Seasonal changes and electronmicroscopic features of marine virus isolated from Gwangyang bay

Abstract

Seasonal distributions of the viral abundance and physicochemical parameters were analyzed at three different regions in Gwangyang Bay. Also morphological structure of marine virus was observed using transmission electron microscopy. Most of marine virus had bacteriophage-like structure, but some were similar with eukaryotic microalgal viruses, Ectocarpus siliculosus virus (EsV). Viral abundance at Group 1 (closed eutrophic region) was higher than viral abundances at Group 2 (closed oligotrophic region) and Group 3 (open oligotrophic region). Seasonal abundances of marine virus at Group 1 were dynamically changed. The viral density was variably changed from maximum 7.33×108 ml-1 in August to minimum 0.3×108 ml-1 in December and maintained middle value in spring and autumn. The concentration of nitrogen and phosphate sources was correlated with viral abundance. Particularly, seasonal change of dissolved oxygen concentration was opposite to the variation of viral abundance. Results showed that viral abundances were closely related with fluctuation of marine physicochemical environment in Gwangyang bay.