Chukchi Ecosystem Observatory

Deployment of CEO sensor array in 2017. Photo courtesy of UAF.

Location of Data

Data are posted to the CEO project website (click button below), and uploaded to the Axiom Research Workspace for NPRB Project #1426. Data will also be made available with some visualization capability through the AOOS Data Portal in the coming years. An attempt is made to post the raw data online immediately following the recovery cruise and processed data within six months, when possible; however, PIs can extract and provide data directly to interested users on request.

The Need

Moored oceanographic observations are essential for understanding time-varying ocean processes under different environmental conditions. Wave, current, and other physical measurements allow assessment of co-variability in the light, chlorophyll, CDOM, nitrate, backscatter, particle size distribution, zooplankton and fish parameters. The objective of Chukchi Sea Ecosystem Observatory (Mooring) (referred to as the CEO) project is to maintain a multi-parameter, multi-instrument physical/biological/chemical/geological oceanographic mooring in the Northeast Chukchi Sea. The CEO is designed to aid management of subsistence resources and potential commercial fisheries by providing data valuable to an ecosystem-based approach to resource management. The CEO site is also well situated to monitor the state of ocean acidification, changes to shelf nutrient and carbon cycles, and how changing wind, wave, and ice affect the regional oceanography. The observatory provides biogeochemical model validation data, improving our understanding of the marine carbon pump and shelf-basin exchanges. The project complements water column, benthic, and passive acoustics sampling carried out by other programs, and places ship-based sampling programs into a significantly more complete temporal context, including measurements of the National Science Foundation (NSF)-supported Distributed Biological Observatory (DBO) project, serving as a year-round “anchor” for the DBO monitoring region #4. It also complements previous industry-funded Chukchi Sea Environmental Studies Program (CSESP), the ongoing Arctic Marine Biodiversity Observation Network (AMBON), and the NPRB Arctic Integrated Ecosystem Research Program (Arctic IERP).  

CEO datasets will have many applications, including:

  • Providing independent validation points for biogeochemical and ecosystem models. 
  • Enabling estimates of the particulate fluxes to the seafloor that directly supply the benthic community with organic matter and, in turn, support the key summer walrus foraging area in the vicinity. 
  • Delivering active acoustic data indicating the presence of Arctic Cod (a subsistence resource and marine mammal prey) and euphausiids (Arctic Cod and bowhead whale prey). 
  • Providing passive acoustic recordings to document the presence of anthropogenic noises and vocal marine mammals, including walrus, bearded seals, and whales. 

Project Location

Caption here.

AOOS’s plan to establish sentinel ecosystem moorings in each of the Large Marine Ecosystems (LMEs) in Alaska designates moorings in the Gulf of Alaska, the Bering Sea, the Chukchi Sea and the Eastern Beaufort Sea. The general location for each observatory is selected based on the biological, economic, and cultural importance associated with each region and is founded on how each site is positioned to document the effects of shelf-canyon exchanges that regulate biological production, biodiversity, and community structure. The Chukchi Sea LME is illustrated in the diagram below.  Establishing this modern-era observing consortium is at the forefront of expanding the Alaska-region marine observing capacity, providing the research and resource and fisheries management communities with unparalleled, long term datasets for discovery and improvements in ecosystem modeling. 

The CEO was initially established with primary support from AOOS and the North Pacific Research Board’s (NRPB) Long-term Monitoring program. It started with a single mooring deployed in 2014 on the southern flank of Hanna Shoal in 45 m of water. This mooring site was selected, because it is considered a “ biological “hotspot” located on the northeast Chukchi Sea shelf, where a thriving benthic community supports walrus foraging activity during summer months. Since 2014, moored instruments have been deployed, annually recovered and re-deployed. The array now includes up to three co-located moorings. The sensors do not report real time data, except when the Ice Detection Buoy (IDB) is deployed. The IDB reports real time information up through freeze-up, afterwhich the surface float is released, and the remaining sensors below record throughout the winter months. Due to ice conditions for at least six months of the year, the majority of CEO instruments record data internally year-round, and these data are recovered during the annual mooring turn-around. 

Project Details

The mooring configuration shown below illustrates a recent configuration of three moorings that make up the CEO array. This configuration enables many stand-alone studies as well as the core CEO parameters of interest. 

