Factors determining variations in viral abundance and viral production in a tropical estuary influenced by monsoonal cycles

Abstract

Abstract Viruses are the most abundant, dynamic, and ubiquitous components in the marine and estuarine environments. They outnumber prokaryotes in their abundance by at least one order of magnitude, but their relationship varies across environments. The present study examined the environmental factors (temperature, salinity, inorganic nutrients, and host abundance) that influence abundance and distribution of viruses in a tropical monsoonal estuary (Cochin estuary — CE) in India. Water samples were collected daily for one year from two stations with different hydrological settings in the estuary. Virioplankton abundance (VA) fluctuated daily with no definite pattern, but synchronized with the variations in prokaryotic abundance. On a seasonal scale, the abundance of virus and prokaryotes were higher during the summer months (pre-monsoon period) compared to monsoon and post-monsoon. The temporal dynamics of virioplankton was influenced by prokaryotic abundance (PA), viral production (VP), temperature, salinity and nutrient concentrations. The viral to prokaryote ratio (VPR) ranged from 1–44. There were significant (p