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Title: 1966年長崎県下に発生した赤潮現象と赤潮プランクトンOlisthodiscusの生態観察
Other Titles: Discoloration phenomena caused by microalgae in Nagasaki Pref. in 1966 and ecology of causative organisms, Olisthodiscus
Authors: 飯塚, 昭二 / 入江, 春彦
Authors (alternative): Iizuka, Shoji / Irie, Haruhiko
Issue Date: Dec-1968
Publisher: 長崎大学水産学部
Citation: 長崎大学水産学部研究報告, v.26, pp.25-35; 1968
Abstract: The present paper deals with the discoloration phenomena of marine and fresh water caused by microalgae in the southern parts of Nagasaki Pref. and with the ecology of one of these microalgae, namely Olisthodiscus population. The major phe-nomena described were of Peridinium cunningtonii occurred in Moto-ike (pond) in Shi-mabara City, of Trichodesmium erythraeum produced in the open sea and accumulated in Tamanoura Bay, Goto Islands and of Olisthodiscus sp. frequently occurred in the innermost part of Nagasaki Bay. In respect to the latter species, the following ecolo-gy was clarified by field observations. Olisthodiscus sp. often flourished in the water strata having the optimam environment of water temperature 23-30℃, chlorinity 17.5-18.0‰ following rainfall and its extreme increase finally caused the vigorous discoloration. The concentration attained to 200 mg/m3 in July (probably 300 mg/m3 in September) in the chlorophyll a content and 11.6 cc/l in the tension of dissolved oxygen in the surrounding water (degree of satur-ation: 240%). The organisms did not live at the bottom where chlorinity was unfavorable but in the surface and middle strata less than 5 meters in depth. Because of mobility of the organisms within these strata, the population was concentrated at the surface in the daytime but decreased at night. / 1966年長崎県下に発生した赤潮現象と,赤潮プランクトンOlisthodiscus群集の野外観察に基づく生態を報告した.ここで報告した赤潮現象の主なものは,島原市元池に発生した淡水産Peridinium cunningtoniiによるもの,五島玉ノ浦湾に発生した海産外洋種Trichodesmium erythraeumによるもの,および長崎湾で多発したOlisthodiscus sp.によるもの等である.そのうち後者については,下記のことを明らかにした. Olisthodiscus群集は,水温23~30℃,塩素量17.5~18.0‰を至適生息環境条件として,降雨のあと多発して赤潮状態となる.赤潮時の最高濃度はクロロフイルa量で200mg/m3に達し(9月赤潮では300mg/m3に達したと推測した),その時生産した酸素は海水中の溶存量を11.6cc/l(飽和度240%)まで高めた.海底水は塩素量規制があって,群集の生息層は5mの中層以浅に限られたが,この層内で日中は群集量を増大し,夜間は減少する日周性があるようである.日中の増大は多分に表面集中現象と解釈される面があり,Olisthodiscusの個体は表層と中層の間を自由に行動できる能力を持つようである.長崎湾では赤潮状態は湾最奥部で最も激しく,特に突堤に囲まれた場所とか突堤のすそにあたる滞溜域での着色が顕著である.降雨との関係については二次的原因としては有効であるが直接原因ではないことが指摘された.
URI: http://hdl.handle.net/10069/31326
ISSN: 05471427
Type: Departmental Bulletin Paper
Text Version: publisher
Appears in Collections:第26号

Citable URI : http://hdl.handle.net/10069/31326

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