Given its scope, the CASES initiative summons a large fraction of the Canadian and foreign expertise in Arctic oceanography.  In Canada, the network includes Principal Investigators (PIs) from 10 P. Wassman, M. Fortier, D. Smith, D.Barber, L. Fortier, J. Deming, G. Stern, E. DewaillyCanadian universities, 4 Federal Departments (Fisheries & Oceans, Environment, Natural Resources, Defense) and the Canadian Museum of Nature. The Canadian Coast Guard and the Polar Continental Shelf Project provide the essential administrative, logistic and navigational expertise for an Arctic endeavour of this extent. The CASES Network has merged this complementary regional expertise into a network comprising 42 Canadian Arctic researchers and over 30 Arctic specialists from 9 foreign countries (USA, Japan, UK, Denmark, Russia, Poland, Norway, Belgium, Spain).

The Network and the strong and broad scientific motivations for CASES, we expect an ultimate convergence of the diverse, often discipline-specific, views onto a powerful interdisciplinary understanding of the issues that would not otherwise be possible. The science program detailed in the remainder of the proposal comprises 9 subprojects.

1. Atmospheric and Sea Ice Forcing of Coastal Circulation
2. Ice-Atmosphere Interactions and Biological Linkages
3. Light, Nutrients, Primary and Export Production in Ice-Free Waters
4. Microbial Communities and Heterotrophy
5. Pelagic Food Web: Structure, Function and Contaminants
6. Organic and Inorganic Fluxes
7. Benthic Processes and Carbon Cycling
8. Millenial-Decadal Variability in Sea Ice and Carbon Fluxes
9. Coupled bio-physical models of the carbon flows on the
    Canadian Arctic Shelf

Canadian Principal Investigators: Ingram (Co-leader), Carmack (Co-leader)
Grant Ingram 
G. Ingram     E. Carmack
Gratton, Marsden, Melling
Canadian Collaborators: Barber, Galbraith, PR Hill, Kelley, Miller, Solomon
Foreign Collaborators: Appel (USA), Davis (UK), Hughes (UK), Guest (UK), Johnson (USA), Maslanik (USA), Maslowski (USA), Minnett (USA), Muenchow (USA), Wadhams (UK), Weatherly (USA)

SYNOPSIS: The physical oceanographic component of the CASES network will examine the physical processes responsible for the observed water mass and circulation characteristics on the Mackenzie Shelf from an area east of the Mackenzie River mouth to the Amundsen Gulf. We propose an intensive integrated study of the Mackenzie shelf to help understand the causes and ecological consequences of climate variability in the western Canadian Arctic. The field work will include CTD and standard vertical profile measurements during different seasons, as well as current meter moorings. Sediment traps will also be deployed from the moorings. Linking the sea ice and meteorological conditions, as well as hydrographic and circulation, to the generation and maintenance of the Cape Bathurst polynya will be one of our major objectives. Relating the physical conditions to the biological populations and vertical fluxes of carbon on the Shelf and in the polynya is another major focus of our project.

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Canadian Principal Investigators: Barber (Project Leader),

D. Barber

DeAbreu, Flett, Papakyriakou, Ramsay, Yackel
Canadian collaborators:
Fortier, Gosselin, Michel, Poulin
Foreign Collaborators: Hattori (JPN), Melnikov (RUS), Nghiem (USA), Rysgaard (DEN), Shirasawa (JPN), Tynan (USA), Ushio (JPN), Weslawski (POL)

