Explore the Science

Lead: Kerin Aydin and Ed Farley

We will provide biological and physical data on the food habits of groundfish relative to predator and prey fields. We will use this information to evaluate whether competition for common prey or predator avoidance influences the spatial and temporal distribution of forage fish. Understanding these processes will provide the information needed to build computer models to assess the potential impact of climate change on forage fish movement and seasonal distribution.

Lead: Anne Hollowed

Co-PIs: Kerim Aydin, Steve Barbeaux, Ned Cokelet, Alex DeRobertis, Stan Kotwicki, Patrick Ressler, Phyllis Stabeno, Chris Wilson

We will provide biological and physical data from a commercial fishing vessel, acoustic surveys and bottom trawl surveys. We will use this information to identify the processes influencing the spatial and temporal distribution of forage fish, their predators and competitors relative to ocean habitat conditions and to evaluate hypotheses regarding the potential impact of climate change on forage fish movement and seasonal distribution.

Lead: Ed Farley

The Alaska Fisheries Science Center conducts annual surface (epi-pelagic) trawl surveys to monitor the condition of the eastern Bering Sea continental shelf epi-pelagic fish community. This survey is funded with in-kind money and will support BEST-BSIERP by providing biological and environmental survey data to other PIs in the program.

Lead: Robert Lauth

The NOAA Alaska Fisheries Science Center conducts annual bottom (benthic) trawl surveys to monitor the condition of the eastern Bering Sea continental shelf epi-benthos. This survey is funded with in-kind money and will support BEST-BSIERP by providing biological and environmental survey data to other PIs in the program.

Lead: S. Bradley Moran

We will quantify the export flux of organic carbon in the Eastern Bering Sea water column. We will also link arbon export to primary production and benthic oxygen utilization to assess the efficiency of pelagic-benthic coupling associated wtih seasonal and interannual changes in sea ice extent.

Lead: Jacqueline Grebmeier

Co-PI: Lee Cooper

We will use a custom-built benthic digital imaging system at shallow stations in the Bering Sea. We will then analyze the imagery to determine grouping patterns of association between infaunal animals, bottom types and environmental factors.

Lead: Jacqueline Grebmeier

Co-PI: Lee Cooper

We will document benthic infaunal community composition and biomass as a means to determine key indicator species that should be monitored to evaluate climate change impacts on the Bering Sea ecosystem. In addition, they will analyze sediment indicators of status and trends in ecosystem health, including sediment grain size, oxygen demand, chlorophyll inventories, organic carbon content and stable carbon isotope ratios of sediment organic carbon. These can be used as ecosystem indicators of recent particle deposition, sediment processing, and the overall fertility of overlying waters.

Lead: S. Bradley Moran

Co-PI: Michael Lomas

We will investigate how the production and partitioning of spring bloom organic carbon, phytoplankton community structure, export, and water column-benthic coupling varies spatially (north-south) and temporally (seasonally and from year to year), as a function of sea ice extent. These spatial and temporal patterns are hypothesized to affect the lower trophic levels (primary producers and zooplankton) as well as upper-trophic organisms (fish, marine birds, mammals) exploited by commercial fisheries and subsistence hunters.

Leads: Ray Sambrotto, Dan Sigman

We will measure new (nitrate) and regenerated nitrogen product ion directly with tracer incubation measurements in ice-impacted and ice-free regions of the eastern Bering Sea shelf. This project also will measure the natural isotopic ratios of both the nitrate supply (both 15N/14N and 18O/16O) and the forms of nitrogen produced (the 15N/14N of suspended and sinking particles, dissolved organic N and ammonium). These measurements provide a passive isotope approach that will reflect the intensity of nitrate assimilation and provide a new constraint on shelf new product ion.

Leads: Allan Devol, David Shull

Denitrification in shelf sediments of the southeastern Bering Sea is estimated to remove about one third of the total nitrate supply to the Bering Shelf. We will measure profiles and fluxes of oxygen, nitrate, ammonium, phosphate and silicate. We will also collect samples for measurement of 222Rn and 210Pb profiles, from which we will calculate sediment bioirrigation rates and bulk sedimentation rates, respectively. This combination of measurements will allow us to estimate sedimentary denitrification rates, overall benthic carbon oxidation rates, macrobenthic irrigation rates and organic-matter burial rates.

Lead: Rolf Gradinger

Co-PIs: Bodil Bluhm, Katrin Iken

We will analyze spatial and temporal patterns of abundance, biomass, community composition and productivity of sea ice algae and phytoplankton just below the ice. We will measure salinity, temperature, and nutrient concentrations in ice cores and under-ice water, as well as ice thickness, snow cover and light regime. Sedimenting material, stable isotope ratios and algal community composition will be used as three lines of evidence to follow the fate of ice algal production through the pelagic and into the benthic food web of the Bering Sea. The combined data set will allow for a refined interpretation of the relevance of the sea ice produced organic matter for the food web structure in the Bering Sea.

Lead: Janet Duffy-Anderson

Co-PIs: Franz Mueter, Lisa Eisner, Ann Matarese, Jeff Napp

Successful recruitment of fish larvae to suitable juvenile nursery areas is a necessary condition for growth, energy storage, survival, and subsequently recruitment to adult populations. Climate variability, which may change existing meteorological and oceanographic conditions, will likely impact transport mechanisms between these areas. A better understanding of these transport pathways, larval behavior during the transport process, and delivery mechanisms (including settlement for flatfish) will help us predict the impact of changing climate conditions on recruitment success to adult populations.

