Global change drivers including eutrophication, hydrological disturbance, climate change, chemical pollution, overexploitation, invasive species, and land-use change are affecting the function and structure of freshwater ecosystems. South American freshwater ecosystems are especially threatened by the combination of rising human pressures on natural resources (i.e., water use, intensive agriculture, mining, deforestation, and afforestation) and the lack of adequate legislation and economic resources for environmental protection and restoration. We assess the state of freshwater ecosystems in Argentina, Brazil, Chile, Colombia, Ecuador, Uruguay, and Venezuela, focusing on broad categories of human-induced threats grouped into 5 categories: climate change, watershed stressors, hydrological alteration, channel modification, and biological stressors. For most countries, the most severe threats are related to land uses such as mining, agriculture, and urban expansion. Other threats relate to the abstraction or wasteful use of water and the intense regulation of flows, including the effects of large hydraulic infrastructure. There is also an increasing need to empower public organisations that focus on environmental protection, to update or develop an adequate regulatory and legal framework, to provide adequate funding for the implementation of environmental legislation, and not least to implement ecological rehabilitation. Implementation of these steps would reduce the threats to South American aquatic ecosystems and allow progress toward the sustainable development of this region in future decades.

Coastal wetlands are ecosystems that provide multiple benefits to human settlements; nonetheless, they are seriously threatened due to both a lack of planning instruments and human activities associated mainly with urban growth. An understanding of their functioning and status is crucial for their protection and conservation. Two wetlands with different degrees of urbanization, Rocuant-Andalién (highly urbanized) and Tubul-Raqui (with little urbanization), were analyzed using temperature, salinity, dissolved oxygen, pH, turbidity, granulometry, fecal coliform, and macroinvertebrate assemblage variables in summer and winter. In both wetlands marked seasonality in salinity, temperature and sediment texture classification, regulated by oceanic influence and changes in the freshwater budget, was observed. In the Rocuant-Andalién wetland, the increases in pH, dissolved oxygen, gravel percentage, and coliform concentration were statistically significant. Urbanization generated negative impacts on macroinvertebrate assemblage structure that inhabit the wetlands; greater richness and abundance (8.5 times greater) were recorded in the Tubul-Raqui wetland than in the more urbanized wetland. The multivariate statistical analysis reflects the alteration of these complex systems.

Se caracterizó la calidad del agua en un río del sur de Chile a través de un Índice Biótico, en un contexto espacio-temporal y además se analizó la composición y distribución de macroinvertebrados bentónicos y su correlación con 14 parámetros físico-químicos. La toma de muestras ocurrió durante un año en 5 estaciones de muestreo en la cuenca del río Boroa. Se registró un total de 77 taxa, los órdenes más representativos fueron Ephemeroptera (43,30%), Diptera (24,16%) y Plecoptera (18,03%). Las especies más abundantes fueron Meridialaris diguillina, Nousia maculata (Ephemeroptera) y Limnoperla jaffueli (Plecoptera). Acordando al IBF modificado (Índice Biótico de Familias) los resultados indicaron excelente, muy buena y buena calidad de agua, la última calidad fue registrada principalmente en invierno. Los parámetros fisicoquímicos así mismo indicaron calidad de agua excepcional. Estos resultados indican un bajo nivel de impacto antropogénico en la cuenca. Al aplicar el Índice Biótico de Hilsenhoff modificado basado en macroinvertebrados, la influencia de la estacionalidad sobre la calidad del agua fue evidente.The water quality in a Southern Chile river was characterized using the Biotic Index in a spatio-seasonal context, to analyze the composition and distribution of benthic macroinvertebrates and their correlation with 14 physico-chemical parameters. Sampling was done over a year at 5 sampling stations in the basin of the Boroa River. A total of 77 taxa were recorded, with the most represented orders being the Ephemeroptera (43.30%), Diptera (24.16%) and Plecoptera (18.03%). The most abundant species were Meridialaris diguillina, Nousia maculata (Ephemeroptera) and Limnoperla jaffueli (Plecoptera). According to the modified FBI (Family Biotic Index), the findings indicated excellent, very good and good water quality, the latter quality being registered principally in winter. Likewise, the physico-chemical parameters indicated exceptional water quality. These results suggested a low level of anthropogenic impact in the basin. Applying the modified Hilsenhoff Biotic Index based on macroinvertebrates, the influence of seasonality on water quality was evident