SYNOPSIS: The snow cover on sea ice is an important physical variable which impacts energy, physical and chemical processes operating across the ocean-sea ice-atmosphere (OSA) interface. Physically, the snow cover contributes to determining the magnitude and rate of ice growth and decay. Biologically, the snow-covered sea ice cycle strongly constrains annual primary production in polar seas. The primary objective of our subproject is to assess the impact of variability in climatic and physical forcing of the snow and ice cover on the ice-related biological component of the Arctic ecosystem. Extensive measurements are going to be made in order to 1) determine the relative contributions of atmosphere, oceanic and hydrologic forcing on sea ice accretion and ablation processes, 2) examine the nature of snow deposition, aeolian transport, and metamorphism throughout the annual cycle, 3) determine the relationship between variability of the radiative transfer of shortwave radiation as a function of variability in snow and sea ice processes, 4) estimate radiative transfer in the snow/sea ice system using microwave remote sensing and a snow/sea ice thermodynamic model, 5). determine the relationship between the evolution of the (optical) radiative transfer in the snow/sea ice system and the dynamics of the epontic and under-ice phytoplankton production, and 6) determine the export pathways (export to depth vs trophic) of primary production under landfast ice. Our penultimate goal is to arrive at a coupled atmosphere-snow-ice-ocean model of carbon flow under landfast ice. While most other subprojects will be focussing on the important lead polynya and drifting pack ice regions of the study area, this subproject will be the primary test site for investigation of the processes which couple epontic and under-ice primary production, and associated ecological conditions, to the processes of landfast sea ice accretion and ablation. We see this work as fundamental to understanding the relationship between sea ice variability and the biological response to this variability in the landfast ice portion of the study area, which is representative of a significant area of the Arctic shelves (Canadian Archipelago, Siberian Shelves).

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Canadian Principal Investigators: Demers (Leader)
S. Demers

Gosselin, Larouche, Michel, Poulin, Price.
Canadian Collaborators: Deibel, Fortier, PRHill, Miller, Vincent
Foreign Collaborators: Booth (USA), Fukuchi (JPN), Horner (USA), Kirillova (RUS), Kudoh (JPN), Murray (USA), Odate (JPN), Saitoh (JPN), Taguchi (JPN), Urban-Rich (USA), Vernet (USA), Walsh (USA), Yager (USA)

SYNOPSIS: According to the central hypothesis, atmospheric, oceanic and hydrologic forcing of sea ice extent will dictate the overall seasonal production of phytoplankton in ice-free waters on the Mackenzie Shelf. Once the ice cover removed, the timing of water column stabilisation will determine the onset of the phytoplankton bloom, the duration of the biological production season and the final stage reached by the phytoplankton succession. In early spring, the availability of photosynthetically active radiation (PAR) in the surface layer of the open waters is determined by a combination of physical processes including wind induced turbulent mixing, convection due to ice formation, haline stratification due to ice melt, solar warming of the surface layer and turbidity. Later in the season, nutrient availability may limit production and affect the phytoplankton assemblage. In collaboration with several other sub-projects, our team will study seasonal and interannual variability in the relative importance (versus ice algae, subproject 2.2), nature (new versus regenerated) and exportation (recycling, grazing, sinking, sub-projects 2.4, 2.5, 2,6) of phytoplankton production in response to these processes (sub-project 2.1), in the flaw lead and the Cape Bathurst polynya. Light spectral intensity, nutrient availability, size-fractionated phytoplankton biomass, and production, phytoplankton distribution (direct mapping and satellite images), taxonomy, and nutrient uptakes will be measured in the ice-free waters of the three oceanographic provinces of the study area. Satellite monitoring of ocean colour and the comparison of production and taxonomy in August of the three years (2002, 2003 and 2004) will enable us to assess interannual variability in response to the seasonal pattern of polynya formation (e.g. Fig. 3). The same continuous measurements, from August 2002 to August 2003, will allow us to monitor phytoplankton dynamics over the strong annual cycle in physical and chemical forcing on Arctic shelves.

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Canadian Principal Investigators: Vincent (Project Leader),
W. Vincent

Canadian Collaborators: Demers, Miller
Foreign Collaborators: Deming (USA), Dickson (USA), Rysgaard (DEN), Lancelot (BEL), Pedrós-Alió (SPA), Sherr B. (USA), Sherr E. (USA), Wilmotte (BEL), Yager (USA).