Abbreviations include: ADCP = Acoustic Doppler Current Profiler; SBE37 and SBE16 = Sea-Bird Electronics temperature/salinity dataloggers; AURAL = passive acoustics sound recorder; RCM = recording current meter; AZFP = Acoustic Zooplankton and Fish Profiler; SBE43 = Sea-Bird Electronics dissolved oxygen sensor; WETLabs ECO-Triplett = Chlorophyll a, optical backscatter and colored dissolved organic matter (CDOM) sensor; SUNA = Satlantic nitrate sensor datalogger. Eric note: This image is fairly low res – would be best to replace with higher res version if possible.

The following table provides details about the mooring configuration and lists the specific instrumentation being deployed, annually in most cases.

Manufacturer & InstrumentMeasured & Derived ParametersSample Depth (Resolution)Temporal Resolution
TRDI Workhorse Waves ADCPCurrent velocity & 600 KHz signal strength    3-30 m (1 m bins)1 hr
TRDI Workhorse Waves ADCPSignificant Wave Height, Period & DirectionSurface3 hr
TRDI Workhorse Waves ADCPTemperature & Pressure31 m1 hr
ASL Acoustic Zooplankton Fish Profiler38, 125, 200 & 460 KHz Acoustic Backscatter 0.5-30 m (4 cm bins)15 s
Sea-Bird ScientificSBE-16 SeaCat & ancillary sensorsTemperature, Conductivity, Salinity, Pressure, Dissolved Oxygen, Colored Dissolved Organic Matter, Optical Backscatter, Photosynthetically Available Radiation (PAR), Chlorophyll a fluorescence34 m1 hr
Satlantic SUNA V2Nitrate34 m1 hr
Contros HydroCPartial Pressure of CO234 m1 hr
SeaBird SeapHOxpH, Dissolved Oxygen, Temperature, Salinity34 m1 hr
Sequoia LISSTParticle size spectra & concentrations34 m1 hr
Sea-Bird SBE-37 MicroCat Temperature, Conductivity, Salinity & Pressure44 m (in some years, every 10m from surface to seafloor)15 min
Multi-Electronique AURALMarine Mammal Vocalizations & Vessel NoiseFull ocean depth on the Chukchi Shelf (1-45 m)1 hr
GreenEyes AquaMonitorNitrate, Nitrite, Phosphate, Silicate, d18O, Phytoplankton species38 m2 weeks (47 samples)
HydroBios Multi Sediment TrapChlorophyll a, Phytoplankton species, Total particulate matter (dry wt.), Particulate organic carbon & nitrogen, Zooplankton species, stage & fecal pellets38 m5 days to 4 weeks (24 samples)

Expanding the suite of existing water column ecosystem moorings in the coastal regions of the United States is one of the recommendations of the National Strategy for a Sustained Network of Coastal Moorings.  Alaska’s CEO is serving as a model to the ocean observing community around the world on how to establish and implement a successful and effective ecosystem mooring observatory consortium (National Ecosystem Mooring Workshop Report).

The CEO has been successfully deployed and recovered annually since its inception. Though still early in implementation, the data are already contributing to a much deeper understanding of the oceanography, fauna and flora of the northeast Chukchi shelf.  As the CEO time series record increases, it will become even more valuable to scientific research. 

Project Highlights

Together, the research highlights listed below reflect some of the increasing level of sophistication in understanding the physical and biogeochemical dynamics that support the Hanna Shoal ecosystem. 

  • Weak currents with variable vectors contribute to the depositional nature of the CEO site, where pelagic export to the benthos supports the locally high benthic biomass. 
  • Acoustic scattering signals that most likely represent Arctic Cod and large crustacean zooplankton show significant vertical motions throughout the year, including under the ice during the polar night.
  • In contrast to expectations, alternating episodes of water column stratification and re-homogenization occurred throughout the year, even in the middle of winter.
  • Mid-depth instruments have continuously recorded temperatures rising and salinities falling just before the summer transition to open water, observations not possible without year-round subsurface mooring capability.
  • Elevated levels of photosynthetically available radiation, sufficient to support photosynthesis, have been detected below relatively thick ice in May and June.
  • Enhanced total particulate matter and particulate organic carbon (POC) fluxes during the open water period reflects the influence of fall storms that caused resuspension on the shallow shelf.
  • High abundances of early stage polychaetes and bivalves have been observed in the water column during fall.
  • High POC, chl a and diatom fluxes reflect high primary productivity in the absence of ice (August-October) and during ice melt (June-July).
  • High fluxes of Nitzschia frigida reflect release of ice algae from sea ice melt in May and June.
  • Elevated fluxes of the benthic-planktonic diatom Cylindrotheca closterium during fall suggest rapid growth during and following mixing events in shallow waters.

