Abstract
Surveys were conducted to clarify the long-term changes of environmental conditions and aquatic organisms in 1996 and 2008 in an urban stream. Water quality in 1996 had recovered compared to past conditions, with BOD concentration about 5 mg/l. By 2008, water quality had recovered further, with BOD not more than 2 mg/l. The number of fish species had increased from 2–13 in 1996 to 7–14 by 2008. Macroinvertebrate species had increased more than 2.5-fold: more than 40 species were identified. Periphytic diatom species also more than doubled: 52–58 species were identified. Results show the relationship between the recovery of water quality and numerical changes in the assemblages of fish, macroinvertebrates and periphytic diatoms. Additionally, results suggest that stream morphology, bed materials, and crossing structures affected the changes in fish. Changes in macroinvertebrates occurred according to bed materials and water temperature.
