12.2 Summary and Further Perspectives
Although ecological risk assessment has been conducted on the risk posed by toxic
chemicals to an individual species, the microcosm method can assess the state of
recovery and change of an ecosystem by fragmentation, which is not shown in
single-species tests. Further, the microcosm test can be used to conduct assessments
equivalent to those of conventional mesocosms, measuring changes in the abundance of organisms. The scientific importance of being able to continuously measure
changes in the function of an ecosystem is great. This study suggests that even when
a microcosm experiences structural effects, the functional stability of the ecosystem
can be maintained due to the redundancies at the population or community level.
This shows that when a functional effect is emphasized in an ecosystem impact
assessment, proper assessment cannot be conducted by measuring structural parameters (species composition, abundance, etc.), which are generally measured, and that
it is necessary to measure functional parameters directly.
The microcosm test method was shown as effective for assessing the impacts of
biological interactions, which might be overlooked in single-species tests. In particular, there were protozoans and metazoans in the microcosm, which have not
conventionally been used, and it was indicated that the existence of these taxa was
important for evaluating the influence on the microbial ecosystem. Additionally, it
was clarified that the P/R ratio assessment method using the model ecosystem
hydrosphere (microcosm) could acquire the basic information needed to determine
the influence of various chemical substances on the ecosystem and that it was a
useful technique for protecting natural ecosystems using the appropriate management of chemical substances. As for this assessment, an experimental method and
data analysis techniques are made available in the manual. Moreover, this ecosystem
impact assessment technique has become frequently used in Japan, and it offers the
possibility for OECD standardization. It may be said that the significance of this
approach for international environmental policy is extremely high. Additionally, the
importance of the patterns and environment impact assessment was adopted in the
final report of a task group of the Association of National Irradiation Ecology, titled
“Ecosystem approach to environmental protection,” and this report may possibly
have a substantial influence on the International Commission on Radiological
Protection (ICRP) or the Organization for Economic Cooperation and Development
Nuclear Energy Agency (OECD/NEA). It is expected that the microcosm test
method will contribute to an environmental radioprotection policy in Japan through
the advice of these international organizations, and it is thought that the ripple effect
could be tremendous. Additionally, it is at an early stage of development by the lead
laboratory and the domestic ring test in Japan, and it is the establishment and
unification of the test method (protocol), inspection (ring test) of the plasticity
between facilities, construction of the database, and the clarification of the application range that promote its prospects as an OECD standardized test method with
future development of the microcosm test. At this stage, it is necessary to improve
the database, inspect correlative analyses with natural ecosystems (mesocosms), and
evaluate the relationship with known toxic data. Having passed through these tasks,
210
R. Inamori et al.
Although ecological risk assessment has been conducted on the risk posed by toxic
chemicals to an individual species, the microcosm method can assess the state of
recovery and change of an ecosystem by fragmentation, which is not shown in
single-species tests. Further, the microcosm test can be used to conduct assessments
equivalent to those of conventional mesocosms, measuring changes in the abundance of organisms. The scientific importance of being able to continuously measure
changes in the function of an ecosystem is great. This study suggests that even when
a microcosm experiences structural effects, the functional stability of the ecosystem
can be maintained due to the redundancies at the population or community level.
This shows that when a functional effect is emphasized in an ecosystem impact
assessment, proper assessment cannot be conducted by measuring structural parameters (species composition, abundance, etc.), which are generally measured, and that
it is necessary to measure functional parameters directly.
The microcosm test method was shown as effective for assessing the impacts of
biological interactions, which might be overlooked in single-species tests. In particular, there were protozoans and metazoans in the microcosm, which have not
conventionally been used, and it was indicated that the existence of these taxa was
important for evaluating the influence on the microbial ecosystem. Additionally, it
was clarified that the P/R ratio assessment method using the model ecosystem
hydrosphere (microcosm) could acquire the basic information needed to determine
the influence of various chemical substances on the ecosystem and that it was a
useful technique for protecting natural ecosystems using the appropriate management of chemical substances. As for this assessment, an experimental method and
data analysis techniques are made available in the manual. Moreover, this ecosystem
impact assessment technique has become frequently used in Japan, and it offers the
possibility for OECD standardization. It may be said that the significance of this
approach for international environmental policy is extremely high. Additionally, the
importance of the patterns and environment impact assessment was adopted in the
final report of a task group of the Association of National Irradiation Ecology, titled
“Ecosystem approach to environmental protection,” and this report may possibly
have a substantial influence on the International Commission on Radiological
Protection (ICRP) or the Organization for Economic Cooperation and Development
Nuclear Energy Agency (OECD/NEA). It is expected that the microcosm test
method will contribute to an environmental radioprotection policy in Japan through
the advice of these international organizations, and it is thought that the ripple effect
could be tremendous. Additionally, it is at an early stage of development by the lead
laboratory and the domestic ring test in Japan, and it is the establishment and
unification of the test method (protocol), inspection (ring test) of the plasticity
between facilities, construction of the database, and the clarification of the application range that promote its prospects as an OECD standardized test method with
future development of the microcosm test. At this stage, it is necessary to improve
the database, inspect correlative analyses with natural ecosystems (mesocosms), and
evaluate the relationship with known toxic data. Having passed through these tasks,
210
R. Inamori et al.