were the only means of peering through the ice cover for much of the year. In contrast, there is a longer history of Fig. 1: Interannual changes in the minimum summer sea ice extent of Arctic sea ice: 1980 versus 2003 access to the shallower coastal seas that (http://science.hq.nasa.gov/directorate/04review.html) generally become ice-free for some period during the late summer months. Thus, for many oceanographic disciplines, seasonal observations are largely restricted to the basins, while the most spatially extensive observations are highly biased toward areas and periods where ice cover is minimal. 3 The Beaufort and Chukchi seas together represent the ‘Arctic’, one of Alaska’s 3 Large Marine Ecosystems (LME) as defined by NPRB. Large scientific programs in this LME and the adjacent sub-polar Bering Sea within the last three decades include the earlier Alaskan Outer Continental Shelf Environmental Assessment Program (OCSEAP) and the Inner Shelf Transfer and Recycling (ISHTAR) program, plus the more recent Surface Heat Budget of the Arctic Ocean (SHEBA) drift across the Chukchi Plateau, the 1994 Arctic Ocean Transect, the Shelf- Basin Interactions (SBI, http://sbi.utk.edu) program on the Beaufort and Chukchi Shelves, the Canadian Arctic Shelf Exchange Study (CASES; http://www.cases.quebec- ocean.ulaval.ca/welcome.asp), the Circumpolar Canadian Flaw Lead program (CFL- http://www.ipy-cfl.ca/) - cross-basin cruises by NOAA’s Ocean Exploration (OE) Program (http://www.oceanexplorer.noaa.gov/explorations/05arctic/welcome.html, http://www.oceanexplorer.noaa.gov/explorations/02arctic/welcome.html), and the Canadian/Japanese Joint Western Arctic Climate Study (JWACS). The more recent international Arctic shelf studies frequently contributed into the larger framework of the Shelf-Basin- Exchange (SBE) initiative of the Arctic Ocean Science Board (AOSB, www.aosb.org). Though extensive, results from many of these more recent programs are just beginning to appear in the scientific literature. What have remained problematic are the political boundary bisecting this region and access to the relevant Russian literature to complete our understanding of the dynamics of this region. Some relevant synthesis of the Russian literature has been conducted using data from Bering Strait southward (e.g. Coyle et al. 1996); but aside from compilations of species lists (e.g. Sirenko 2001), synthesis including Russian data is generally scarce from regions to the north of the Strait (e.g. Grebmeier 1993, Feder et al. 1994). Notable exceptions have been data from the five Joint US-USSR Bering Pacific (BERPAC) cruises executed between 1977 and 1993 (Tsyban 1999), and the Joint Russian-American Long-term Census of the Arctic (RUSALCA) cruises begun in 2004 (http://www.arctic.noaa.gov/aro/russian-american/). In addition to these co-ordinated efforts, a multitude of smaller research efforts funded by various government agencies (e.g. NSF, USGS, USFWS, NOAA, NPRB), as well as the oil and gas industry, have looked at individual components of the physical, chemical and biological aspects in less co- ordinated context amassing a considerable body work, most often directed toward fish, seabirds and marine mammals. The recent oil and gas exploration leases awarded in the Chukchi Sea are also expected to spur a new body of knowledge in the coming years. The recent changes in the sea ice regime have prompted concern that polar systems and their biological communities may be particularly sensitive to climate change (e.g. Sturm et al. 2003, Grebmeier et al. 2006a,b), in part because they are so highly adapted to the extremes of this environment (Pörtner and Playle 1998). For the Chukchi and Beaufort seas, ecosystem changes could be profound if changes in bentho-pelagic coupling lead to increased pelagic production and a reduction of benthic production (e.g. Grebmeier et al. 2006b). Such reorganization in the way the ecosystem operates will ultimately alter the pathways and magnitude of energy that passes into upper trophic levels such as fish, sea-birds and marine mammals, and impact the people dependent on those resources. Similar concerns for the sub- arctic Bering Sea stimulated a new research effort funded jointly by NSF and NPRB, which reaches from physical forcing to ecosystem and human impacts (http://bsierp.nprb.org/). There is, therefore, urgency to integrate and synthesize the present state of knowledge of the biology and oceanography of this region as required baseline information against which to 4 observe and understand ongoing changes. A multidisciplinary team was assembled at the University of Alaska Fairbanks, to undertake such an activity, specifically for the Chukchi and Beaufort seas and nearby waters, which are of particular interest to NPRB. We attempted to qualitatively synthesize past and present knowledge gained during research programs in the Chukchi and Beaufort seas by holding an interdisciplinary workshop in the spring of 2006 to bring together experts from the United States, Russia, Canada, and Japan. The goal of this