The use of an aquatic microcosm for pollution effects assessment Original Research Article

The effects of Cu2+ ions and β-HCH (β-1,2,3,4,5,6-hexachlorocyclohexane) on microcosms containing bacteria, a protozoa (Cyclidium), two rotifers (Philodina and Lepadella) and a green alga (Chlorella) were investigated. The time-dependent changes in the respiration rate (community metabolic rate) were different from those of the control at a Cu2+ ion concentration of 0.4 ppm and at a β-HCH concentration of 0.1 ppm. The calculation of the time-dependent changes in the respiration rate was assumed to be used as an index which determines whether the concentrations of the chemical agents have an effect on the material cycles in the system. This inference was supported by the results calculated using the mathematical model of changing the maximum (physiological) growth rate coefficient of organisms. In addition, the possibility of changes in the degree of changes in the respiration rate when changing the growth rate coefficient was discussed based on the kinds of constituent organisms and the structure of the system.