Abstract
Abstract: Aim Freshwater communities respond to abiotic and biotic changes in the environment, and are widely used as indicators of environmental integrity. Fish have been one of the most used biological groups for this purpose. The Del Azul stream located in the pampean region of Argentina has been monitored using a physicochemical approach with this monitoring being sporadic due to economic and operational constraints associated with the chemical analyses. In this paper we developed an Index of Biotic Integrity for the Del Azul stream (IBIA) based on Karr´s Index of Biotic Integrity as an alternative. Methods We computed two existent physicochemical indexes for comparison, one of them is the NSF-WQI and the other one is a local index referred to as Water Quality Index for Del Azul Stream and based on the former. Results The three indexes followed similar trends along the examined reaches, showing good conditions in the upper basin, poor conditions just downstream of the urban area and a recovery state further downstream in the basin. Conclusions Since the IBIA followed the same patterns as the physicochemical indexes, has a lower implementation cost and it is simpler to apply, we promote it as an alternative to the traditional physicochemical water quality monitoring for pampean streams.
Highlights
Indexes are useful tools in water resources management because they integrate a complex array of values into a single value easier to interpret (Madalina & Gabriela, 2014)
Based on the hypothesis that the ichthyofauna responds to changes in environmental conditions and that due to this capability it could be used for stream biomonitoring, the objectives of our study were: (a) to develop an index of biotic integrity for the Del Azul stream based on the fish assemblage structure, (b) to compare its results among seven reaches along Del Azul stream with those from the traditional physicochemical water quality indexes
We already mentioned that biotic indexes could reflect past conditions, detect impairment associated with variables not accounted for in the physicochemical analyses or missed pulses of pollutants
Summary
Indexes are useful tools in water resources management because they integrate a complex array of values into a single value easier to interpret (Madalina & Gabriela, 2014). Physicochemical variables sometimes do not fully reflect the condition of a water body. They only show the conditions at the exact time of sampling which could not be coincident with sporadic pulses of pollutants. Even if a substance is detected, it could be hard to establish the risk it represents when found in trace amounts, especially if its potential biohazard is not fully understood (Karr, 1981; Karr & Chu, 2000; Springer, 2010; Holt & Miller, 2011; Abbasi & Abbasi, 2012). Using the biota for this purpose could provide evidence of the present conditions and of the past conditions or trends over time (Karr, 1981, 2006; Fausch et al, 1984; Karr et al, 1986; RodríguezOlarte & Taphorn, 1995; Mathuriau et al, 2011)
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