5×10^6 - 15×10^6 viruses/ml
||Bergh O, Børsheim KY, Bratbak G, Heldal M. High abundance of viruses found in aquatic environments. Nature. 1989 Aug 10 340(6233):467-8. p.467 left column bottom paragraphPubMed ID2755508
||P.467 left column bottom paragraph: "The highest total counts of viruses and bacteria were found in samples from the eutrophic lake Plussee (Table 1). [Investigators] found total counts of viruses of between 5×10^6 and 15×10^6 per ml in marine samples taken during the productive part of the year."