A new approach of Integrated Health Responses (IHR(s)) modeling for ecological risk/health assessments of an urban stream.

The objective of this study was to evaluate the ecological health of an urban stream using Integrated Health Responses (IHRs). Water chemistry analysis, habitat health, and ecotoxicity tests were conducted in the stream along with analyses of molecular/biochemical, physiological biomarkers, and population-level responses in indicator species. Chemical stresses, measured as nutrient levels, ionic content and organic matter concentrations were significantly greater (p<0.01) at the downstream than the reference site (RF). The habitat health was largely impacted in the downstream reaches and had a negative relation with the land-use pattern of % urban area. Comet assay, 7-ethoxyresorufin-O-deethylase (EROD), acetylcholinesterase (AChE), and vitellogenin (VTG) were evaluated for low-level biomarker responses on DNA/physiological conditions of target species. The multi-metric fish model (Mm-F) was used to test the community-level response in relation to chemical and physical habitat stresses. The impaired responses of separate biomarker and bioindicator at the downstream sites occurred at all organizations from molecular/biochemical level to community level. Using all biomarkers/bioindicators, the star-plot model of IHRs was developed and then the integrative health/risk assessments were conducted in the urban stream. The reduced values of IHRs occurred in the downstream sites and the impacts were attributed to effluents from wastewater treatment plants (WTPs) and industrial complex. Ecological health impairments, thus, were evident in the urban reach, and reflected the long-term community responses as well as short-term responses of molecular biomarkers. The degradation of the urban stream was mainly due to a combined effect of chemical pollution and physical habitat modifications.