VIRARCT_Importance of microbial viral lysis over grazing in a changing Arctic Ocean

Microbial communities comprise the majority of the biomass in the oceans and drive nutrient and energy cycling, thereby supporting also the polar ecosystems. The Arctic Ocean ecosystem is expected to undergo major climate change related transformations in the coming decades.

Recent data indicate that the future Arctic Ocean will experience a shift at the base of the food web towards small-sized phytoplankton, which will lower the efficiency of the Arctic ecosystem. Viruses are expected to be important mortality agents specifically for these smaller-sized phytoplankton, thereby stimulating the microbial food web, diminishing transfer of organic matter to higher trophic levels and reducing the biologically-driven CO2 sequestration in the deep ocean.

Viral impact on microbial interactions

The proposed project will study temporal variation in Arctic marine microbial interaction, and more specifically the importance of viral lysis over grazing, in relation to host community composition. Additionally, we will study the influence of fine sediments in glacier outflow on virus-host interactions. In order to clarify the effect of changing environmental conditions on the microbial interactions in these ecologically important waters, the influence of combined environmental changes (e.g. temperature and salinity, light) will be studied using 2 small-sized phytoplankton model species in the presence and absence of host-specific viruses. This timely study is primed to deliver essential data for ecosystem modeling, provide a solid base for future studies, and contribute to predictions of ecological relevant shifts in key players and ecosystem productivity as a result of global climate change.