title: Ecological effects of various toxic agents on the aquatic microcosm in comparison with acute ionizing radiation.
abstract: The purpose of this study was an evaluation of the effect levels of various toxic agents compared with acute doses of ionizing radiation for the experimental model ecosystem, i.e., microcosm mimicking aquatic microbial communities. For this purpose, the authors used the microcosm consisting of populations of the flagellate alga Euglena gracilis as a producer, the ciliate protozoan Tetrahymena thermophila as a consumer and the bacterium Escherichia coli as a decomposer. Effects of aluminum and copper on the microcosm were investigated in this study, while effects of gamma-rays, ultraviolet radiation, acidification, manganese, nickel and gadolinium were reported in previous studies. The microcosm could detect not only the direct effects of these agents but also the community-level effects due to the interspecies interactions or the interactions between organisms and toxic agents. The authors evaluated doses or concentrations of each toxic agent which had the following effects on the microcosm: (1) no effects; (2) recognizable effects, i.e., decrease or increase in the cell densities of at least one species; (3) severe effects, i.e., extinction of one or two species; and (4) destructive effects, i.e., extinction of all species. The resulting effects data will contribute to an ecological risk assessment of the toxic agents compared with acute doses of ionizing radiation.
authors.affiliation: Environmental and Toxicological Sciences Research Group, National Institute of Radiological Sciences, 9-1 Anagawa-4-chome, Inage-ku, Chiba-shi, 263-8555, Japan. fuma@nirs.go.jp
authors.forename: S
authors.initials: S
authors.lastname: Fuma
authors.forename: N
authors.initials: N
authors.lastname: Ishii
authors.forename: H
authors.initials: H
authors.lastname: Takeda
authors.forename: K
authors.initials: K
authors.lastname: Miyamoto
authors.forename: K
authors.initials: K
authors.lastname: Yanagisawa
authors.forename: Y
authors.initials: Y
authors.lastname: Ichimasa
authors.forename: M
authors.initials: M
authors.lastname: Saito
authors.forename: Z
authors.initials: Z
authors.lastname: Kawabata
authors.forename: G G
authors.initials: GG
authors.lastname: Polikarpov
mesh_terms: D000818:Animals; D017753:Ecosystem; D004926:Escherichia coli; D005055:Euglena; D020387:Food Chain; D006863:Hydrogen-Ion Concentration; D019216:Metals, Heavy / Q000009:adverse effects*; D011839:Radiation, Ionizing; D013768:Tetrahymena; D018675:Toxicity Tests; D014871:Water Microbiology; D014873:Water Pollutants / Q000009:adverse effects*; D014881:Water Supply
chemical_list: D019216:Metals, Heavy; D014873:Water Pollutants