impact on generic freshwater ecosystems. Additional examples include the “OPPTS
850.1925 Site-specific aquatic microcosm test, laboratory,” in which testing is
performed by reproducing a specific aquatic ecosystem, and the “OPPTS 835.3180
Sediment/water microcosm biodegradation test,” which measures biodegradation in
the bottom sediments at a given study site. However, the problem with these
approaches is that they lack standardized methods for creating a model ecosystem.
Furthermore, the reason model ecosystem testing is less frequently used in the
process of evaluating high risks, despite its utility, is that model ecosystem testing
is generally costlier than single-species testing (U.S. Environmental Protection
Agency 1980, 1981, 1982).
It is important to note that microbial ecosystems, consisting primarily of producers (algae), low-level consumers (microanimals), and decomposers (bacteria),
constitute the foundation of aquatic ecosystems. High-level predators such as fish,
together with the microbial ecosystem, play an especially important role in water
purification and material cycling in aquatic ecosystems. The microbial ecosystem is
composed of algae (as photosynthetic primary producers), microscopic animals
(acting as consumers), and heterotrophic bacteria (acting as decomposers). It is
important to consider the variation in parameters of the ecosystem due to contamination from chemical substances, such as nitrogen, phosphorus, pesticides, and
heavy metals. The microcosm method described in this manual is a test that utilizes
a flask-scaled model ecosystem that is sampled to form a microcosm, which is
equipped with the requirements necessary to solve the aforementioned challenges.
An important characteristic of this test is that by designating production (P) and
respiration (R) as endpoints in the aquatic microbial ecosystem, which can be easily
measured, analyzed, and assessed using a dissolved oxygen (DO) meter, it allows
researchers to resolve the issues of complexity and high costs associated with
traditional model ecosystem testing.
In assessing and analyzing an ecosystem, it is effective to utilize a complementary
dynamic analysis of a microbial community that uses a microcosm (i.e., a stable
model ecosystem), which has been established based upon aquatic monitoring data
and constitutes the core of the microcosm testing. Currently, traditional methods that
utilize a single species do not include the performance of ecosystem risk assessments
that examine the effects of chemical substances on ecosystem functions. In the
single-species techniques that have been used, ecosystem risk evaluations that
include the influence of chemical substances on ecosystem functioning have not
conventionally been performed. Furthermore, current ecological studies that utilize a
microcosm also emphasize the need for official methods (i.e., international standardization) to assess environmental impacts, which can thus be generalized and
used to ameliorate the complexity and high costs of assessment methods involved in
model ecosystem testing. The Organisation for Economic Co-operation and Development (OECD) test guidelines also discuss the importance of ecosystem assessments. From such a point of view, the development of an ecosystem-scale evaluation
of a microcosm model system can be deemed essential.
2
Y. Inamori and R. Inamori
850.1925 Site-specific aquatic microcosm test, laboratory,” in which testing is
performed by reproducing a specific aquatic ecosystem, and the “OPPTS 835.3180
Sediment/water microcosm biodegradation test,” which measures biodegradation in
the bottom sediments at a given study site. However, the problem with these
approaches is that they lack standardized methods for creating a model ecosystem.
Furthermore, the reason model ecosystem testing is less frequently used in the
process of evaluating high risks, despite its utility, is that model ecosystem testing
is generally costlier than single-species testing (U.S. Environmental Protection
Agency 1980, 1981, 1982).
It is important to note that microbial ecosystems, consisting primarily of producers (algae), low-level consumers (microanimals), and decomposers (bacteria),
constitute the foundation of aquatic ecosystems. High-level predators such as fish,
together with the microbial ecosystem, play an especially important role in water
purification and material cycling in aquatic ecosystems. The microbial ecosystem is
composed of algae (as photosynthetic primary producers), microscopic animals
(acting as consumers), and heterotrophic bacteria (acting as decomposers). It is
important to consider the variation in parameters of the ecosystem due to contamination from chemical substances, such as nitrogen, phosphorus, pesticides, and
heavy metals. The microcosm method described in this manual is a test that utilizes
a flask-scaled model ecosystem that is sampled to form a microcosm, which is
equipped with the requirements necessary to solve the aforementioned challenges.
An important characteristic of this test is that by designating production (P) and
respiration (R) as endpoints in the aquatic microbial ecosystem, which can be easily
measured, analyzed, and assessed using a dissolved oxygen (DO) meter, it allows
researchers to resolve the issues of complexity and high costs associated with
traditional model ecosystem testing.
In assessing and analyzing an ecosystem, it is effective to utilize a complementary
dynamic analysis of a microbial community that uses a microcosm (i.e., a stable
model ecosystem), which has been established based upon aquatic monitoring data
and constitutes the core of the microcosm testing. Currently, traditional methods that
utilize a single species do not include the performance of ecosystem risk assessments
that examine the effects of chemical substances on ecosystem functions. In the
single-species techniques that have been used, ecosystem risk evaluations that
include the influence of chemical substances on ecosystem functioning have not
conventionally been performed. Furthermore, current ecological studies that utilize a
microcosm also emphasize the need for official methods (i.e., international standardization) to assess environmental impacts, which can thus be generalized and
used to ameliorate the complexity and high costs of assessment methods involved in
model ecosystem testing. The Organisation for Economic Co-operation and Development (OECD) test guidelines also discuss the importance of ecosystem assessments. From such a point of view, the development of an ecosystem-scale evaluation
of a microcosm model system can be deemed essential.
2
Y. Inamori and R. Inamori