Abstract
Algal blooms have been frequently found at the upper reaches of the Tanglang River, which is downstream from the eutrophic Dianchi Lake. The eutrophic lake upstream is considered to be a potential source of phytoplankton, which contributes to the development of harmful algal blooms in the river downstream and can cause many serious problems for the river ecology. However, few studies focused on these kinds of rivers. Therefore, a field observation and laboratory analysis were conducted in this study. The results showed that the Tanglang River was obviously spatially heterogeneous due to the eutrophic Dianchi Lake upstream. The toxic Microcystis from the Dianchi Lake dominated the phytoplankton at the upper reaches, but these were gradually, rather than immediately, replaced by centric diatoms and chlorococalean green algae in the middle and lower reaches. The results of correlation analysis indicated that the changes in hydrodynamic conditions and underwater light intensity accounted for the spatial variations. The differences in the adaptability of different algae to changing aquatic environments explained the spatial variations of phytoplankton abundance. The dominant algae, most of which was from the Dianchi Lake upstream, determined the characteristics of the total abundance at the Tanglang River.
Highlights
Algal blooms have become a frequent sight in the upper reaches of the Tanglang River during the past few years [1]
In high-bloom seasons, the surface blue-green scums can stretch a long distance in the river downstream [1]
Physical and Chemical Variables In Dataset1 (Table 1), the highest water temperature (WT) in the Pudu River was observed in August (September) 2010 with an average temperature of 22.16 °C and this temperature was 6.8 and 7.4 °C higher than the temperatures measured in March 2011 and November 2010, respectively
Summary
Algal blooms have become a frequent sight in the upper reaches of the Tanglang River during the past few years [1]. In high-bloom seasons, the surface blue-green scums can stretch a long distance in the river downstream [1] This phenomenon is rare elsewhere in rivers because the initial inoculum of phytoplankton at the beginning of rivers is usually small [2]; as a result, most often, blooms occur only in the middle or lower reaches of large, nutrient-rich rivers [3,4,5]. The cause of this unusual phenomenon is the upstream eutrophic Dianchi Lake, which may supply a large amount of dominant lacustrine algae to the river downstream.
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