Integrated Ecological River Health Assessments, Based on Water Chemistry, Physical Habitat Quality and Biological Integrity

Abstract

This study evaluated integrative river ecosystem health using stressor-based models of physical habitat health, chemical water health, and biological health of fish and identified multiple-stressor indicators influencing the ecosystem health. Integrated health responses (IHRs), based on star-plot approach, were calculated from qualitative habitat evaluation index (QHEI), nutrient pollution index (NPI), and index of biological integrity (IBI) in four different longitudinal regions (Groups I-IV). For the calculations of IHRs values, multi-metric QHEI, NPI, and IBI models were developed and their criteria for the diagnosis of the health were determined. The longitudinal patterns of the river were analyzed by a self-organizing map (SOM) model and the key major stressors in the river were identified by principal component analysis (PCA). Our model scores of integrated health responses (IHRs) suggested that mid-stream and downstream regions were impaired, and the key stressors were closely associated with nutrient enrichment (N and P) and organic matter pollutions from domestic wastewater disposal plants and urban sewage. This modeling approach of IHRs may be used as an effective tool for evaluations of integrative ecological river health.

Stream Health Evaluation Using a Combined Approach of Multi-Metric Chemical Pollution and Biological Integrity Models

“…Zacco platypus is a tolerant species and the most dominant fish species (27.35%), showing a spatial abundance followed by Zacco koreanus (11.62%), which is a sensitive species and displayed a spatial decline. The results are line with the previous studies [7].…”

“…Sestonic CHL-a annual mean values started dropping during 2008-2010 which were higher during the dry years, and then showed approximation in the wet years. This type of variation in the inter-annual means of nutrient contributing factors and sestonic CHL-a reflected the intensive agricultural activities downstream, as well as urban land-use [7,38,63]. …”

“…Therefore, it could be argued that the primary nutrient which was subsidizing the bulk share in the primary productivity (sestonic CHL-a) was phosphorus and originated from the agricultural paddocks in the area, while the nitrogen might be ample to fuel sustainable algal growth. Hitherto conducted numerous studies on streams [7,[64][65][66] suggested that other primary factors instrumental as limiting factors in the stream ecosystem were turbidity and short water residence time leading to light limitation. Similar results were pointed out in the Yeongsan River (South Korea) by Song et al [67].…”

“…nutrient regime (TN, TP and TN:TP), organic matter (BOD), ionic contents and solids (TSS and EC), and primary production indicator (CHL-a). Major nutrient contributing factors (i.e., TN, TP and TN:TP mass ratios) were key determinants of the water quality and eutrophication [7,69,70].…”

“…However, ecological health evaluation in streams and rivers is not so simple, rather it depends on a variety of combined factors. Such factors include water chemistry [6], physical habitat condition in terms of structural components [7], climatic…”