and Cyclidium glaucoma multiplied in the 1-times quantity addition system just after
addition, compared to N 30 , but Cyclidium glaucoma perished in the 10-times
quantity addition system, and Aeolosoma hemprichi, Philodina erythrophthalma,
and Lecane sp. remarkably increased from 4 times to 12 times in abundance. It is
thought that the factor leading to the population increase in Aeolosoma hemprichi,
Philodina erythrophthalma, and Lecane sp. was that it became easier to prey on
microorganisms when Cyclidium glaucoma perished. Furthermore, it is thought that
three kinds of predators multiplied in form to fill the niche of Cyclidium glaucoma in
the microcosm as a result of the 10-times quantity added of Tolypothrix sp. because
they have the characteristic of easily becoming an algal floc since Tolypothrix sp. is a
conferva, and Aeolosoma hemprichi and Philodina erythrophthalma multiply in a
cohesion body as a living space. In addition, it was thought that the extinction of
Cyclidium glaucoma was caused by the fact that an algal floc of Tolypothrix
sp. inhibited swimming. From the comparison of B 16–30 , because the abundance of
the predators, except Cyclidium glaucoma, increased with an increase in the quantity
of addition, it was revealed that the addition of Tolypothrix sp. had an influence on
the predator.
As a functional parameter, from the time course of DO and P/R ratio, it appears
that the amplitude (activity) increases with an increase in the quantity of addition.
Tolypothrix sp., a blue-green algae, photosynthesizes in the microcosm, but, when
comparing the 10-times quantity addition system with the 1-times quantity addition
system, the amplitude (activity) of the 10-times quantity addition was approximately
two times that of the 1-times quantity addition, and it was shown that the addition
quantity and activity did not necessarily agree. In addition, it is thought that the
transition of the system occurred regardless of an active increase, although
Cyclidium glaucoma perished in the 10-times quantity addition system, as for the
P/R ratio because it is stable in P/R ¼ 1.
7.14.9 Bacillus cereus MC (Decomposer)
The competitive relationship among the four species of bacteria that are the lowest
species in the microcosmic food chain was studied. Bacillus cereus MC, one of the
indigenous bacteria in the microcosm, was added at 1, 10, and 100 times the
abundance of indigenous bacteria in the microcosm, and its influence on the structure and function of the ecosystem was examined. Bacillus cereus MC slowly
decreased at 1-, 10-, or 100-times inoculation concentrations in viable counts
using the selective media method after microcosm inoculation, and the abundance
of microorganisms (in particular, its primary consumer, the protozoan ciliate
Cyclidium glaucoma) in the microcosm slowly increased. Bacillus cereus MC has
been shown to be a suitable food source for microcosm heterotrophs. By comparison, in N 30 , no significant difference was observed between the system with Bacillus
cereus added and the system without it (control system).
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K. Murakami et al.
addition, compared to N 30 , but Cyclidium glaucoma perished in the 10-times
quantity addition system, and Aeolosoma hemprichi, Philodina erythrophthalma,
and Lecane sp. remarkably increased from 4 times to 12 times in abundance. It is
thought that the factor leading to the population increase in Aeolosoma hemprichi,
Philodina erythrophthalma, and Lecane sp. was that it became easier to prey on
microorganisms when Cyclidium glaucoma perished. Furthermore, it is thought that
three kinds of predators multiplied in form to fill the niche of Cyclidium glaucoma in
the microcosm as a result of the 10-times quantity added of Tolypothrix sp. because
they have the characteristic of easily becoming an algal floc since Tolypothrix sp. is a
conferva, and Aeolosoma hemprichi and Philodina erythrophthalma multiply in a
cohesion body as a living space. In addition, it was thought that the extinction of
Cyclidium glaucoma was caused by the fact that an algal floc of Tolypothrix
sp. inhibited swimming. From the comparison of B 16–30 , because the abundance of
the predators, except Cyclidium glaucoma, increased with an increase in the quantity
of addition, it was revealed that the addition of Tolypothrix sp. had an influence on
the predator.
As a functional parameter, from the time course of DO and P/R ratio, it appears
that the amplitude (activity) increases with an increase in the quantity of addition.
Tolypothrix sp., a blue-green algae, photosynthesizes in the microcosm, but, when
comparing the 10-times quantity addition system with the 1-times quantity addition
system, the amplitude (activity) of the 10-times quantity addition was approximately
two times that of the 1-times quantity addition, and it was shown that the addition
quantity and activity did not necessarily agree. In addition, it is thought that the
transition of the system occurred regardless of an active increase, although
Cyclidium glaucoma perished in the 10-times quantity addition system, as for the
P/R ratio because it is stable in P/R ¼ 1.
7.14.9 Bacillus cereus MC (Decomposer)
The competitive relationship among the four species of bacteria that are the lowest
species in the microcosmic food chain was studied. Bacillus cereus MC, one of the
indigenous bacteria in the microcosm, was added at 1, 10, and 100 times the
abundance of indigenous bacteria in the microcosm, and its influence on the structure and function of the ecosystem was examined. Bacillus cereus MC slowly
decreased at 1-, 10-, or 100-times inoculation concentrations in viable counts
using the selective media method after microcosm inoculation, and the abundance
of microorganisms (in particular, its primary consumer, the protozoan ciliate
Cyclidium glaucoma) in the microcosm slowly increased. Bacillus cereus MC has
been shown to be a suitable food source for microcosm heterotrophs. By comparison, in N 30 , no significant difference was observed between the system with Bacillus
cereus added and the system without it (control system).
152
K. Murakami et al.