Our research is focusing on phage (phage= virus that infect bacteria) ecology in different aquatic environments, ranging from the open ocean, the Baltic Sea, deep subsurface environments and freshwater systems. We investigate the phage community and their interactions with their microbial hosts using sequencing of isolated phage-bacteria model systems, metagenomic sequencing and are moving towards transcriptomics. Through our research we expand our knowledge regarding previously unknown phages regarding their genetic diversity, evolution, metabolic potential and interactions with their hosts. Through long-term sampling of the viral community in the Baltic Sea we are able to investigate the temporal dynamics of both isolated phages as well as the major, uncultured part of the viral community. Further, the metagenomes provides important information on the metabolic potential of phages in the different investigated environments: a potential that is expressed while the phages replicate within their hosts. This is further investigated within our ongoing and future transcriptomic experiments.