Spatiotemporal dynamics of the total and active Vibrio spp. populations throughout the Changjiang estuary in China.

Vibrio is ubiquitously distributed in marine environments and is the most extensively characterized group within Gammaproteobacteria. Studies have investigated Vibrio spp. worldwide, but mostly focused on pathogenic vibrios and based on cultivation methods. Here, using a combination of molecular and culturing methods, we investigated the dynamics of the total and active Vibrio spp. throughout the Changjiang estuary in China. The total Vibrio abundance was higher in summer (~6.59 × 103 copies ml-1) than in winter (~1.85 × 103 copies ml-1) and increased from freshwater to saltwater (e.g. 8.04 × 101 to 9.39 × 103 copies ml-1 in summer). The ratio of active to total Vibrio (Va/Vt) revealed a high activity of vibrios, with remarkable differences between freshwater and saltwater (p < 0.05). Based on the community compositions of the culturable, total and active Vibrio, Vibrio atlanticus and Vibrio owensii were the dominant and active species in winter and summer, respectively. The distribution of Vibrio was governed by the effects of diverse environmental factors, such as temperature, salinity, pH, dissolved oxygen and SiO3 2-. Our study clearly demonstrates the spatiotemporal dynamics of total and active Vibrio spp. and lays a foundation for fully understanding the ecological roles of marine Vibrio.