Combined effects of ultraviolet B radiation and climate warming on the biological pump: a temporal and latitudinal study

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Biological cycles in the ocean can be simplified to two basic processes: photosynthesis and respiration. Photosynthesis occurs exclusively in the euphotic zone and is limited  to autotrophic organisms while respiration is a ubiquitous process occurring throughout the water column. The balance between both processes on the global ocean scale is still under debate. Variation in CO2 fluxes, climate warming and increasing ultraviolet B radiation (UVBR, 280-320 nm), which strongly influence photosynthesis and respiration in the upper layer of the oceans, are presently three main concerns in the international scientific community. These factors can act synergistically on marine plankton communities, thereby modifying the dynamics of carbon fluxes between surface waters and the deep ocean. The present project examines the combined effects of climate warming, increasing CO2 and UVBR on the planktonic community and on how the resulting modifications in the planktonic system  affect atmosphere-ocean CO2 fluxes and water chemistry. The originality of this project resides in the fact that we propose a bi-polar and inter-hemispheric study of a key process -the biological pump- considering together the effects of  global significant parameters on the structure and dynamics of the whole plankton community. The special opportunity behind this research proposal resides in a combination of four inter-dependent events taking place in the next three years: (1) a cruise from Canada to Antarctica in 2005-06 (and overwintering in Antarctica in the vicinity of the Argentinean station Melchior) on board the Sedna IV, a 51m Canadian steel hull ship that has previous work experience in polar waters; (2) the availability of an Argentinean icebreaker (Almirante Irizar) for one mission in Antarctica in 2007; (3) a Cooperative Research Network (CRN) hopefully to be supported by the Inter-American Institute for Global Change Research (IAI), that would include work in the Canadian Arctic and in Antarctica; and (4) the International Polar Year (IPY) in 2007.