To better understand large-scale ecological changes that could have major economic and cultural implications in the Bering Sea

Photo Credit: Melissa Grego

Explore the Science

Climate scientists predict a major reduction in ice cover over the southern Bering Sea in coming decades, with potential ecological consequences intensifying concern about the future. To better understand and predict the large-scale ecological changes that could have major economic and cultural implications in the Bering Sea and elsewhere, nearly 100 principal investigators from scientific disciplines spanning climate, oceanography, fish and fisheries, seabirds, marine mammals, economics, anthropology, and ethnography joined forces in the Bering Sea Project. Over the course of this complex, seven-year integrated study of the Bering Sea, these principal investigators—together with their many colleagues, technicians, students, ship officers and crews, and other field and laboratory teammates—delved into everything from physics to fish and beyond.

Humans

Photo Credit: Ann Fienup-Riordan

A wide range of communities rely on the Bering Sea for sustenance and cultural life, with some almost wholly connected to the marine waters. Research in local communities was a priority from the outset. Ethnography,anthropology, and subsistence research all had a place in the Bering Sea Project, with more quantitative science operating hand-in-hand with traditional ecological knowledge and the study of natural and cultural history.

Subsistence Harvest Users, and Local & Traditional Knowledge (LTK) Ecosystem Perspective

Leads: Henry Huntington

Co-PIs: Jim Fall, Caroline Brown, Nikki Braem, Ted Krieg, Eugene Hunn, George Noongwook, Taylor Hesselgrave, Astrid Scholz, Pamela Lestenkof, Phil Zavadil

This project examines all animal species harvested by residents of our partner communities. We focus on species that are significant subsistence resources (nutritionally, culturally, or otherwise) and that are also focal species for other Bering Sea Project components. For example, we examine the cultural and subsistence practices regarding walrus in Savoonga, fur seals in St. Paul, and seabirds in all communities, as well as other species or environmental parameters identified through discussion with other Bering Sea Project researchers. Our partner communities are Akutan, St. Paul, Togiak, Emmonak, and Savoonga.

Nelson Island Natural and Cultural Heritage Project

Leads: Mark John

Co-PI: Ann Fienup-Riordan

We will work with elder experts in five Bering Sea communities, non-Native scientists, and younger community members to document their unique natural history and cultural geography, including traditional place names, weather and ice conditions, harvesting patterns, animal and plant communities, and related oral traditions.

Residents recognize that they must document unique aspects of their traditional knowledge in the near future or not at all-- the present generation of elder experts are the last to have received a traditional education in the qasgi (communal men’s house) before the advent of organized religion and formal education.

Community members of all ages are also deeply concerned about the changes in climate and ecology occurring along the Bering Sea coast. Community members feel strongly that elders' perspectives on past periods of resource scarcity, storm surges, and unusual ice and weather conditions, as well as their views on ongoing changes in the Bering Sea ecosystem, will be invaluable in preparing them for the future.

Marine Mammals

Whales and porpoises (or “cetaceans”)found in the Bering Sea cover vast areas in search of the optimal balance between concentrations of their preferred prey and the environmental conditions that best suit their needs. Fluctuations in cetacean abundance and distribution are therefore more likely an indication of broad-scale rather than local changes. Variations in ocean conditions affect the distribution and abundance of important prey species on a large scale. How cetaceans react to these changes in real-time and long-term is still unclear. 

Whale Broad-Scale Distribution

Lead: Nancy Friday

Co-PIs: Phil Clapham, Sue Moore, Alex Zerbini

We will collect sightings of fin and humpback whales during routine annual AFSC/NOAA walleye pollock stock assessment surveys. We will then analyze the sightings to estimate whale density and abundance.

We will also analyze whale distribution data and density estimates in terms of oceanographic and bathymetric variables, prey distribution, and prey density to investigate whale habitat characteristics and to create predictive distribution models. We will include sightings of other cetaceans as sample sizes permit.

