Influences of Small Hydroelectric Plants on the genetic differentiation of Neotropical freshwater fish populations: a case study

In view of the growing global demand for electricity, many countries have been looking for ways to diversify production. However, in countries such as Brazil, hydroelectric power plants still constitute the predominant generating source, occupying important drainage systems, such as the Upper Parana River. At the same time, hydroelectric dams are among the main sources of impacts on freshwater fish, interfering, for example, in the genetic distribution of populations. Although the same could be expected from Small Hydroelectric Plants, very little genetic information has been obtained along Neotropical drainages. Based on this, the present study analyzed the DNA (microsatellite loci) of non-migratory fish species (seven) upstream and downstream of three Small Hydroelectric Plants in the Upper Parana River basin, obtaining information about the genetic distribution of fish populations in this scenario. In general, the data suggest that populations have been genetically subdivided by Small Hydroelectric Plants and that other factors, such as the number of Small Hydroelectric Plants along a drainage and connectivity with long free stretches, could also influence genetic differentiation levels, which provides information of great relevance to global discussions about the impacts of hydroelectric power plants, as well as for the implementation and management of projects.