ENVIRONMENTAL EFFECTS OF URBANIZATION ON STREAMS AND RIVERS IN PATAGONIA (ARGENTINA): THE USE OF MACROINVERTEBRATES IN MONITORING

MISERENDINO MARIA LAURA; BRAND CECILIA

Advances in Environmental Research, Volume 6

Nova Science Publishers, Inc.

Lugar: NEW YORK; Año: 2009; p. 183 - 220

The Patagonia Ecoregion (> 1.000.000 km2) is located in the southern part of South America and is shared by Argentina and Chile. This remote region shows a remarkable environmental heterogeneity. In the Argentinean side the Mountains and the Plateau are the dominant landforms drained by several fluvial systems. Some watercourses are artificially regulated to provide electrical power, water supply and irrigation, while free-flowing watercourses sustain multiple activities as recreation, tourism, sport fishing and sailing. Despite their low population density (0.8-5 inhabitants/km2) and an economy mostly based on agriculture and cattle raising, there is strong evidence that the ecological integrity of river systems is being threatened. In this sense, flowing waters in urban basins in the cordillera have shown profound alterations in habitat conditions and biota. Moreover, urbanization has also resulted in ecological changes in rivers near the Atlantic coast, where the industrial development is higher. Main environmental changes detected in Patagonian urban rivers are alterations to their hydrological regimes, extensive channel and riparian modification (including regular dredging and clearing), and inputs of organic pollutants and sediments. Macroinvertebrate communities have been used in environmental monitoring in rivers and streams worldwide. Potential benefits of research on macroinvertebrates include the quick assessment of biological resources for conservation purposes and the detection of pollution through differences between predicted and actual faunal assemblages. Aquatic invertebrates in Patagonian environments have a high degree of endemism and remarkable biogeographic differences. Fortunately the recent improvement in our knowledge of the macroinvertebrate fauna allows us to use these organisms as indicators of environmental degradation, as in fact has happened in the recent few years.         In this chapter we examine some environmental problems in river basins of Neuquén, Río Negro and Chubut Provinces (Patagonia, Argentina) subjected to urban land use. We discuss the use of macroinvertebrates assessing urbanization impacts through different study cases. We postulate that an integral approach that combines direct biological assessment with physical, chemical and environmental analysis is highly advantageous to diagnose stream degradation. This combination is effective and straightforward to interpret and allow ?early warning? about negative environmental changes after disturbances. Macroinvertebrate community analyses are valuable for the detection of stream impairment in Patagonia and are recommended to monitor biological recovery, conservation and restoration efforts in the future.