Photo Credit: Jodi Frediani

Seabirds

Photo Credit: Michael Johns

The Bering Sea is home to millions of seabirds that breed on islands and coasts, and supports visiting species like shearwaters and albatross. The Pribilof Islands lie near the edge of the Bering Sea shelf and are breeding areas for seabirds including the thick-billed murre (Uria lomvia) and black-legged kittiwake (Rissa tridactyla). Despite their close proximity to one another, seabird populations on St. Paul continued to decline, whereas those on St. George recently stabilized.

Seabird Telemetry

Leads: David Irons, Daniel Roby, Rosana Paredes

We will compare seabird foraging location and trip duration for Black-legged Kittiwakes and Thick-billed Murres nesting on two geographically associated islands in the Pribilof group, St. Paul and St. George.

The maximum edge of the winter ice on the Bering Sea shelf is generally nearer to St. Paul than to St. George. St. George is nearer the productive edge of the Bering Sea shelf. To the extent that the influence of ice is greater in the vicinity of St. Paul, seabirds nesting on that island might be differentially affected by the loss of that influence if future warming reduces the incidence of ice in the area.

This study will allow us to confirm where birds from each island forage, and to look at foraging location and trip duration variability among years of differing sea ice extent. This study will work closely with the seabird colony study to determine the effects of foraging behavior on diets, reproductive success and adult survival.

Seabirds (colony-based)

Lead: Kathy Kuletz

We will examine the relation of seabird distribution to oceanographic and biological features of the eastern Bering Sea. Size, location, and composition of seabird foraging flocks at sea and diet composition can change when prey distribution or abundance changes.

This broad-scale component is closely coordinated with the colony-based seabird projects. At-sea observations will provide data on seabird abundance, distribution, and diet. We will determine seabird responses to changes in oceanographic properties of water masses and to prey type and distribution, and will contrast the patterns of central place foragers (breeding kittiwakes and murres) to that of non-breeding birds (such as shearwaters and albatrosses).

Data collected for this project will also be used to examine seabird and cetacean foraging response to prey persistence, and to retrospectively analyze trophic interactions among fish, birds, and mammals.

Seabird Broad-Scale Distribution

Lead: Heather Renner

These studies focus on response variables for surface-feeding Black-legged Kittiwake and deep diving Thick-billed Murre at breeding colonies on St. Paul and St. George Islands in the Pribilof Islands. We will collect data on seabird reproductive parameters, (clutch size, hatching success, fledgling success, reproductive success, growth rates), timing of nesting events, diets, stress level (part of patch dynamics study B67), annual adult survival, condition of adults (based on body size) and population trends at each island.

We will measure these variables to evaluate inter-annual responses to environmental conditions and prey patch dynamics at breeding colonies on each island. Population indices will be obtained in 2008 and 2011 to provide current data points to assess trends.

Fishes

Fish play a range of starring roles in the year-round drama that is the Bering Sea, from prey for a host of marine creatures during their drifting ichthyoplankton stage to voracious predators in adult form—even cannibalizing their own. And the ecological importance of fish is matched by their importance to subsistence harvests and to the regional economy, with tens of thousands of jobs and several billion dollars annually tied to Bering Sea fisheries.

Acoustic Surveys

Lead: Chris Wilson

We will estimate midwater walleye pollock (age 1+) abundance in the eastern Bering Sea through acoustic-trawl surveys conducted by NOAA Alaska Fisheries Science Center.

Collection of observations of physical oceanography, fish prey fields, and marine mammal and seabirds for related Bering Sea Project work will also take place during these summer cruises.

Surface Trawl Survey Acoustics

Lead: John K. Horne

Co-PIs: Ed Farley, Sandra Parker-Stetter

We will quantify forage fish (e. g. , juvenile pollock, capelin, herring, and myctophids) distribution on the Bering Sea shelf, and examine how oceanography and climate forcing may influence forage fish distribution, abundance, and ultimately effect apex predator distribution and abundance. We will add acoustics and midwater trawling to document density distribution of forage species, and will map forage species distribution and compare distributions and abundances among survey years.

Pollock and Cod Distribution

Lead: Lorenzo Ciannelli

Co-PIs: Kevin Bailey, Steve Barbeaux, Ann Hollowed

We will conduct a retrospective analysis of ichthyoplankton catches of pollock, cod, and arrowtooth flounder and wintertime fisheries data to create species spawning distribution models.