SYNOPSIS: In previous sections, it was hypothesised that climate change exerts a control on the timing and duration of open water conditions in the offshore polynya that in turn influences the extent of processing of organic material in the delta versus polynya regions. In this subprogram we will examine the microbial communities and processes which characterise the two types of environment, and the implications for community structure and organic matter processing under the two polynya scenarios (P1 and P2 above). We will measure rates of microbial heterotrophy to assess the phototrophic-heterotrophic balance across the study region and will examine the size distribution and particle association of microheterotrophs (including protists) that influence the fate of microbial production. We will determine the temporal variations in microbial community structure (viruses, bacteria, picocyanobacteria and protists) that are likely to affect organic matter fluxes; these measurements will be conducted at weekly intervals at the polynya and delta sites, with two synoptic transects that will include sampling across the freshwater-saltwater transition of the Mackenzie River. We will experimentally evaluate the influence of light (open water versus ice cover) on microbial community structure and processes; and the relative importance of viral lysis versus microzooplankton grazing on the picoplankton as two mechanisms of organic matter processing that regulate the offshore export of particulate carbon.

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Canadian Principal Investigators: Deibel (Leader)
D. Deibel

Fortier, Gagné, Reist, Runge, Stern
Canadian Collaborators: Barber, Demers, Gosselin, Larouche, Macdonald, Vincent
Foreign Collaborators: Ashjian (USA), Campbell, Daly (USA), Dickson, Hattori (JPN), Kwasniewski (POL), Moore (USA), Nielsen (DEN), Straley (USA), Takahashi (JPN), Tanimura (JPN), Tynan (USA),
Wassman (NOR), Weslawski (POL)

SYNOPSIS: In previous sections, hypotheses were developed concerning the mechanisms by which climate-driven variability in the extent, duration and snow load of sea ice regulate fluxes of dissolved and particulate organic and inorganic carbon on the Mackenzie Shelf. In addition to remineralization by microbial heterotrophs (subproject 2.3 and 2.6), various processes mediated by metazoan zooplankton may modify the magnitude, nature and direction of carbon flux. These processes include remineralization of organic carbon into CO2 by respiration; repackaging of small particles into larger, rapidly-sinking faecal pellets by feeding; the destruction of sinking faecal pellets by coprophagy; the conversion of particulate carbon into DOC by sloppy feeding and excretion; the vertical transport of carbon by vertical migration; and the trophic flux of organic carbon and contaminants from primary producers to large vertebrate predators. The four main zooplankton groups mediating these processes are copepods, appendicularians, macrozooplankton predators, and fish larvae. By affecting primary production and zooplankton abundance, sea ice dynamics ultimately govern interannual variability in the impact of these processes on carbon flux. Our objective is to quantify these processes over an annual cycle, under the landfast ice, in the flaw polynya and at the edge of the Arctic ice pack. In these three areas we will (1) determine the abundance, vertical distribution and vertical migration of the zooplankton community, including juvenile and adult fish, (2) determine respiration, grazing, faecal pellet and egg production rates of copepods and appendicularians, (3) determine the feeding rates of macrozooplankton predators, and (4) determine the feeding, growth and survival rates of the early life history stages of fish. In addition, we will (5) determine seasonal variability in the trophic structure of the pelagic food web using stable isotopes, and (6) quantify the trophic flux of contaminants in the ecosystem. These data will enable us to test the hypothesis that an early and wide opening of the flaw polynya shifts the ecosystem of the continental shelf towards a herbivorous food web in which the net export of carbon both to depth and to pelagic animals is favoured relative to microbial remineralization (P1 and P2 of the central hypothesis).

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Canadian Principal Investigators: PR Hill (Co-leader), Macdonald (Co-leader)
P.R. Hill        R. Macdonald

Grant, PS Hill, Mucci, Sundby
Canadian Collaborators: Miller, Michel, Solomon, Mudie, Rochon, Galbraith, Ingram, Melling, Carmack, Milligan.
Foreign Collaborators: Cochran (USA), Daly (USA), Deming (USA), Moran (USA), Murray (USA), Rysgaard (Denmark), Walsh (USA), Wassman (NOR), Yager (USA)

