汽水域における生物生産 : 中海水系における生産関係を中心にして

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From the investigation carried out in the water system connecting Lake Shinji-ko (weakly brackish), LakeNaka-umi (strongly brackish) and Miho bay (oceanic), thefollowing results were obtained. The distribution of planktonic organisms and benthonic animals was restricted to each of the three water bodies, and seasonal change of their biomass was most remarkable in Lake Naka-umi. The benthonic fauna of Lake Shinji-ko changed during the last three decades, from a fresh water fauna to brackish, and then to a fresh water one. Nektonic animals were not restricted to any one of the three water bodies. In Lake Shinji-ko and in Miho bay, the food items of each species of fish were limited in narrow range, but were very broad in Lake Naka-umi. That is, most fishes were monophagous in the former two areas throughout the year, but euryphagous throughout the year or changed their foods seasonally in Lake Naka-umi. 2) In general, brackish water is known to be one of the most productive of all habitat areas. Although it has not been pointed out specifically, that fishes living in brackish waters are more euryphagous than those of fresh water or marine water has been clearly recognized in previous works. The present investigations hows that the production efficiency of fish to food organisms was much higher in Lake Naka-umi than in the other two water bodies, probably partly due to that most fishes were euryphagous and there were virtually no useless organisms in Petersen's sense. 3) It was recently discovered, not only in estuarine waters but also in other aquatic and terrestrial habitats, that the distribution and biomass of organisms can be determined in some cases by the competitive or predatory organisms, and that the production rate of the organisms changed greatly under the presence of predatory animals. This appears to indicate that the interrelations between organisms should be taken into consideration to a greater extent in analysing the distribution of organisms. 4) The biotic community shoul dnot be recognized as an organismic unit or a simple assemblage of organisms of different species living in the samearea. It must be recognized in the context of the relations among organisms. The whole relation among species is, however, very difficult to detect if sought only through the investigation on the assemblage of organisms. So, paleo-synecological studies can not be based solely on the investigation on the assemblage of fossils, but also on an investigation on the relationship of recent organisms and its application to the fossil ones. 5) To understand fully the ecology of recent organisms, paleoecological information is needed for interpretation of the origins of their life modes and of the interrelations between species; on the other hand paleoecology may be in the needs of the knowledge from the community ecology on recent organisms to acquire its guiding principles.
日本地質学会の論文
1968-12-28

汽水域における生物生産 : 中海水系における生産関係を中心にして

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