Small hydroelectric power plants (HPPs) with a capacity of up to 30 megawatts (MW) and reservoirs of up to 13 square kilometers can alter the composition of macroinvertebrate and fish species, according to an analysis of the impact of 12 small HPPs along the Chapecó and Chapecozinho rivers in Santa Catarina. Researchers from Brazil and the USA found that fast-flow organisms were being replaced by others from stagnant waters, such as the pearl cichlid (Geophagus brasiliensis), the abundance of which increased by up to four times. “The perception that small HPPs have a low environmental impact has no basis in reality,” notes biologist Thiago Couto, the lead author of the study, who is doing a postdoctoral fellowship at the University of Washington, USA. The authors point out: “Environmental impact studies should pay special attention to the characteristics of the location and the cumulative effects of the small hydroelectric system, rather than the structural aspects.” According to the Brazilian Electricity Regulatory Agency (ANEEL), 219 large HPPs and 1,164 small HPPs are operating in Brazil, including 425 small plants that generate between 5 and 30 MW, and 739 micro plants that generate up to 5 MW (Freshwater Biology, April 7).
Christoph.fr / WikimediaThe pearl cichlid reproduces more successfully in still watersChristoph.fr / Wikimedia
