Phytoplankton variation and its relationship with the environment in Xiangxi Bay in spring after damming of the Three-Gorges, China

Abstract

Following the completion of the ThreeGorges Dam, there was a strong spring phytoplankton bloom in Xiangxi Bay of Three-Gorges Reservoir. However, our knowledge of relationship between spring phytoplankton bloom and environmental factors was still limited. In this study, phytoplankton species composition, biomass, chlorophyll a concentration and environmental factors at two sampling sites in Xiangxi Bay were investigated during 25 March to 18 May 2007. The Xiangxi Bay was eutrophic with the lowest values of total nitrogen and total phosphorus being 0.80 and 0.07 mg/L, respectively. A total of 66 algal taxa belonging to seven phyla and 45 genera were identified. Peridiniopsis niei Liu was the most abundant species which preferred standing water. Canonical correspondence analysis and correlation analysis revealed that nitrate was significantly associated with phytoplankton growth. The phytoplankton chlorophyll a concentration was correlated significantly negatively with nitrate concentration, and nitrate concentration was very low during bloom periods. Heavy rainfall was the main reason of phytoplankton chlorophyll a concentration and biomass decreasing and blooms disappearing. In addition, heavy rainfall also brought more nitrate into the Bay which provided sufficient nitrogen source for blooms occurring again.

The spatial pattern of larval fish assemblages in the lower reach of the Yangtze River: potential influences of river–lake connectivity and tidal intrusion

“…The Secchi depth (cm) was measured using a Secchi disk. Phytoplankton was collected by sampling 1-l surface water with a plastic bottle, fixed with 1% Lugol's iodine (15 ml) and 4% formalin (5 ml) solutions (Zhou et al, 2011). Zooplankton (50 l) was collected using a self-made water sampler (5 l), filtered with a 64-lm mesh net and preserved in the 4% formalin solution.…”

Responses of phytoplankton functional groups to the hydrologic regime in the Daning River, a tributary of Three Gorges Reservoir, China

“…The phytoplankton in TGR has been extensively studied, especially the seasonal variation in phytoplankton species (Zeng et al, 2006;Zhou et al, 2011), algal blooms (Wang et al, 2011b;Ye and Cai, 2011), eutrophication (Zheng, 2007;Zhong et al, 2005), and the relationship between biotic and abiotic factors (Bi et al, 2010;Zhang et al, 2010).…”

Impacts of the Three Gorges Dam on microbial structure and potential function

“…For example, the water level has increased more than 40 m; the water flow velocity has dropped significantly23; and water blooms have been detected in spring at some newly formed bays2425. Although phytoplankton succession and the process underlying blooms in the Xiangxi River have been frequently studied242526, our understanding of damming effects on planktonic microorganisms is largely restricted to phytoplankton shifts and related environmental changes, while changes in bacterioplankton have been largely ignored.…”