Photo Credit: Steve Barbeaux

Functional Foraging Response

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.

Forage Distribution and Ocean Conditions

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.

Surface Trawl Survey

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.

Bottom Trawl Survey

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.

Food Chain Interactions

Photo Credit: S. Parker-Stetter

The ecological chain connecting nutrients, phytoplankton, zooplankton, fishes, and other predators is quite complex, especially now that microzooplankton are thought to play a role as well. New evidence from the Bering Sea Project has revealed that diatoms are also consumed by protists, single-celled predators known as microzooplankton. How this non-linear food chain impacts larger predators such as commercial fishes, seabirds, and marine mammals and where these predator-prey interactions are occurring are of ecological concern.

Fish, Seabirds and Mammals

Lead: Franz Mueter

Co-PI: Gordon Kruse

We quantify past patterns of variability among of productivity of selected fish, seabird, and marine mammal species over time; test whether historical patterns and trends are consistent with existing hypotheses; suggest new hypotheses based on relationships among the productivity of different ecosystem components and relationships between their productivity and observed climate variability; and provide functional forms and parameter estimates (and their uncertainty) that link the productivity of different ecosystem components to climate variability.

Top Predator Hotspot Persistence

Lead:

Co-PIs: Nancy Friday, Kathy Kuletz, Chris Wilson

The ability to predict the location of prey is an important component of foraging behavior of predators. Predictable prey locations reduce search time and thus energetic costs of foraging. We will analyze data collected from four other projects.

Seabird and cetacean locations from at-sea visual surveys will be analyzed in relation to pelagic forage species abundance and nutritional energy data from acoustic surveys.

We will quantify the existence of prey “hotspots,” whether these hotspots persist across years, and the location of apex predators relative to hotspot persistence based on apex predator frequency of association with persistent hotspots.

Life on the Seabed (Benthos)

The spring bloom creates a short window of time when so much excess food is available that copepods are able to increase their biomass up to 10-fold between early spring and summer. Even so, the zooplankton community does not fully graze the spring bloom, and the ungrazed portion falls to the sea floor, feeding the benthos. The amount of organic matter that falls to the sea floor (also called carbon “export”) varies across the Bering Shelf.

Carbon Export in the Eastern Bering Sea Water Column

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.

Epi-benthic Video Survey

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.

Benthic Ecosystem Response to Changing Ice Cover in the Bering Sea

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.

The Impact of Changes in Sea Ice Extent on Primary Production, Phytoplankton Community Structure, and Export

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.

Nitrogen Supply for New Production and its Relation to Climatic Conditions

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.

Denitrification and Global Change in Bering Sea Shelf Sediments

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.

Sea Ice Algae, a Major Food Source for Herbivorous Plankton and Benthos

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.

Plankton

The intricate connections between ice retreat, intensity of the spring phytoplankton bloom, and the productivity of the Bering Sea motivated researchers to understand the drivers behind the timing and extent of the spring bloom. Ice algae flourish in association with the seasonal ice covering much of the northern portion of the shelf, and in ice-free areas, ocean circulation and biological processes combine to support open-water phytoplankton blooms that feed vast populations of zooplankton.

Ichthyoplankton Surveys

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.

Seasonal Bioenergetics

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.

Summer Microzooplankton in the Bering Sea

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.

Trophic Role of Euphausiids in the Eastern Bering Sea

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.

Mesozooplankton-Microbial Food Web Interactions and Sea Ice

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.

Mesozooplankton Population and Biomass in the Eastern Bering Sea

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.

A Service Proposal to Examine Impacts of Sea Ice on the Distribution of Chlorophyll-a Over 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.

Atmosphere, Ocean, & Climate

The eastern Bering Sea ecosystem is structured in part by seasonal ice, advancing in the late autumn and retreating in the spring. The extent of sea ice is controlled by local and regional weather—wind and cold combine with currents and other oceanographic features to shape the formation, extent, and duration of ice. Oceanographic processes influence life in the eastern Bering Sea, controlling much of the rhythm and change in nutrient availability, plankton populations, etc. These ‘bottom-up’ processes consequently influence fish, birds, and mammals, making them key topics of study in the Bering Sea Project.

