Influence of ambient pH on freshwater invertebrates under experimental conditions

In experimental mesocosms differing in water pH, the communities of macroin vertebrates demonstrated marked differences in their species composition an d the quantitative ratios between the main groups of members (oligochaetes, chironomids, mollusks, etc.). The highest species diversity was recorded a t pH 4.09-8.65. It proved to decrease at pH below 4 and above 9. In experim ents on determining tolerance to water pH, seven groups of invertebrates di ffering in their adaptive potential were distinguished among 40 species fou nd en masse in the freshwater zoobenthos and zooperiphyton of the Upper Vol ga basin.