Oceanic dimethylsulfide (DMS) is produced by microbes in the ocean and ventilated into the atmosphere, where it serves as a precursor for sulfur aerosols that reflects incoming solar radiation, and thus the oceanic concentration of dimethylsulfide plays an important role in regulating global climate. Our group has been conducting high resolution measurements of DMS and its related compounds DMSO and DMSP of the marine sulfur cycle in the Subarctic Pacific and the Southern Ocean, by developing sea-going membrane inlet mass spectrometry (MIMS), which reveals the spatial and temporal variability of DMS concentrations across the oceans. We have also been developing isotope labeling methods to track the production and consumption rates of the sulfur compounds in incubation experiments, which helps us understand the cycling of DMS, DMSP and DMSO.

This project aims to produce high-resolution estimates of net community production (NCP; equivalent to carbon-export on annual timescales) in the Subarctic NE Pacific, and Arctic Ocean. Using continuous ship-based measurements of O2, and Ar or N2, it is possible to derive NCP at sub-kilometre scales. A key goal of this work is to use in-situ data to derive statistical models relating NCP to commonly-measured oceanographic variables, so that NCP can be quantified at unrivaled spatial and temporal resolution. The connections between climate variability, NCP, and the ocean’s ecosystem services (e.g. fish production, CO2 sequestration) can then be investigated.

The Arctic is currently undergoing rapid climate change and processes ranging from sea ice loss, thawing permafrost, and increases in river discharge are all affecting the biogeochemistry of the Arctic Ocean. We are collecting a multi-year record of vertical profiles of the potent greenhouse gases methane and nitrous oxide across the North American Arctic Ocean. These data enable us to understand how interannual variability in gas distributions is related to changes in sea ice cover and other biological, chemical, and physical dynamics, in order to predict how greenhouse gas emissions will change in the future.  Additionally we have been collecting a year-round time-series in Cambridge Bay, Nunavut in collaboration with Brent Else from the University of Calgary, to investigate the seasonality of greenhouse gas emissions from the coastal Arctic.

We examine current trends, drivers, future trajectories and potential economic impacts of oceanic oxygen loss in the Canadian Pacific, Arctic and Atlantic Oceans, and communicate this information to a number of stake-holders in government and the marine resources sector through several specific activities:

– Synthesis of existing time-series observations

– Improve calibration of autonomous measurements

– Assess deoxygenation drivers and future projections in the NE Pacific using modelling tools

– Quantify potential economic loss in several fisheries

Phytoplankton are ubiquitous throughout the world's oceans and are a diverse polyphyletic group, specialized to different light environments. As a result, different taxonomic groups have unique pigment signatures. The objective of this project is to develop a methodology to enable high resolution measurements of phytoplankton taxonomic compositions based on underway spectral properties of surface waters. This work will facilitate rapid and easy identification of harmful algal bloom (HAB) blooms and community responses to changing environmental conditions.

Chlorophyll pigments within the reaction centers of phytoplankton photosystem II complexes absorb incoming solar radiation, which fuels photosynthesis. Light energy that is not converted to photochemical energy is competitively dissipated as heat or fluorescence. The inverse relationship between fluorescence and photochemistry enable study of phytoplankton light utilization efficiencies and gross photochemistry rates. We use active fluorescence measurements to study phytoplantkon productivity and photo-physiology across a range of diverse ocean environments.