SYNOPSIS: The central hypothesis for the CASES project relates to the carbon fluxes in the Mackenzie Shelf - Beaufort Sea areas. These fluxes can take place in dissolved or particulate phases, in both vertical and horizontal directions and involve complex interactions between the phases. Important fluxes include burial in sediments, exchange with the interior ocean and supply of material from the land. The large source of inorganic sediment, organic carbon, nutrients and alkalinity from the Mackenzie River interacts with marine DOC and POC through flocculation and adsorption. High turbidity of the Mackenzie plume suppresses primary production whereas stability from the freshwater input encourages it. Finally, the large inorganic load from the Mackenzie supports a potentially large burial flux. The general objectives of this subproject are to quantify these different fluxes over the annual cycle and to understand the principal interactions between the atmosphere, organic and inorganic carbon in the water column and detrital sediment particles. We hypothesize that dense shelf waters generated by ice formation in winter transport globally important quantities of remineralized carbon into the interior Arctic Ocean within or below the halocline. The large freshwater lens of the Mackenzie plume is an important control on this transport, particularly as it forces estuarine transport across the shelf, supports chemical flocculation and burial, and leads to density stratification which supports marine primary production. In the nearshore, we suggest that the sediment load of the Mackenzie will have a large negative effect on primary production and carbon fixation and that these may therefore be displaced to the central or outer shelf. Organization of the primary production spatially and between ice and pelagic production has important consequences for the flow of carbon through food webs and the coupling of primary production with benthic production. In addition to the supply of terrestrial organic carbon, the horizontal flux of suspended sediment and the timing of high turbidity levels relative to peak production are critical to the total carbon budget. Whereas decreased ice cover favours greater pelagic production, higher turbidity from a spreading plume may lead to reduced production. Finally, the interactions between organic and inorganic particles profoundly influence the settling and sequestration of organic carbon into bottom sediments on the shelf. Scour by ice on the inner shelf together with fall storms that resuspend coastal sediment profoundly affect the metabolism and preservation of organic carbon in these sediments. These processes which include microbial metabolism, autotrophic and heterotrophic production, ingestion and transformation by zooplankton as well as hydrolysis and transformation by the extracellular enzymes of bacteria are critical to he understanding of vertical fluxes.

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Canadian Principal Investigators: Aitken (Project Leader)
A. Aitken

Conlan, Gagnon
Canadian Collaborators: Deibel, PR Hill, Macdonald, Poulin
Foreign Collaborators: Ambrose (USA), Clough (USA), Renaud (USA)

SYNOPSIS: This component of the research program will examine the processes that influence benthic community structure and respiration on the Mackenzie Shelf. Benthic organisms are anticipated to respond to seasonal variations in the rate of sedimentation of clastic sediments and organic detritus, as well as annual variations in the magnitude and frequency of ice scour. Changes in the structure of benthic communities will influence the rate of oxygen consumption (a proxy for carbon remineralization) at the seafloor. Carbon fluxes to the seafloor will be monitored by sediment traps deployed to capture settling inorganic and organic materials. The relative food quality of these materials will be assessed by the analysis of total organic matter and pigment contents. A combination of sidescan sonar, box coring and bottom photography will provide materials for the analysis of the physical properties of the seafloor and benthic community structure. Of particular interest is the determination of the abundance and species composition of benthic macrofauna and megafauna, and the rate of benthic recolonization of ice scours. Oxygen consumption will be assessed through incubations involving infaunal organisms and epifaunal organisms, separately. The shells of benthic invertebrates (notably molluscs and echinoderms) recovered from the Mackenzie Shelf will provide suitable materials to examine the utility of biogeochemical "markers" as proxies for the sources of organic materials consumed by marine benthos.

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Canadian Principal Investigators: Mudie (Co-leader), Scott (Co-leader)
P. Mudie          D. Scott

Blasco, Cranston
Canadian Collaborators: Solomon, PRHill
Foreign Collaborators: Bischof, Darby (USA); Campeau (Belgium); JAMSTEC (Japan)