Funding Sources

The leveraged distribution of support for the CEO spreads the burden of equipment purchases, operations, maintenance, and data cleanup among the various consortium partners including UAF, AOOS, and NPRB. 

  • UAF and AOOS supply the equipment needed to outfit the observatory. 
  • NPRB and AOOS support covers ongoing operational expenses. 
  • All partners provide outreach. 
  • NPRB, AOOS and UAF jointly support data processing and archiving, and making data publicly available.

During the initial years of the CEO, industry-based activities were able to provide much of the annual vessel servicing support and were expected to be able to do so for several years out. However, following the 2015 departure of Shell from the Chukchi Sea, alternatives needed to be identified. The PIs have been able to take advantage of “ships-of-opportunity” deployments thus far. Together, these consortium contributions constitute a CEO effort of $1.6M over 2014-2019, not counting the additional partner contributions. In Spring 2018, the NPRB Board committed to re-funding the CEO project for another 5-year cycle, which allows the CEO to sustain observing capacity.


The CEO provides a significant basis for Chukchi shelf research and has provided a foundation for additional contributions beyond those described in the original NPRB Project #1426 LTM proposal. The most high-profile of these leveraged efforts includes the following data collections, analyses and ship-based samplings that complement the originally funded efforts:

  • Passive acoustic recordings and analyses of Dr. K. Stafford (U. Washington); 
  • Sediment trap deployments and analyses of Dr. C. Lalande (U. Laval); 
  • Analysis of the active acoustic data by Dr. J. Horne and Ms. S. Gonzalez (U. Washington); 
  • A new discrete water sampler by Dr. S. Danielson (UAF) and water sampler discrete chemical analyses by Dr. L. Cooper (UMCES) and Dr. C. Mordy (NOAA-PMEL).
  • An experimental IOOS-funded real-time mooring designed to help the NWS predict freeze-up on the Chukchi shelf by Dr. P. Winsor (UAF) (the Ice Detection Buoy);
  • AMBON, DBO, NCIS and other projects that have taken chemical, biological and physical samples near the CEO site. A plan in place will re-locate the DBO-4 transect so that it passes immediately by the CEO, ensuring future vessel visits to the mooring site. 



