UNDERSTANDING ECOSYSTEM PROCESSES IN THE BERING SEA 2007–2013

Biophysical Moorings Fig. 1 TAKING MOTHER OCEAN’S PULSE FROM AFAR The Bering Sea shelf is a big decades-long records of important place. It is bigger than the state of ecosystem variables. California, with weather that chal- During the Bering Sea Project lenges even the saltiest seafarers. we discovered that water is less Ships provide the best platform sharply stratified in the north than for scientists to make most ocean the south because tides are weaker. measurements, but both funding This creates a stable layer above the and seasonal ice cover limit ship- bottom mixed layer and below the based research in the Bering Sea. surface mixed layer, which receives Scientists with the joint research sufficient light to support a sub- EcoFOCI maintains an array of four moorings on the program Ecosystems & Fisheries- surface phytoplankton bloom in southeastern Bering Sea Shelf (M2, M4, M5, M8). Oceanography Coordinated the north during summer. Summer M2 began the 19th year of observation in 2013. Investigations (EcoFOCI), have primary production can affect the used moored oceanographic productivity of the entire food instruments (“moorings”), like web. We discovered how the spring a stethoscope anchored to the phytoplankton bloom is affected by The Big Picture seafloor, to track the health of ice retreat, and that blooms occur Long-term biophysical moorings provide year-round measurements of the Bering Sea year-round since deeper below the surface in the the state of the Bering Sea, filling the 1995. These moorings provide gaps in knowledge between ship-based continued on page 2 observations. These measurements provide a foundation for understanding the mechanisms that drive this productive region. The Bering Sea Project provided the opportunity to look at targeted ecosystem questions about the physical, chemical, and biological changes in climate and ocean conditions in the context of this long-term data set. During the Bering Sea Project, we used data from these moorings to help answer questions about the differ- ences between the northern and southern Bering Sea, and if animals will be able to shift their ranges northward with climate warming; the difference between warm and cold years on the Bering Sea shelf and how the animals that live here are affected; and how the timing of the spring bloom Edward Cokelet Edward will affect everything from the smallest EcoFOCI scientist Scott McKeever removes sensitive equipment on the surface buoy of the M2 Mooring before plankton to the largest whales. bringing it onboard the ship.

BIOPHYSICAL MOORINGS A component of the BEST-BSIERP Bering Sea Project, funded by the National Science Foundation and the North Pacific Research Board with in-kind support from participants. north. We learned that the magni- world’s most commercially valuable Fig. 2 tudes of the spring and fall blooms fisheries. This cold, shallow sea is are related, and that the interval also extremely variable, so predict- between blooms can vary by up to ing changes in ocean conditions has two months. This length of time great value from economic, ecologi- between spring and fall blooms may cal, and public safety perspectives. affect the amount of production We continue to measure the vital (i.e., food) that reaches higher tro- signs of the Bering Sea to better phic levels, including fish, seabirds, understand how this ecosystem and whales. responds to change. The Bering Sea oscillates between periods of relative How We Did It warm and cold conditions (Figure EcoFOCI maintains an array of 3). Observing how the ecosystem four long-term biophysical moor- responds to warm periods (i.e., ings in the Bering Sea (Figure 1). 2000-2005) vs. cold periods (i.e., Each mooring hosts instruments 2006-2010) can help us predict that make hourly measurements how this ecosystem responds to of temperature, salinity, nitrate, climate warming. This information chlorophyll (fluorescence), currents, will help us adapt to a changing and sea ice, year-round (Figure 2). climate and ensure that the living The instruments are programmed marine resources of the Bering Sea to take measurements at least every continue to be managed in a sus- hour and then store the data. The tainable way. M2 mooring also hosts acoustic Lisa Sheffield Guy, University of Washington Joint Institute for instruments that record zooplank- the Study of the Atmosphere and Ocean ton size and abundance and marine Phyllis J. Stabeno, National Oceanic and Atmospheric mammal vocalizations. Moorings Administration (NOAA) Pacific Marine Environmental Laboratory Jeffrey Napp, NOAA Alaska Fisheries Science Center are recovered and re-deployed using ships in spring and fall, weather and ice permitting. The Bering Sea Project is a partnership between the North Pacific Research Board’s Bering Sea Integrated Ecosystem Research Project and the Why We Did It National Science Foundation’s Bering Ecosystem The Bering Sea supports abun- Study. www.nprb.org/beringseaproject dant and diverse wildlife, coastal communities, and some of the Diagram of a biophysical mooring including surface buoy (ice-free seasons), illustrating how instruments Fig. 3 are arranged along the length of the mooring.

Temperature averaged across all depths mea- sured by the M2 mooring during 1995-2011.

BIOPHYSICAL MOORINGS A component of the BEST-BSIERP Bering Sea Project, funded by the National Science Foundation and the North Pacific Research Board with in-kind support from participants.