ANNUAL POPULATION DYNAMICS OF T7-LIKE CYANOPHAGES AND THEIR HOSTS IN THE GULF OF EILAT

Cyanobacteria of the genera Synechococcus and Prochlorococcus are the numerically dominant primary producers in the oceans and contribute significantly to global primary production. They are infected by a number of different virus (phage) families, including T7-like cyanophages. Based on DNA polymerase gene phylogeny two discrete T7-like lineages, clade A and B, can be discerned. Phages from clade B encode the psbA photosystem II gene, whereas phages from clade A do not. In order to begin understanding the impact these cyanophages have on cyanobacterial mortality, we developed a culture-independent method for the identification and quantification of T7-like cyanophages based on the solid-phase single molecule polony amplification method. Using this method we found that clade B phages were at least an order of magnitude more abundant than clade A phages in Red Sea along depth profiles collected monthly during 2013. The abundances of T7-like cyanophages were positively correlated with their cyanobacterial hosts, with maximal abundances from mid-summer to mid-autumn. In addition, we will present the results of correlation analysis between the phages and physical-chemical conditions of the water column. These findings suggest that cyanophages carrying the psbA gene are more successful in the Red Sea than cyanophages from the same family that lack this gene.