CASESCASES Canadian Arctic Shelf Exchange Study

Objectives

Based on the general hypothesis that the atmospheric oceanic and hydrologicBased on the general hypothesis that the atmospheric, oceanic and hydrologic forcing of sea ice variability dictates the nature and magnitude of biogeochemical carbon fluxes on and at the edge of the Mackenzie Shelf, the major objectives of CASES are to assess:

• The role of hydrologic, oceanographic and meteorological processes in ice growth, decay and transport on the shelf and beyond. • The hydrodynamic (including ice and snow cover dynamics) control of Arctic shelfThe hydrodynamic (including ice and snow cover dynamics) control of Arctic shelf photosynthetic production and its export to the benthos and the pelagic food web. • The potential impact of increased UV radiation on biological productivity. • The role of microheterotrophs and mesozooplankton in transforming particulate and dissolved matter on the shelfand dissolved matter on the shelf.• The fluxes of particulate matter and carbon across the shelf to the deep basins.• The distribution of riverine and air-borne contaminants in the trophic web.• The potential impact of a reduction in ice habitat on birds and marine mammals.

Th d d l d ill i l i ti i i d th i i t t• The decadal and millennial variations in ice cover and their impact on ecosystem productivity.• Physical and biological measurements will also be used to constrain and calibrate: regional models of climate and ice dynamics in the western Canadian Arctic as well as biophysical models of the carbon flows on the Canadian Arctic shelf.

The general working hypothesis was that the atmospheric, oceanic and hydrologic forcing of sea ice variability dictates the nature and magnitude of biogeochemical carbon fluxes on and at the edge of the Mackenzie Shelf

The science program comprises 9 subprojects.

1. Atmospheric and Sea Ice Forcing of Coastal Circulation2 I At h I t ti d Bi l i l Li k2. Ice-Atmosphere Interactions and Biological Linkages3. Light, Nutrients, Primary and Export Production in Ice-Free Waters4. Microbial Communities and Heterotrophy5 Pelagic Food Web: Structure Function and Contaminants5. Pelagic Food Web: Structure, Function and Contaminants6. Organic and Inorganic Fluxes7. Benthic Processes and Carbon Cycling8 Millenial-Decadal Variability in Sea Ice and Carbon Fluxes8. Millenial Decadal Variability in Sea Ice and Carbon Fluxes9. Coupled bio-physical models of the carbon flows on the

Canadian Arctic Shelf

Resolute, Sept 23 2003

Tuktuyaktuk, Sept. 30, 2003 Sept. 23, 2003

Quebec City, Sept. 13, 2003

Expedition planExpedition plan

ΣCO2 = DIC = [H2CO3*] + [HCO3-] + [CO32-]

pH = -log (H+)

Titration alkalinity = At = [HCO3-] + 2[CO32-] + [B(OH)4-] + ΣB-

Average fCO2 (µatm) in the surface mixed layer (0-15 m) calculated from pH, At and DIC measurementsg 2 (µ ) y ( ) p ,carried out on Legs 1 and 2 (late September through early December, 2003).

Average fCO2 (µatm) in the surface mixed layer calculated from pH, At and DIC measurements carriedout on Leg 8 (July, 2004).

Canadian IPY Programg• Total of 44 science projects funded during the

IPYIPY• $150M IPY Program overall• Vessel Based projects Pacific Sector• Vessel Based projects – Pacific Sector

1. Canada’s Three Oceans (C3O) – Carmack/IOS2 GEOTRACES Francois/UBC2. GEOTRACES – Francois/UBC3. Carbon Cycle – Gobeil/INRS-ETE4 Circumpolar Flaw Lead (CFL) Barber/UManitoba4. Circumpolar Flaw Lead (CFL) – Barber/UManitoba5. Trace Gases – Levasseur/Laval+ MALINA Babin/Villefranche sur Mer France+ MALINA – Babin/Villefranche-sur-Mer, France