A STUDY OF EFFECTS OF WATER ACIDIFICATION ON AQUATIC ORGANISMS OF DIFFERENT TROPHIC LEVELS
水质酸化对水生生物影响的研究

A study was carried to assess the effects of low pH (treatment under pH 3.0, 4.5, 5.0, 5.5, and 6.0) on aquatic organisms of different trophic levels. Results indicated that at pH 5.5-8.3 the fluctuation of the abundance of aquatic organisms was generally normal. At pH 5.0, abundance of zooplankton increased while abundance of algae and heterotrophic bacteria reduced because the later two categories were repressed by a large quantity of zooplankton. At pH 5.0, abundance of pulmonata, aquatic insects and duckweed reduced and growth rates of fish decreased. At pH 4.5, abundance of zooplankton descended rapidty while pulmonata and duckweed descended progressively. When a few predator presented, algae and heterotrophic bacteria increased and a large number of acid resistingl arvae of aquatic insects (Chirononus dorsalis) hatched. At pH 3.0, abundance of zooplankton, pulmonata, aquatic insect, duckweed and heterotrophic bacteria reduced to zero. The resisting threshold of aquatic organisms to low pH was within the range of pH 5.0-5.5.