  • Danielson, S. L., L. W. Cooper, J. M. Grebmeier, C. Hauri, K. Iken, R. R. Hopcroft, J. H. Horne, C. Lalande, A. M. P. McDonnell, K. M. Stafford, P. Winsor (2017), Collaborative approaches to multi-disciplinary monitoring of the Chukchi shelf marine ecosystem, MTS/IEEE Oceans17 conference proceedings, Anchorage, AK, pp. 1-7
  • Hauri, C., Danielson, S., McDonnell, A.M.P., Hopcroft, R.R., Winsor, P., Shipton, P., Lalande, C., Stafford, K.M., Horne, J.K., Cooper, L.W., Grebmeier, J.M., Mahoney, A., Maisch, K., McCammon, M., Statscewich, H., Sybrandy, A., and Weingartner, T., 2018. From sea ice to seals: A moored marine ecosystem observatory in the Arctic, Ocean Science, 14, 1423-1433, 
  • Lalande, C., J. Grebmeier, S. Danielson, in review. Annual cycle of biogenic matter export on the Chukchi Sea continental shelf: 2015-2016. To be submitted to Geophysical Research Letters.
  • Gonzalez, S., et al., Temporal variation of fish and zooplankton densities in a marine Arctic ecosystem, ICES Working Group on Fisheries Acoustics, Science and Technology, April 2019, Galway, Ireland
  • Gonzalez, S., et al., Temporal variation in densities and vertical distributions of pelagic fish and microzooplankton on Hanna Shoal, Alaska Marine Science Symposium, January 2019, Anchorage, Alaska
  • Hauri, C., et al., From sea ice to seals: A moored marine ecosystem observatory in the Arctic, Arctic Observing System, June 2018, Davos, Switzerland (posterpresentation).
  • Hauri, C., et al.,  Seasonal and interannual inorganic carbon dynamics in the Chukchi Sea, American Geophysical Union Fall Meeting, December 2018, San Francisco (poster presentation).
  • Hauri, C., et al.,  Seasonal and interannual inorganic carbon dynamics in the Chukchi Sea, Alaska Marine Science Symposium, January 2018, Anchorage (posterpresentation).
  • Danielson, S., Ice floes to seals, waves to whales. Linking high latitude marine ecosystem studies and researchers through physics. Invited oral presentation. Sitka Whale Fest 2017, Sitka, AK, Nov. 2017
  • Danielson, S. et al., Chukchi Ecosystem Observatory. Oral presentation. Distributed Biological Observatory and Pacific Arctic Group meetings, Seattle, WA. Nov. 2017
  • Danielson, S. et al., U.S.-Canada Northern Oil and Gas Research Forum, Oral presentation. Anchorage, AK, Oct. 2017
  • Danielson, S. et al., Collaborative approaches to multi-disciplinary monitoring of the Chukchi shelf marine ecosystem: Networks of networks for maintaining long-term Arctic observations. Oral Presentation. MTS/IEEE Oceans17 meeting, Anchorage, AK, Sept. 2017
  • Danielson, S., Attempting Multi-Disciplinary Measurements at Biologically & Physically Relevant Time & Length Scales, Invited oral presentation. Polar Marine Science Gordon Research Conference, Ventura, CA, Mar. 2017
  • Danielson, S. et al., Hanna Shoal Year-Round: Emerging Results from the CEO. Poster presentation. Alaska Marine Science Symposium, Jan. 2017
  • Danielson, S. et al., Chukchi Ecosystem Observatory: presentation to the Distributed Biological Observatory and Pacific Arctic Group meetings, Nov. 2016, oral presentation
  • Danielson, S. et al., Chukchi Ecosystem Observatory, Oral presentation. Alaska Ocean Observing System Board Meeting, Fairbanks, AK, Mar. 2016
  • Danielson, S. et al., Chukchi Ecosystem Observatory, Oral presentation, Interagency Arctic Research Policy Committee (IARPC), Feb. 2016
  • Danielson, S. et al., A Northeastern Chukchi Shelf Ecosystem Observatory: Year 1 Results and Year 2 Build-out. Oral presentation. Alaska Marine Science Symposium, Jan. 2016
  • Danielson, S. et al., Chukchi Ecosystem Observatory. Oral presentation. Distributed Biological Observatory and Pacific Arctic Group meetings, Seattle, WA. Nov. 2015
  • Danielson, S. et al., A Northeastern Chukchi Shelf Ecosystem Observatory. Oral presentation by video conference. National Academy of Sciences Polar Research Board, Nov. 2014
  • Hauri, C. et al., Monitoring Ocean Acidification with the Chukchi Shelf Ecosystem Observatory. Poster presentation. Global Ocean Acidification Network workshop; Oceans in a High CO2 World conference, Melbourne, Australia, May 2016
  • Janzen, C. et al., What is going on up there? – The Chukchi Sea Ecosystem Mooring. Poster presentation. AGU/ALSO Ocean Sciences Meeting 2016, New Orleans, LA, Feb. 2016
  • Lalande, C. et al., S. Pelagic-benthic coupling in the Chukchi Sea: Annual cycle of biogenic matter fluxes on the most productive Arctic shelf. Oral presentation. Arctic Change Conference. Québec, Canada, Dec. 2017
  • Lalande, C. Monitoring the impact of sea ice on the pelagic marine ecosystem using export fluxes. Invited oral presentation. Alfred-Wegener Institute Helmholtz Centre for Polar and Marine Research. Bremerhaven, Germany, Dec. 2017 
  • Lalande, C., et al., Annual cycle of biogenic matter exported on the Chukchi Sea continental shelf: 2015-2016. Poster presentation. Gordon Research Conference. Ventura, California, USA, Mar. 2017

Principal Investigators

Seth Dainelson profile photo.
Seth Danielson
University of Alaska, Fairbanks, CFOS
Claudine Hauri
University of Alaska, Fairbanks, IARC
Russ Hopcroft
University of Alaska, Fairbanks, CFOS
John Horne
University of Washington

Catherine LaLande
Département de biologie, Université Laval, Québec City, Canada
Profile photo for Andrew McDonnell
Andrew McDonnell
University of Alaska, Fairbanks, CFOS
Kate Stafford
University of Washington
Applied Physics Laboratory
Peter Winsor profile photo.
Peter Winsor
World Wildlife Fund

Tom Weingartner
University of Alaska, Fairbanks, CFOS