The application of chemical and biological multi-metric models to a small urban stream for ecological health assessments

Abstract Nutrient or/and organic pollutions have been used as one of the key factors influencing the stream health, so research approaches were frequently focused on chemical analysis rather and biological analysis. Our objective of the present study was to diagnose the chemical and biological stream health using chemical multi-metric model of nutrient pollution index (NPI) and biological multi-metric fish model of the index of biotic integrity (IBI), respectively in an urban stream. Seven years dataset from 2008 to 2014 were used for the health assessments. The nutrients regime (TN, TP), sestonic chlorophyll, total suspended solids (TSS), electrical conductivity, BOD, and COD showed a typical polluted stream with large temporal and spatial fluctuations due to variations of Asian monsoon rain. The analysis of fish trophic guilds and fish tolerance guilds showed that omnivore fish species and tolerant species were dominated the community and the proportions were directly determined by water chemistry (nutrient and organic matters). Chemical model of NPI showed “poor-very poor health condition” by the criteria of the model and showed same results with the biological model of fish IBI. The degradation of the stream health was mainly due to massive effluents from the wastewater treatment plants. Overall, our data suggest that the multi-metric chemical and biological models may be used as a key tool diagnosing the stream health condition in an urban stream.