Arctic Science Northwest Passage Project science: How is the warming trend in the Arctic affecting waters of the Canadian Arctic Archipelago?

Scientists tread ice and snow. Canada Basin of Arctic. Credit NOAA Jeremy Potter

The science activities of the Northwest Passage Project (NPP) are motivated by the overarching goal of understanding how waters of the Canadian Arctic Archipelago (CAA) have changed as a consequence of the warming trend over the Arctic Circle. Project scientists will approach this goal using an interdisciplinary, ocean-based research program, deploying a variety of oceanographic instruments during the ship’s transit in the Northwest Passage.

The CAA, and particularly the Northwest Passage, is one of the principal conduits for freshwater transport from the Arctic Ocean to the North Atlantic.

While the Arctic provides a multitude of research opportunities, this expedition seeks specifically to fill chronic data gaps in four (4) thematic areas:

  • Water mass properties and circulation inside CAA
  • Water column chemistry affecting greenhouse gas fluxes
  • Microscopic communities in transition
  • Distributions of marine birds in Canadian Arctic Waters

Water mass properties and circulation inside the Canadian Arctic Archipelago (CAA)

The project will investigate the increased freshwater storage in and export from the upper Arctic Ocean due to a warming Arctic. Increased melting, river discharge, as well as changing wind patterns have led to increased freshwater accumulation in the western Arctic. The CAA, and particularly the Northwest Passage, is one of the principal conduits for freshwater transport from the Arctic Ocean to the North Atlantic, however, there are uncertainties in the magnitude of transport and water properties.

The currents in the CAA will be studied with data collected by a Lowered Acoustic Doppler Current Profiler (LADCP) and a Current, Temperature, and Depth Profiler (CTD). NPP will conduct Shore-to-shore CTD/LADCP cross-sections at locations marked on the cruise track. These will involve high-resolution CTD casts to resolve water mass properties along with the CTD rosette mounted LADCP.

Water column chemistry affecting greenhouse gas fluxes

The concentration and isotopic composition of methane and carbon dioxide in the Arctic Ocean and atmosphere are of great interest as both are greenhouse gases and have growing sources in the Arctic. The sources and flux of both between the ocean and atmosphere are important components of the global climate system. The Arctic Ocean generally absorbs carbon dioxide, but ice cover limits air-sea exchange. Measuring isotopic composition of carbon dioxide can provide information about the carbon system sources and fluxes of carbon to the atmosphere.

Methane, a more potent greenhouse gas than carbon dioxide, is found throughout the Arctic Circle, and the Arctic appears to be an ever growing source of methane to the atmosphere. Methane is found in land-based permafrost and as methane ice or methane hydrates, which are distributed along the seafloor. With less sea ice cover, there can be an increased flux of methane into the atmosphere from the ocean.  However, some microbes in ocean water use methane as a food source.  If microbial breakdown of methane is rapid enough, it may serve to offset the methane that escapes to the atmosphere. There is little data to provide estimates of this methane breakdown in Arctic water. The Northwest Passage Project will study the concentrations and isotopes of carbon dioxide and methane by analyzing samples of the air and water with onboard laser spectroscopy instruments, as well as incubation of water to study methane consuming microbial activity.

Seawater will be continuously sampled from the underway seawater system and from discrete bottle samples taken from the water column with the CTD rosette. Additional analysis of the underway seawater and bottle water samples will include salinity, temperature, chlorophyll a fluorescence, colored dissolved organic matter (cDOM) fluorescence, partial pressure of carbon dioxide (pCO2), pH, the δ18O of seawater, particulate organic carbon and nitrogen (concentration and isotopic fractionation), nutrients (NO3, PO4, and Si(OH)4). Opportunistic sampling of floating ice will also be carried out.

Microscopic communities in transition

As Arctic waters warm and sea ice cover decreases, the surface ocean ecosystem is changing, and species distributions and abundances may change rapidly. To examine habitats along the cruise track, zooplankton nets will be periodically towed in the upper water column (≤100m). Net contents will be catalogued. This data will be augmented by a laboratory bench-top FlowCam, which can identify and quantify ‘particles’ in seawater which can be sediments, phytoplankton, or zooplankton. Additional samples of the micro-organisms in the water will be collected from CTD rosette bottle. In addition, a high-frequency sonar system will observe zooplankton and fish in the water column. Combining these approaches to ecosystem studies will make the results more robust.

Courtesy of Vancouver Maritime Museum.

Distributions of marine birds in Canadian Arctic waters

Marine bird abundance and distribution can be used to monitor changes and variability in marine ecosystems. The Northwest Passage Project will characterize the distribution and abundance of marine birds along the survey route. Associations between the marine bird community and the physical and biological properties of their marine environment will be identified and compared to past results. The cruise will use a standard non-invasive, observational method to perform seabird counts.

 

Open Data Policy

The project will disseminate scientific data and results through the Northwest Passage Project website. All processed measurements will be stored in the NSF-supported Arctic Data Portal and all appropriate Canadian and Inuit science databases.