Stream health assessment using chemical and biological multi-metric models and their relationships with fish trophic and tolerance indicators
2020
Mamun, Md | An, Kwang-Guk
Nonsan Stream is a tributary of the Geum River that is strongly affected by urbanization and agricultural activities in the watershed. The present study was performed to diagnose the chemical and biological health of the stream from 2010 to 2016 using the multi-metric water pollution index (WPI) and index of biotic integrity (IBI) models. Monthly and annual variations in stream water chemistry were directly influenced by the monsoon season. Inputs of total phosphorus, suspended solids, and ionic substances, as well as dilution of total nitrogen, occurred during July and August. Chlorophyll increase was largely influenced by total phosphorus (R² = 0.43, p < 0.01), total nitrogen: total phosphorus ratio (R² = 0.54, p < 0.01), and electrical conductivity (R² = 0.81, p < 0.01). Principal component analysis showed that the abundances of omnivorous and tolerant species were higher than those of insectivorous and sensitive species due to nutrient and organic matter pollution in the stream. Fish composition analysis showed that Zacco platypus (pale chub, Cyprinidae) was the most dominant fish species in the stream, while sensitive fish species disappeared over time. Analysis of the Pearson correlation network revealed that water quality parameters were negatively correlated with trophic and tolerance indicators. Average multi-metric values of water pollution index from 2010 to 2016 ranged from 15 to 19 in the stream, indicating fair to poor chemical health. The modeled values of the multi-metric index based on biological integrity matched those of the chemical model. Moreover, the results of trophic and tolerance indicator analyses matched the chemical results. This outcome suggested that biological ecosystem health is directly influenced by chemical pollution.
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