and Cyclidium glaucoma and Lecane sp. increase in the 1-times quantity addition
system; Chlorella sp. was preyed on by Philodina erythrophthalma. It is thought that
a 1-times quantity addition of Philodina erythrophthalma is enough to control a
population of the chlorophyceans because there is no difference seen in the decrease
in Chlorella sp. between the 1-times quantity and 10-times quantity from these
additions and from the comparison with B 16–30 .
As a functional parameter, from the comparison of DO and the P/R ratio, because
the amplitude could be confirmed in both systems, production and respiration were
shown to function in accordance with the light and dark period in the system. In
addition, an activity increase was observed with a quantity of addition, same as in
other addition systems. The P/R ratio converged at P/R ¼ 1, and it followed that the
ecosystem function did not come to change with the 10-times quantity addition of
Philodina erythrophthalma.
7.14.4 Aeolosoma hemprichi (Top Predator
in the Microcosm N-System)
The microcosm was loaded with Aeolosoma hemprichi, which is the top predator in
this gnotobiotic microcosm. For on-site biomanipulation, the top predator and/or
primary predator were introduced into the eutrophied ecosystem to reduce irregular
phytoplankton growth, such as an algal bloom. As the structural parameter, the green
algae Chlorella sp. and Scenedesmus quadricauda largely decreased after the
addition of Aeolosoma hemprichi, in a 10-times load system. The decrease of
Chlorella sp. and Scenedesmus quadricauda depends on the predation of Aeolosoma
hemprichi. The 10-times load system was effective for large decreases of the
phytoplankton. Cyclidium glaucoma, the primary predator, was increased to about
five times, but Lecane sp. just decreased in the community with three kinds of
zooplankton as predators. Because the growth rate of the bacteria was the highest
compared to the other constituent microorganisms, Cyclidium glaucoma preyed on
the increased bacteria, and it was thought that Cyclidium glaucoma populations
increased. As the functional parameter, the amplitude of the 10-times loaded system
is larger than the 1-times loaded system. In a natural ecosystem, creatures with an
ecological position equivalent to that of Aeolosoma hemprichi and Cyclidium glaucoma could potentially be introduced in on-site biomanipulation. It was shown that
the introduced ecosystem recovers to a state similar to before the introduction by
keeping down microorganisms and the detritus when indigenous phytoplankton
decreased within a system.
When Aeolosoma hemprichi, the top predator, was introduced, the green algae
and cyanophyceans did not decrease in the 1-times loaded system under its predation. However, a population of the green algae was reduced to half just after the
addition in the 10-times load. Therefore, it was suggested that the introduction of the
top predator (top-down) had an influence on the ecosystem structure (Fig. 7.38).
7 Example Assessments of the Microcosm N-System
147
system; Chlorella sp. was preyed on by Philodina erythrophthalma. It is thought that
a 1-times quantity addition of Philodina erythrophthalma is enough to control a
population of the chlorophyceans because there is no difference seen in the decrease
in Chlorella sp. between the 1-times quantity and 10-times quantity from these
additions and from the comparison with B 16–30 .
As a functional parameter, from the comparison of DO and the P/R ratio, because
the amplitude could be confirmed in both systems, production and respiration were
shown to function in accordance with the light and dark period in the system. In
addition, an activity increase was observed with a quantity of addition, same as in
other addition systems. The P/R ratio converged at P/R ¼ 1, and it followed that the
ecosystem function did not come to change with the 10-times quantity addition of
Philodina erythrophthalma.
7.14.4 Aeolosoma hemprichi (Top Predator
in the Microcosm N-System)
The microcosm was loaded with Aeolosoma hemprichi, which is the top predator in
this gnotobiotic microcosm. For on-site biomanipulation, the top predator and/or
primary predator were introduced into the eutrophied ecosystem to reduce irregular
phytoplankton growth, such as an algal bloom. As the structural parameter, the green
algae Chlorella sp. and Scenedesmus quadricauda largely decreased after the
addition of Aeolosoma hemprichi, in a 10-times load system. The decrease of
Chlorella sp. and Scenedesmus quadricauda depends on the predation of Aeolosoma
hemprichi. The 10-times load system was effective for large decreases of the
phytoplankton. Cyclidium glaucoma, the primary predator, was increased to about
five times, but Lecane sp. just decreased in the community with three kinds of
zooplankton as predators. Because the growth rate of the bacteria was the highest
compared to the other constituent microorganisms, Cyclidium glaucoma preyed on
the increased bacteria, and it was thought that Cyclidium glaucoma populations
increased. As the functional parameter, the amplitude of the 10-times loaded system
is larger than the 1-times loaded system. In a natural ecosystem, creatures with an
ecological position equivalent to that of Aeolosoma hemprichi and Cyclidium glaucoma could potentially be introduced in on-site biomanipulation. It was shown that
the introduced ecosystem recovers to a state similar to before the introduction by
keeping down microorganisms and the detritus when indigenous phytoplankton
decreased within a system.
When Aeolosoma hemprichi, the top predator, was introduced, the green algae
and cyanophyceans did not decrease in the 1-times loaded system under its predation. However, a population of the green algae was reduced to half just after the
addition in the 10-times load. Therefore, it was suggested that the introduction of the
top predator (top-down) had an influence on the ecosystem structure (Fig. 7.38).
7 Example Assessments of the Microcosm N-System
147