Unlike tropical South American rivers, where the annual variations in temperature are relatively limited, the water in the subtropical Iguazu River varies significantly depending on season. At two sites, one located just above and another just below the falls, the water at both varied from about 15.5 to 29 °C (60–84 °F), and average was just below 22 °C (72 °F).[9] The pH is typically near-neutral, ranging from 5.9 to 8.7.[9]
The unusual Aegla crustacean are locally common in the Iguazu River Basin.[16]
Environmental issues
In July 2000 more than 4,000,000 litres (1,100,000 US gal) of crude oil spilled into the river from a state-run oil refinery in the municipality of Araucária near Curitiba.[17]
^ abcDaga, Debona, Abilhoa, Gubiani & Vitule (2016). Non-native fish invasion of Neotropical ecoregion with high endemism: a review of the Iguaçu River. Aquatic Invasions 11(2): 209-223.
^ abPiálek, Dragová, Casciotta, Almirón & Řičan (2015). Description of two new species of Crenicichla (Teleostei: Cichlidae) from the lower Iguazú River with a taxonomic reappraisal of C. iguassuensis, C. tesay and C. yaha. Historia Natural 5(2): 5-27.
^Ferrareze & Nogueira (2015). Impact assessment of the introduction of Cichla kelberi in a large Neotropical reservoir and its lateral lagoons (Upper Paraná River Basin, Brazil). Braz. J. Biol. 75(4).
^Gubiani, Frana, Maciel & Baumgartner (2010). Occurrence of the non-native fish Salminus brasiliensis (Cuvier, 1816), in a global biodiversity ecoregion, Iguaçu River, Paraná River basin, Brazil. Aquatic Invasions 5 (2): 223-227.
^Cyrino, Bureau & Kapoor, editors (2008). Feeding and Digestive Functions of Fishes. p. 45. Science Publishers. ISBN978-1-4398-4269-0