Biogeochemistry of trace metals in Canada's subarctic and Arctic oceans under a rapidly changing climate

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The oceans provide ecosystem services that benefit all Canadians but these services are increasingly threatened by human activity. Two of these services at risk are the sequestration of atmospheric carbon dioxide through photosynthesis, which helps to mitigate climate change, as well as the production of food through our fisheries. Photosynthetic marine microbes provide these services because they consume CO2 and form the base of the marine food web. As a maritime nation, understanding what controls the growth of marine microbes and thereby the services the marine environment provides has clear economic and cultural relevance for Canadians. Trace metals are elements that are found in very small concentrations in seawater either because they are rare on our planet or because they are rapidly removed from the ocean by chemical and/or biological processes. The amount and chemical form of trace metals in seawater can prevent photosynthetic microbes from growing either because they are essential limiting nutrients, or they are toxins when too abundant. Ultimately, metals can control the oceans ability to take up greenhouse gases and slow climate change. Similarly, the health and sustainability of our fisheries can depend on the biological availability of metal nutrients and toxins. So, while trace metals are not abundant in the ocean they have impacts that are much greater than their small concentrations might suggest. My research group develops and uses highly sensitive analytical tools to study trace metal chemistry in the ocean. The long-term goals of my research program are to understand the processes that control the distribution, chemical form and resulting availability of trace metals to microbes, and how climate change is likely to impact trace metal chemistry in the future. We focus on metals that control primary production and microbe community structure (e.g. iron, copper and zinc), serve as paleoceanographic tracers that provide important information regarding the oceans role is past climate change (e.g. silver, cadmium), or potentially toxic heavy metals that might negatively impact the marine ecosystem (copper, silver and cadmium). Over the next 5 years my short term research objectives are to: 1) examine how changing temperature, ocean acidification and light where sea ice melts in high latitude ocean surface waters will impact biologically important metals; 2) unravel how much metals are either added or removed from the ocean near the continents; and 3) determine how decreasing oxygen levels in the ocean impact the relative distribution of metals. Our data will allow for better incorporation of metal chemistry in computer models designed to predict the response of marine services that benefit Canadians to climate change. This understanding will allow policy makers to make effective plans to moderate and mitigate ongoing human caused climate change and to sustainably manage and steward our marine resources into the future.