Functional bacteria as potential indicators of water quality in Three Gorges Reservoir, China

Abstract

The distributions of culturable bacteria and functional bacteria associated with nitrogen (N) or phosphorus (P) in the backwater areas of the Three Gorges Reservoir (TGR) were investigated. Results from seven locations in the TGR indicated that the abundance of total bacteria was high, with 8.12 x 10(6), 2.70 x 10(7), and 6.73 x 10(10) colony-forming units per milliliter or per gram dry weight in surface water, bottom water, and sediments, respectively. Aquatic environments with higher nutrient loadings possessed higher bacteria densities and lower bacteria community diversities. Eight kinds of functional bacteria ratios, including surface water to bottom water and ratios of water to sediments, were calculated, in which four kinds of functional bacteria, namely, nitrogen-fixing bacteria, ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, and organophosphate-solubilizing bacteria, displayed obvious differences in different locations. Based on the functional bacteria ratios of water to sediments, it was found that the obtained result of location grouping from cluster analysis was similar to that based on the community-level physiological profiles studies. The above results showed that the ratios of functional bacteria could distinguish the aquatic environments with different trophic conditions in the TGR. This demonstrated that the distribution ratios of functional bacteria in aquatic environments could work as potential bioindicators to reflect the trophic condition of the water.

Artificial tide generation and its effects on the water environment in the backwater of Three Gorges Reservoir

“…This phenomenon is commonly considered a major contributor to global environmental degradation (Nixon, 1995;Wang et al, 2010). TGR, which is the largest hydropower complex project in the world, is located in the middle reach of Yangtze River in China (Wu et al, 2003;Shen and Xie, 2004;Müller et al, 2008).…”

“…As a result, the phytoplankton may grow quickly. Algae blooms were frequently observed in the backwater area during spring and autumn over the recent years (Yan et al, 2008;Wang et al, 2009Wang et al, , 2010. The eutrophication in the TGR bays became a major environmental problem that attracted increasing attention from other parts of the world.…”