grazing by protists ~50%: lysis due to bacteriophage ~50% %
||Young KD. The selective value of bacterial shape. Microbiol Mol Biol Rev. 2006 Sep70(3):660-703 DOI: 10.1128/MMBR.00001-06 p.684 right column 2nd paragraphPubMed ID16959965
|| Fuhrman, J. A., and R. T. Noble. 1995. Viruses and protists cause similar bacterial mortality in coastal seawater. Limnol. Oceanogr. 40: 1236-1242 link  Suttle CA. Viruses in the sea. Nature. 2005 Sep 15 437(7057):356-61 DOI: 10.1038/nature04160 PubMed ID16163346
||Primary source  abstract: "Mesocosms filled with 80 liters of coastal seawater from Santa Monica, California, were used twice (June and November) to budget bacterial production and loss, as well as to assess the relative significance of viral lysis and protist grazing in bacterial mortality."
||P.684 right column 2nd paragraph: "Overall, the best guess for bacterial mortality in the open ocean is approximately 50% from grazing by protists and 50% from lysis due to bacteriophage (primary sources)."