Effects of acute γ-irradiation on community structure of the aquatic microbial microcosm

• Published in: Journal of environmental radioactivity 2010-11, Vol.101 (11), p.915-922
• Main Authors: Fuma, Shoichi, Ishii, Nobuyoshi, Takeda, Hiroshi, Doi, Kazutaka, Kawaguchi, Isao, Shikano, Shuichi, Tanaka, Nobuyuki, Inamori, Yuhei
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Animals; Applied ecology; Biodiversity; Biological and medical sciences; Chlorophyta - genetics; Chlorophyta - radiation effects; Community; Cyanobacteria - genetics; Cyanobacteria - radiation effects; Denaturing Gradient Gel Electrophoresis; DNA, Ribosomal - chemistry; Ecotoxicology, biological effects of pollution; Fresh water environment; Fundamental and applied biological sciences. Psychology; Gamma Rays; Indirect effect; Interaction; Microcosm; Microorganism; Oligochaeta - genetics; Oligochaeta - radiation effects; Oligohymenophorea - genetics; Oligohymenophorea - radiation effects; Population Dynamics; Rotifera - genetics; Rotifera - radiation effects; Water Microbiology
• ISSN: 0265-931X; 1879-1700
• DOI: 10.1016/j.jenvrad.2010.06.007

To characterise indirect effects of ionising radiation on aquatic microbial communities, effects of acute γ-irradiation were investigated in a microcosm consisting of populations of green algae ( Chlorella sp. and Scenedesmus sp.) and a blue-green alga ( Tolypothrix sp.) as producer; a ciliate protozoan ( Cyclidium glaucoma), rotifers ( Lecane sp. and Philodina sp.) and an oligochaete ( Aeolosoma hemprichi) as consumer; and more than four species of bacteria as decomposers. Population changes in the constituent organisms were observed over 160 days after irradiation. Prokaryotic community structure was also examined by denaturing gradient gel electrophoresis (DGGE) of 16S rDNA. Principle response curve analysis revealed that the populations of the microcosm as a whole were not significantly affected at 100 Gy while they were adversely affected at 500–5000 Gy in a dose-dependent manner. However, some effects on each population, including each bacterial population detected by DGGE, did not depend on radiation doses, and some populations in the irradiated microcosm were larger than those of the control. These unexpected results are regarded as indirect effects through interspecies interactions, and possible mechanisms are proposed originating from population changes in other organisms co-existing in the microcosm. For example, some indirect effects on consumers and decomposers likely arose from interspecies competition within each trophic level. It is also likely that prey–predator relationships between producers and consumers caused some indirect effects on producers.