Downscaling Global Climate Projections with Nested Biophysical Models

Leads: Nicholas Bond, Enrique Curchitser, Katherine Hedstrom

Co-PIs: Georgina Gibson, Albert Herrmann, Jim Overland

We will test these hypotheses:

  • Climate-induced changes will alter food availability for all trophic levels of the shelf ecosystem through “bottom-up” processes (processes beginning at the bottom of the food web and moving up through trophic levels).
  • Earlier sea ice retreat expected as a result of warming will result in a later, warm-water spring phytoplankton bloom, increased coupling with zooplankton and greater pelagic secondary productivity. Benthic secondary productivity will decrease.
  • Reduction in frequency and intensity of summer storms will reduce surface mixing and increase surface insolation. This will increase stratification and lower the supply of nutrients that sustain primary and secondary productivity. The resultant summer and fall conditions will reduce zooplankton and juvenile fish production by reducing their condition (energy density) and over-wintering capability.

Photo Credit: E.  Cokelet 

Role of Ice Melting in Providing Available Iron to the Surface Water of the Eastern Bering Sea Shelf

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.

Impact of Changes in Sea Ice on the Physical Forcings of the Eastern Bering Ecosystem

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.

Stratification on the Bering Shelf and its Consequences for Nutrients and the Ecosystem

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.

Examining Summer Hydrographic Structure and Nutrients

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).

Ecosystem Modeling

To weave together existing and new information at the ecosystem level, the Bering Sea Project invested in an ambitious numerical modeling effort anchored in physical oceanography. The models explored both “bottomup” (resource-limiting) mechanisms, such as climate and physics, as well as “top-down” (predation) forces, such as fisheries and management strategies.

Fish, Seabirds and Mammals

Lead: Franz Mueter

Co-PI: Gordon Kruse

We quantify past patterns of variability among of productivity of selected fish, seabird, and marine mammal species over time; test whether historical patterns and trends are consistent with existing hypotheses; suggest new hypotheses based on relationships among the productivity of different ecosystem components and relationships between their productivity and observed climate variability; and provide functional forms and parameter estimates (and their uncertainty) that link the productivity of different ecosystem components to climate variability.

Top Predator Hotspot Persistence

Lead: Mike Sigler

Co-PIs: Nancy Friday, Kathy Kuletz, Chris Wilson

The ability to predict the location of prey is an important component of foraging behavior of predators. Predictable prey locations reduce search time and thus energetic costs of foraging. We will analyze data collected from four other projects.

Seabird and cetacean locations from at-sea visual surveys will be analyzed in relation to pelagic forage species abundance and nutritional energy data from acoustic surveys.

We will quantify the existence of prey “hotspots,” whether these hotspots persist across years, and the location of apex predators relative to hotspot persistence based on apex predator frequency of association with persistent hotspots.

Predator-Prey Dynamics

We define “patches” as significant spatial variation in any feature of prey that is important for exploitation by predators. Prey patches may occur at scales of <1 meter to several kilometers, and may last anywhere from minutes to months. Patches also vary in species composition, biomass, energy content of prey, and distribution (size of patch, density within a patch, density of patches, and distance from colony/rookery).

We don't know how top predators respond to variability in prey patches (patch dynamics) and the consequence this has on population dynamics of top predators in the Bering Sea. We need this fundamental information to predict how the Bering Sea ecosystem will respond to global warming.

Patch Dynamics

Lead: Andrew Trites

Co-PIs: Kelly Benoit-Bird, Heather Renner, Vernon Byrd, Jackie Grebmeier, Scott Heppell, David Irons, Chad Jay, Sasha Kitaysky, Kathy Kuletz, Dan Roby

We are studying birds, mammals, and their forage bases to determine the consequences of spatial patterns (patches) on predator-prey dynamics.

We will seek to determine how groups of species are controlled -- by fishing, predators, food availability, the physical environment, or a combination of all four.

Photo Credit: Andrew Trites