Projectdetails

Microbial communities (phytoplankton, bacteria, archae, heterotrophic protozoa and viruses) comprise the majority of the biomass in the oceans and drive nutrient and energy cycling, thereby supporting also the polar ecosystems. The emergent awareness that the response of ecosystems to climate change depends largely on the responses of the underlying microbial community, that phytoplankton productivity is of vital importance to the global climate system, and that viruses are major players influencing biodiversity and biogeochemical processes, underlines the need to elucidate the ecological role of viruses in polar ecosystems. Despite the likely importance of viruses in polar aquatic ecosystems, the ecological role of viral mediated mortality of polar microbes (and phytoplankton in particular), and the quantitative significance of polar viruses with respect to climate and global environmental change are barely studied. The present project will be the first comprehensive study to focus on viruses and viral mediated processes in polar environments. As part of the Polar Aquatic Microbial Ecology (PAME) IPY activity program, this project?s objectives are 1) To examine the abundance and composition of viruses and their host (prokaryotes and phytoplankton) in bipolar marine environments, 2) To compare the significance of viruses and their impact on microbial mortality and geochemical cycling in the aquatic polar ecosystems (Arctic vs. Antarctic), and 3) To unravel the impact of climate and global environmental change on the ecological role of viruses and their activities. Particular efforts in the presently proposed activities will focus on viral mediated mortality of phytoplankton, the group of organisms that form the base of each pelagic food webs. In order to clarify the ecological importance of viruses for the polar ecosystems an integrated study assessing the presence, meaning and functionality of virus and host in the field is planned in combination with laboratory research exploring the effect of climate change related environmental factors on virus-host interactions (specifically of the relevant polar phytoplankter Micromonas pusilla). Both the Arctic and the Antarctic seas are key regions in the ocean?s circulation and are considered sensitive to global warming. The global change-induced environmental changes will directly impact the polar microbial community and most likely enhance the significance of viruses. The results of this timely proposed project will largely advance our comprehension of the importance of viruses for the functioning and biodiversity of the polar marine microbial ecosystems. The results are expected to provide new insights in our understanding of the structure of polar marine pelagic food webs and geochemical cycling, as well as to what extent both polar regions are different. The obtained data will, furthermore, be essential for a more accurate evaluation of global carbon cycle models.