Dr. Uta Passow
Canada Research Chair in Biological Oceanographic Processes
Research involves: Impact of climate change and contaminants on the biological carbon pump.
Research relevance: This research will increase our understanding of the impacts of climate change and oil or plastic pollution on marine ecosystems and allow development of mediating measures.
Signs of human activities mark the deep ocean
What do rising atmospheric carbon dioxide concentrations, oil spills and plastic pollution have in common? Anthropogenic carbon, spilled oil and plastics may all end up at the seafloor, where their presence is unexpected. Carbon is transferred against a concentration gradient, oil and plastics are positively buoyant and usually believed to accumulate at the seasurface. But the biological carbon pump may transport carbon, and these contaminants down to depth. Because tiny marine organisms like one-celled algae, or feces, molts and other detrital particles form marine snow, as the dust bunnies of the ocean are called, they sink towards the deep sea carrying carbon, and contaminants like oil droplets or micro-plastics with them. Once at depths > 1000 m, carbon and incorporated substances are removed from the surface ocean and the atmosphere for hundreds of years. The combination of these processes are referred to as the biological carbon pump. Since the industrial revolution 30 per cent of anthropogenic carbon has been sequester by the deep ocean and a similar fraction of oil spilled during Deepwater Horizon (2010) reached the sea floor.
The removal of carbon from the atmosphere via the carbon pumps and the sequestration by the deep sea, reduces the increases in global temperature, but leads to ocean acidification. This reduction in pH, combined with the direct and indirect effects of global warming, impacts marine productivity and alters marine ecosystems, impacting fisheries and reducing recreational activities at coral reefs.
Increased drilling activities in Arctic waters make an oil spill in cold oceans one of the main concerns of emergency response teams. Like oil, tiny plastic particles float, but may be transported to depths when incorporated into marine snow. It is important to understand distribution pathways of oil or plastics in marine ecosystems to evaluate their impact. Consequences of contaminants differ if they are transported to the seafloor or moved with currents at the sea surface.
This research will help predict ecosystem changes due to anthropogenic impacts and aid in the development of response and mediating measures to the expected changes.