PLoS ONE: Assessing the Diversity and Specificity of Two Freshwater Viral Communities through Metagenomics | Virology News | Scoop.it
From www.plosone.org - March 24, 2012 9:06 AM

Transitions between saline and fresh waters have been shown to be infrequent for microorganisms. Based on host-specific interactions, the presence of specific clades among hosts suggests the existence of freshwater-specific viral clades.