Lead: Ron Heintz

Co-PIs: Tom Hurst, Ben Laurel

We will study how growth, energy storage and metabolism interact to regulate the distribution and abundance of walleye pollock, Pacific cod and arrowtooth flounder in the Bering Sea. In order to recruit as adults, juvenile fish must survive multiple periods of energy depletion, which increases their risk of predation, starvation and disease. We will build models that relate the energy phenology of juvenile pollock, Pacific cod and arrowtooth flounder to seasonal changes in their distribution and abundance.

Lead: Diane Stoecker

Microzooplankton do most of the “grazing” on phytoplankton in the Bering Sea and are an important link in the food web between phytoplankton and zooplankton, which are food for fish. Microzooplankton grazing also regulates phytoplankton blooms. This project will provide summer data on standing stocks of microzooplankton and their grazing activities. We will estimate abundance, biomass, size distribution, and composition of larger microzooplankton, and will measure grazing by microzooplankton on phytoplankton.

Leads: H. Rodger Harvey, Evelyn Lessard

We hypothesize that seasonal and interannual variation in the timing and coverage of sea-ice and associated food resources will lead to differences in age structure, diet history and nutritional condition for euphausids, which ultimately translate into differences in product ion rates and availability as prey to higher trophic levels. We will quantify the age structure and diet history of important euphausids together with detailed information on their consumption and growth. We will also link field collections and analysis with laboratory rearing for age calibrations and shipboard feeding experiments to test the validation and retention of trophic lipid markers, as well as the quality and quantity of food resources.

Leads: Evelyn Sherr, Carin Ashjian, Robert Campbell

Co-PI: Barry Sherr

We will analyze zooplankton (standing stock determinations and rate measurements) to determine relative microzooplankton and mesozooplankton grazing impacts. This project will provide size-fractioned chlorophyll-a concentrations as well as biomass stocks and rate measurements of grazing and growth for microzooplankton and mesozooplankton.

Lead: Ken Coyle

Co-PI: Alexei Pinchuk

We will assess mesozooplankton populations during the spring and summer cruises during the field seasons outlined for BEST-BSIERP. We will measure total primary production, measuring the carbon chlorophyll ratios of the phytoplankton taxa and assess species composition, biomass and abundance of the phytoplankton, microzooplankton, mesozooplankton and micronekton (euphausiids) on the eastern Bering Sea shelf.

Lead: Rolf Sonnerup

Co-PIs: Dean Stockwell, Terry Whitledge

We will collect, quality control, analyze and distribute the core chlorophyll-a data on databases at PMEL, NODC, and AOOS. We will also use the biological data from this proposal combined with physical and chemical data collected on spring and summerBEST cruises, data from a September NPCREP cruise, and data from moorings and from satellite-tracked drifters to address the hypothesis that the marked difference between the more pelagic southern shelf and the more benthic northern shelf is a result of the position of the sea-ice edge during the transition from strong winter winds to milder summer conditions.

Lead: Jingfeng Wu

We will test the hypothesis that melting ice is a significant source of iron for biological growth in Bering Sea shelf water during spring. Initial spring algal growth depletes available iron in the winter-mixed surface water, resulting in a iron limitation of algal growth. The iron input from melting ice relieves this iron limitation and supports a high level of dissolved iron in the stratified shelf surface water for subsequent algal growth when macronutrients are transported inshore from the iron-poor but macronutrient-rich waters of the Aleutian basin.

We will investigate whether iron in the water immediately beneath sea ice cover is depleted before macronutrients are depleted during the initial algal growth in spring in the absence of available iron input from melting sea ice, and will examine whether melting sea ice is an important source of available iron that leads to a persistent excess of iron in the stratified ice-free shelf surface water.

Lead: Jinlun Zhang

Co-PI: Rebecca Woodgate

We will study historical and contemporary changes of Bering Sea ice cover and the impacts of these changes on Bering Sea climate. We will also investigate future changes of the eastern Bering marine environment under global warming scenarios.

Objectives: (1) simulate the historical evolution of the eastern Bering ice-ocean system since 1970; (2) identify key linkages among the atmosphere, sea ice, and ocean in order to understand mechanisms affecting physical processes influencing the ecosystem; (3) examine the interactions between the Bering Sea climate and the Pacific and Arctic climates; and (4) estimate the state of the marine system under different scenarios of climate change.

Leads: Tom Weingartner, Knut Aagaard

The enormous Bering shelf, containing one of the most productive marine ecosystems in the world, has changed significantly in recent decades, both physically and biologically, and often in concert with regional climate fluctuations. Furthermore, the Bering shelf offers a physical and ecological continuum between the North Pacific and Arctic oceans, and its flow field transmits changes to the northern ecosystems downstream.

We will address the impact of physical variability on the processes and structure of the Bering shelf ecosystem, with special emphasis on how freshwater redistributed by the shelf circulation or introduced from sea ice melt modifies stratification and nutrient distributions. We will ask how changes in sea ice affect advection and mixing; how variable fluxes of low-salinity, nutrient-deficient coastal waters may affect production; how cross-shelf fluxes are established and altered; how these fluxes might respond to climate change; how the seasonal stratification cycle is controlled; and how the buoyant coastal flow evolves.

Leads: Rolf Sonnerup, Terry Whitledge

Co-PI: Calvin Mordy

We will collect, quality control, analyze, and distribute the core physical and chemical observations collected on the BEST summer cruise as a service component of the larger ecosystem program. We will also examine the persistence of along- and across-shelf gradients of temperature, salinity, fluorescence, oxygen, nutrients and currents by integrating data from summer hydrographic surveys with trajectories from satellite-tracked drifters, data from other cruises, and data from long-term moorings (funded elsewhere).