It is well known that the benthic biota in the river ecosystem changes drastically between the mountain and urban streams. However, there are few studies demonstrating the changes in biota by using quantitative techniques. In this study, field research on benthic species (mainly aquatic insects) was carried out at 6 different sites (St. 1-3: mountain sites, St. 4-6: urban sites) in the Kanna River which is the typical river in Japan. Sample collection was carried out every other month during February 2012 to January 2013 by a Beck-Tsuda method. In total, we identified 7879 benthos of 153 species. We compared the biota quantitatively by using an EPT (Ephemeroptera, Plecoptera, and Trichoptera) index and a pollution index (Pantle-Buck Method). The EPT index focuses on the species which have no pollution tolerance. On the other hand, the pollution index focuses on the species which have pollution tolerance. Calculated EPT index tended to decrease toward the lower reaches (0.81 at St. 1; 0.50 at St. 6). This indicates that the water quality in the urban stream is getting worse. The values of pollution index tended to increase toward the lower sites (1.0 at St. 1; 1.5 at St. 6). This tendency was consistent with that of the EPT index. The lower reaches of the Kanna River has a large population who has insufficient sewage treatment system. Consequently, the significant changes in benthic biota between mountain and urban sites are supposed to be caused by water contamination in the urban area.
Hideki Sato, Takasaki City University of Economics, Japan
Akihiro Iijima, Takasaki City University of Economics, Japan
Stream: Environmental Sustainability & Environmental Management: Freshwater, Oceans and Seas
This paper is part of the IICSEEHawaii2017 Conference Proceedings (View)
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