Река Параиба-ду-Сул: экологические проблемы и биоразнообразие юго-восточной Бразилии.

River in southeast Brazil
the municipality

The Paraíba do Sul (ˈʁiu pɐɾɐˈibɐ du ˈsuw), or simply termed Paraíba, is a river in southeast Brazil. It flows west to northeast from its farthest source at the source of the river Paraitinga to the sea near Campos dos Goytacazes. The river receives its name when it meets the river Paraibuna at the Paraibuna dam. Its main tributaries are the rivers Jaguari, Buquira, Paraibuna, Preto, Pomba and Muriaé. These last two are the longest and join the main river and from the mouth respectively
The valley of the Paraíba do Sul ranges from the latitudes 20°26' and 23°39'S and the longitudes of 41° and 46°30'W and covers an area of about distributed over three states. The main economic activities are industry and cattle raising.

Unlike rivers in northern Brazil where seasonal variations in water temperature generally are relatively limited, those 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 26.6 °C (80 °F) in the summer to 15.2 °C (59 °F) 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)

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. including 46 species of non native fish and the parasitic copepod Lernaea cyprinacea. Several native species (e. g., Brycon insignis, Pogonopoma parahybae) are seriously threatened, and a general fall in abundance and species richness has been observed. 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.