Temporal impacts of a small hydropower plant on benthic algal community

To explore the temporal impacts of a small hydropower plant (SHP) on benthic algal community, monthly samples from November 2005 to June 2006 were taken in a reach of the Xiangxi River, China. During the study period, a total of 116 taxa were recorded and diatoms were the most abundant group, accounting for 60.42 % of total taxa. Our study showed that operation of the SHP had significant impacts on river systems: (1) distinct physicochemical conditions between control and impaired sites; (2) remarkable increase of chlorophyll-a concentration, total algal densities, and decrease of Shannon-Wiener diversity index, evenness at impaired sites during the dry period (e. g., November, December, January, February and March); (3) profound impacts on overall benthic algal community in dry periods (e. g., November, December, January, February, March, May and June). However, the rainfall or the periodical connectivity of channel appeared to decrease the impacts of the SHP on the benthic algal community (e. g., April and May). We suggest that a minimal discharge should be preserved during the dry period and a basal flow kept for the maintenance of fluvial connectivity of the river water, which would provide more sustainability to the benthic algal community as well as other aquatic organisms.