completely differ in the composition of their microorganisms, the predictability of
this finding should be verified. However, the microcosm N-system, in which there is
a greater diversity of constituent species, may have greater resistance to this stressor.
In the microcosm subsystem, which consisted of three species, a stable coexistence was provided as in the microcosm N-system, which was comprised of 11 species, and thus an impact assessment, such as that of various chemical substances,
could reasonably be performed. However, problems arise in the microcosm
subsystem when using a single species each of producers, consumers, and decomposers, such as the lack of complex interactions between species and competition or
high-level trophic dynamics, which are among the most basic and important elements constituting an ecosystem. Because the microcosm was a model of ecosystem
function and regulated to evaluate the DO (a functional parameter) for the endpoint
of the impact assessment and the P/R ratio for the complexity of the operation, it was
assumed that a more detailed environmental assessment was enabled in the microcosm subsystem by utilizing positioning for a complementary subsystem of the
microcosm N-system. In other words, the microcosm subsystem can be used, but
greater accuracy and detail are provided using the microcosm N-system, which
includes more diverse biota. From such a point of view, the superiority of the
microcosm N-system for risk evaluations is clear.
Literature Cited
Jorgensen SE. Modeling for fate and effectof toxic substances in the environment. In: Developments in environmental Modelling 6. Amsterdam: Elsevier; 1984. 342pp.
Landner L. Chemicals in the aquatic environment, advanced hazard assessment. London: Springer;
1989. 415pp.
Leffler JW. The use of self-selected, generic aquatic microcosms for pollution effects assessment.
In: White HH, editor. Concepts in marine pollution measurement. College Park: University of
Maryland; 1984. p.139–58.
Resetatits WJ Jr, Bernoado J. Experimental ecology, issues and perspectives. Oxford: Oxford
University Press; 1998. 470pp.
11 A Subsystem Microcosm Verification of the Microcosm N-System
201
this finding should be verified. However, the microcosm N-system, in which there is
a greater diversity of constituent species, may have greater resistance to this stressor.
In the microcosm subsystem, which consisted of three species, a stable coexistence was provided as in the microcosm N-system, which was comprised of 11 species, and thus an impact assessment, such as that of various chemical substances,
could reasonably be performed. However, problems arise in the microcosm
subsystem when using a single species each of producers, consumers, and decomposers, such as the lack of complex interactions between species and competition or
high-level trophic dynamics, which are among the most basic and important elements constituting an ecosystem. Because the microcosm was a model of ecosystem
function and regulated to evaluate the DO (a functional parameter) for the endpoint
of the impact assessment and the P/R ratio for the complexity of the operation, it was
assumed that a more detailed environmental assessment was enabled in the microcosm subsystem by utilizing positioning for a complementary subsystem of the
microcosm N-system. In other words, the microcosm subsystem can be used, but
greater accuracy and detail are provided using the microcosm N-system, which
includes more diverse biota. From such a point of view, the superiority of the
microcosm N-system for risk evaluations is clear.
Literature Cited
Jorgensen SE. Modeling for fate and effectof toxic substances in the environment. In: Developments in environmental Modelling 6. Amsterdam: Elsevier; 1984. 342pp.
Landner L. Chemicals in the aquatic environment, advanced hazard assessment. London: Springer;
1989. 415pp.
Leffler JW. The use of self-selected, generic aquatic microcosms for pollution effects assessment.
In: White HH, editor. Concepts in marine pollution measurement. College Park: University of
Maryland; 1984. p.139–58.
Resetatits WJ Jr, Bernoado J. Experimental ecology, issues and perspectives. Oxford: Oxford
University Press; 1998. 470pp.
11 A Subsystem Microcosm Verification of the Microcosm N-System
201