Abstract
Viruses exert an impact on the ecology and biogeochemical cycling of all areas of the oceans examined thus far making them an important functional group in marine ecosystems. Ecosystem functioning relies on the microbial food web and specifically on primary productivity. Viruses are mortality agents that directly affect productivity, diversity and the system?s regenerative capacity. Despite these general facts, very little is known of the role of viruses in the Southern Ocean in relation to the key players of the microbial community, bacteria and phytoplankton. Moreover, virtually no data is available pertaining to the relative abundance, distribution, activity and significance of marine viruses at one location over the seasonal cycles of the Antarctic. We propose to alleviate this paucity in our knowledge by a mechanistic and comprehensive study during the production period of Austral spring to early autumn in the waters of the western Antarctic Peninsula. These coastal waters are characterized by high productivity and markedly seasonal phytoplankton blooms which drive the ecology of the habitat. They serve as a nursery ground for krill, a key species in the Antarctic food chain. The area is of special interest as it is one of the three areas of the globe experiencing rapid climate change, with already noticable alterations in phytoplankton community structure.Viral dynamics in relation to their microbial hosts will be studied in line with the relative importance of viruses as a mortality source compared to grazing, which was traditionally considered as the regulator of Southern Ocean food webs. In addition, we will examine the influence of viral infection on host fatty acid composition, a key determinate of food quality and therefore of ecosystem productivity. In order to determine the potential influence of global anthropogenic perturbations in this rapidly changing environment we will conduct laboratory experiments to asses the impact of predicted changes in light availability, salinity and pCO2 on the ecology of phytoplankton and their viruses. This timely research will establish crucially needed baseline measurements of key ecological processes in an early warning site of global change (and therefore highly scientifically, societally and politically relevant), and thus provide valuable data for modeling and prediction of future consequences of anthropogenic perturbations of climate composition.
Netherlands