Integrated Water Quality Index for evaluation of environmental degradation.

HUED, A. C.; BISTONI, M. A.; WUNDERLIN, D.

Capital Federal, Bs. As., Argentina

Congreso; Reunión Anual de SETAC Latinoamérica; 2003

Society of Environmental Toxicology and Chemistry

Major changes in the water quality of aquatic resources often follow anthropogenic disturbances. Water quality can be determined using different approaches, including chemical, physical and biological variations. Changes of biotic communities can also detect variation in water quality. In USA and Europe it is frequently the use of fish as bioindicators of water quality. This situation is by far not common in Argentina, mainly because of the lack of enough data on the biology of native fishes as to use them as quality bioindicators. The central and lower sections of Suquía River Basin (Córdoba, Argentina) present densely populated urban settlements, which cause an increasing environmental impact due to the anthropogenic activities. Fishes are particularly affected and change their distribution and abundance as a consequence of the environmental deterioration. The main goal of this work was to assess the water quality of a section of Suquía River basin combining both biotic and abiotic parameters, thus giving an integrated view of the aquatic system. Simultaneous measurement of physical, chemical, and microbiological parameters as well as the collection of fishes from different stations on Suquía River was carried out from 1998 to 2002. The data from fish and chemical parameters were used to calculate an Integrated Water Quality Index (IWQI). Different statistical analyses were performed to determine sensitive and tolerant indicators of aquatic environmental. The best bioindicators of water quality were: the abundance of Astyanax eigenmanniorum, Rineloricaria catamarcensis, Gambusia affinis, Cnesterodon decenmaculatus, and the sensitive and tolerant species richness. Both biotic and abiotic variables were transformed following a water quality index protocol previously proposed by the research group. IWQI shows clear differences between stations with different water quality. The upper basin was characterized by the high IWQI values, which indicate quasi-pristine water conditions. Conversely, the areas located at or downstream of urban zones were characterized by severe environmental degradation. This work conforms the first approach to evaluate the deterioration of a basin in Argentina, based on integrated evaluation of both fish and physical-chemical parameters.