In the Xiangxi River in August 2004 (rainy season),
27 genera (39 taxa) were recorded, belonging to 18
families (Table 2). Taxa composed diatom, chlorophyta,
cryptophyta, cyanophyta and pyrrophyta; chlorophyta
accounted for the most taxa (51%). In April
2005 (dry season), 26 genera (39 taxa) were identified,
belonging to 16 families. In additional to the five
major phytoplankton groups recorded in August,
chrysophyta were also reported in April (Table 2).
Diatoms accounted for 56% of the total taxa. Numbers
of cyanophyta taxa were 2 in the rainy season and 1 in
the dry season.
In August 2004 (rainy season), an algal bloom
(density>106 cells·l− 1) occurred in the Xiangxi River
and the influx region of the Yangtze and Xiangxi. The
dominant species was Chroomonas acuta with the
maximum density appeared at station A1, and high
values were also recorded at stations A2 and A3. At
station A3, the total abundance of chlorophyta reached
1.12×106 cells·l− 1 (Fig. 2).