in southern Brazil, such as Paraíba do Sul, exhibit distinct differences between winter and summer. During a survey of the river in Lorena, São Paulo, the water varied from in the summer to in the winter. The pH is neutral and generally fluctuates between 6 and 8. The Paraíba do Sul basin is home to just above 100 native fish species with most in the families Loricariidae, Characidae and Trichomycteridae. About 40% of the fish species in the river basin are endemic (the genus Oligobrycon is entirely restricted to the basin) and new species have been discovered in recent years, including the small catfish Pareiorhina hyptiorhachis that only was scientifically described in 2013. As a consequence of flowing through one of the most densely populated and industrialised parts of Brazil, the Paraíba do Sul suffers from pollution. Studies of the native cichlid Geophagus brasiliensis have found that levels of some heavy metals exceed the limits set by the Brazilian Food Legislation. Other threats are dams and the approximately 70 introduced species, including 46 species of non-native fish and the parasitic copepod Lernaea cyprinacea. Several native species (e.g., Brycon insignis, Pogonopoma parahybae and Steindachneridion parahybae) are seriously threatened, and a general fall in abundance and species richness has been observed. Some, such as the endemic Hypostomus auroguttatus, have successfully adapted to the changes. The catfish Potamarius grandoculis is only known from the vicinity of the mouth of the Paraíba do Sul and Doce Rivers, but it may already be extinct. Other threatened species in the Paraíba do Sul basin are the bivalves Diplodon dunkerianus, D. expansus and D. fontaineanus, and the Hoge's side-necked turtle (Mesoclemmys hogei). A national conservation plan with recommendations for the river basin was published in 2010. References Rivers of Minas Gerais Rivers of Rio de Janeiro (state) Rivers of São Paulo (state)