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Ecology and Environmental Issues of Aquatic Invertebrates in High Mountain Rivers of Northern Chile

Abstract:

In the Atacama and Coquimbo Regions (from 25°17'to 32°16'South latitude), located south of the Atacama Desert in northern Chile there are rivers with permanent flow regimes, drained by snow melting in spring and rainfall in winter. The main watersheds are formed by the Huasco, Elqui and Limarí rivers. These watersheds are highly valuable for economic development, human consumption and biodiversity. The regional geology, processes of mineralization and the climate conditions in higher systems of this region have produced fragile and extreme ecosystems. In particular, the Huasco and Elqui River basins possess metallic mineral deposits that produce river headwaters with high concentrations of metals and low pH. But there have also, been several mining projects in the high and low parts of both basins. As a result, these rivers have been greatly impacted by mining and agriculture activities, resulting in deterioration of water quality and quantity. Considering the importance of lacustrine bodies in arid lands and the vulnerability of these systems to overuse by anthropogenic activities, this chapter summarizes the results of benthic invertebrate surveys of the Huasco and Elqui Rivers, to describe the ecological status and the quality of these arid ecosystems and to relate the geochemical characteristics of river headwaters with diversity and distribution patterns of the aquatic communities. The ecological state of rivers will be evaluated by diversity and functional diversity indices. We begin with a brief overview of the major climatic, geological and hydrological characteristics of the study area. Then we analyse and compare spatial patterns of aquatic invertebrates in the Huasco and Elqui Rivers, we analyse the application of functional and ecological diversity indices, and finally we discuss the relationships between ecological and functional indices and environmental variables.