maintained at a density of 1.0 Â 10
2 N/mL. With the addition of 200 mg/L of soap,
Cyclidium glaucoma disappeared from the system. It seems that the recovery of
Cyclidium glaucoma was due to the degradation of complexed soap by bacteria. The
density of Tolypothrix sp. slowly decreased to approximately 2.0 Â 10
1 cm/mL
11 days after the addition of soap concentrations of up to 50 mg/L. The slow
decrease in the density of Tolypothrix sp. was considered to have been driven by
the light inhibition of soap scum. The densities of Lecane sp. and Philodina
erythrophthalma slowly recovered in concentrations of up to 50 mg/L, ranging
from 6.0 Â 10
1 N/mL to 1.1 Â 10
2 N/mL. The reason for the slow recoveries of
Lecane sp. and Philodina erythrophthalma was assumed to be that they fed on
bacteria, which increased in density due to the organic nature of complexed soap.
With the addition of 200 mg/L of soap, the population of Aeolosoma hemprichi
slowly decreased and finally disappeared from the system. Only Chlorella sp. was
independent of the complexed soap at all concentrations. It follows from these
Fig. 7.4 Time course of P/R ratio in STS-, SHS-, and SOS-added microcosm N-system
7 Example Assessments of the Microcosm N-System
77