SYNOPSIS: The central objective of this CASES project arises from the premise that historical changes in Arctic sea ice and related ecosystem responses may reflect global warming and anthropogenic greenhouse effects. Proxy-data from marine sediments in the eastern Arctic and Chukchi seas, however, show that greater changes occurred in the past, including ice-free intervals and relocations of the Beaufort Gyre. Validation of regional models of ecosystem responses to Arctic ocean-atmosphere forcing thus requires geological proxy-data to define realistic initial values for "warmer-than-now" scenarios. The main objectives of this paleoclimate sub-proposal are to obtain decadal-millenial scale records of quantitative variations in Mackenzie River discharge, sea ice conditions, summer sea surface temperature (SST), salinity, primary productivity and carbon storage during the past 10,000 years. Changes in the Beaufort Gyre and shelf water circulation will also be determined from the provenance of ice rafted detritus, which documents the history of the Arctic Oscillation. We hypothesise that proxy-data from two cross-shelf transects of sediment cores will record SST oscillations of about 2-4oC, with concomitant reductions in sea ice extent and increased bioproduction. The extent of open water will also largely delimit the history of Cape Bathurst Polynya. The precision with which the rate of change and duration of these paleo-climatic oscillations can be measured will be affected by the depth of cryoturbation at different sites. Cores will therefore be located using high resolution multibeam and seismic reflection profiles to obtain decadal-centennial records. Improved correlations between environments and algal production (subproject 2.7) will refine paleo-salinity and - productivity estimates and the importance of shoreline thermokarst basins in carbon storage will be measured.

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Canadian Principal Investigators and Canadian Collaborators:
Barber, D.G. (Professor) CEOS, University of Manitoba, MB
Diebel, D. (Professor) Memorial University, Newfoundland
Hanesiak, J. (Assistant Professor) CEOS, University of Manitoba, MB
MacDonald, R. (Research Scientist) Institute of Ocean Sciences, DFO, Sidney, BC.
Tian, R. (Post Doc) Memorial University, Newfoundland

Wassman, P. (Professor) University of Tromsø, Norway
Willmott, A. (Professor) Keele University, Keele, UK
Maslowski, M. (Research Scientist) Naval Postgraduate School, Monterey, CA
Arbetter, T. (Post Doc) CIRES, University of Colorado, Boulder, CO
Arrigo, K. (Professor) Stanford University, Stanford, CA
Biggs, N. (Post Doc) Keele University, Keele, UK
Holland, D. (Professor) New York University, New York, NY

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List of Principal Investigators (PI) in the CASES Research Network

1. Atmospheric and Sea Ice Forcing of Coastal Circulation on the Mackenzie Shelf

Ingram (Co-leader) McGill U.
Carmack (Co-leader) Inst. Ocean Sci. (DFO)
Gratton INRS-ETE
Marsden RMC (DND)
Melling Inst. Ocean Sci (DFO)

2. Ice-Atmosphere Interactions and Biological Linkages
Barber (Leader) CEOS, U. of Manitoba
DeAbreu Environment Canada
Flett Environment Canada
Papakyriakou CEOS, U of Manitoba
Ramsay Environment Canada
Yackel U. of Calgary

3. Light, Nutrients, Primary and Export Production in Ice-Free Waters
Demers (Leader) ISMER, UQAR
Gosselin ISMER, UQAR
Larouche IML-MPO
Michel FWI-MPO
Poulin CMN
Price U. McGill

4. Microbial Communities and Heterotrophy
Vincent (Leader) U. Laval
Suttle U. of British Columbia

5. Pelagic Food Web: Structure, Function and Contaminants
Deibel (Leader) Memorial University
Fortier (Leader de CASES) U. Laval
Reist MPO
Stern MPO

6. Organic and Inorganic Fluxes
PR Hill (Co-leader)
Macdonald (Co-leader) ISO - DFO
Grant U. Dalhousie
PS Hill U. Dalhousie
Mucci U. McGill
Sundby U. McGill

7. Benthic Processes and Carbon Cycling
Aitken (Leader du projet) U. de Saskatchewan
Conlan Can. Museum of Nature
Gagnon Can. Museum of Nature

8. Millenial-Decadal Variability in Sea Ice and Carbon Fluxes
Mudie (Co-leader) Natural Resources Canada
Scott (Co-leader) U. Dalhousie David.Scott@Dal.Ca
Blasco Natural Resources Canada

9. Coupled bio-physical model on the carbon flows
Barber (Leader) CEOS , U. of Manitoba
Diebel Memorial University
Hanesiak CEOS, U. of Manitoba
MacDonald IOS - DFO
Tian Memorial U.  

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Natural Sciences and Engineering Research Council of Canada