Quantifying Rates of Biological Production to Better Understand the Carbon Cycle in the Canada Basin
In order to predict the future carbon cycle in a rapidly changing Arctic Ocean, a better understanding of the present-day carbon cycle is needed, and this research will study this with some relatively novel methods. The gas tracers oxygen, argon and triple oxygen isotopes can be used to quantify rates of net community production and gross primary production, respectively. Net community production is defined as photosynthesis minus community respiration and thus reflects the net amount of CO2 taken up by the ‘biological pump.’ Gross primary production is defined as the total photosynthetic flux. The ratio of net community to gross primary production yields information on how tightly an ecosystem is recycling its carbon. By concurrently measuring rates of net community and gross primary production, this work will study the environmental effects on photosynthesis and respiration, and this should allow a better mechanistic understanding of the processes controlling biological production. This research will use the ratio of O2 to Argon and triple oxygen isotopes to quantify rates of biological production on summertime cruises for three years in the Beaufort Gyre section of the Canada Basin. The main objective of this work is to gain a better understanding of the interplay among biological production, sea ice, and temperature in the Canada Basin. The team will use data collected in 2011 and 2012, collect samples in 2013 and interpret all the data in order to address two hypotheses. The first is that gross primary production increases when summer sea ice extent is smaller but that net community production does not change. In this case there will be no net change in the carbon cycle although production will seem elevated if one uses traditional metrics of chlorophyll or biomass. The second hypothesis is that rates of gross primary production and carbon recycling are higher in regions of actively melting ice that is in ‘ice edge blooms.’ These ice edge blooms should have similar rates of net community production to the open water and be responsible for no additional net carbon uptake. Broader Impacts - Professional media designers will produce a short video about changing biological productivity in the Arctic Ocean. This will be shown at the Woods Hole Oceanographic Exhibit Center and on local ferries to Martha’s Vineyard. Additionally, this project will promote education by including opportunities for a graduate student.