陸水学雑誌第62巻2号abstract
原著
茶抽出液によるアオコ増殖抑制への効果
笹尾 敦子・松尾 宏・田中 義人
摘要
茶(Camellia sinensis (L.) O. Kuntze var. sinensis)の水抽出液により，アオコ発生の制御の試験を試みた。
茶の水抽出液(風乾した茶葉1gに100mLの水を加え，120℃，15分間オートクレーブした液。この溶液の濃度は10gL-1で表す)でアオコの原因藻類の1つであるMicrocystis aeruginosaの増殖阻害試験を行った。
その結果，5 day-EC50が7.7 mg L-1で，茶の抽出液が，M. aeruginosaの増殖阻害に有効であることが明らかになった。
また，同様に緑藻類のSelenastrum capricornutumに対しても3 day-EC50は10.8 mg L-1でM. aeruginosaと近い値を得た。
このEC50の濃度ではミジンコ及びヌカエビの生育阻害は起こらないので(48 hr-LC50，4 day- LC50はいずれも約430 mg L-1)，茶抽出液による藻類増殖阻害濃度は自然界の動物に対する影響は少ないと考えられた。
キーワード：茶，アオコ，増殖阻害，タンニン酸
[ Original article ]
Inhibitory effect of tea (Camellia sinensis (L.) O.Kuntze var.sinensis ) Liquor / extract on blue-green algal growth
Atsuko SASAO, Hiroshi MATSUO and Yoshito TANAKA
Fukuoka Institute of Health and Environmental Sciences,
39 Mukaizano, Dazaifu, Fukuoka 818-0135, Japan.
Abstract
The control of blue-green algal (Microcystis aeruginosa) growth was studied using tea, which has been long the most popular beverage among Japanese and is also prized as a medical herb.
After a 5-day culture of M. aeruginosa in M11 culture medium with tea liquor / extract (autoclaved tea leaves with a 1 g dry weight in 100 mL water and a concentration of 10 gL-1) , it appeared that the tea liquor / extract was useful as a growth inhibitor of M. aeruginosa.
The 5-day-EC50 value was 7.7 mg L-1.
The inhibition to green alga (Selenastrum capricornutum, 3 days) showed nearly the same EC50 value as M. aeruginosa, whereas LC50 value for Daphnia magna (48 hrs) and Paratya compressa improvisa (4 days) used to test the sensitivity of organisms to water toxicity were around 430 mg L-1.
We concluded that the toxicity of tea liquor / extract for D. magna and P.compressa improvisa was low.
Key words: tea, M. aeruginosa, growth inhibitor, trannic acid
E-mail (A.Sasao): sasao@star.fishes.pref.fukuoka.jp
[ Preface ]
Significance of recent researches into the organic community in Lake Suwa
Takayuki HANAZATO
Research and Education Center for Inlandwater Environment,
Shinshu University, 5-2-4 Kogandori, Suwa 392-0027, Japan
Abstract
Studies of the organic community in Lake Suwa have been performed since 1907. During the long history of such studies, lake eutrophication reached serius levels in 1960s and 1970s, and eutrophication problems occurred.
These studies have, therefore, reflected the changes in the community associated with lake eutrophication.
In order to solve the resultant problems, a sewrage system was built in the lake catchement area in 1979, and the residential area covered by the system has increased since that time.
Nevertheless, the lake water quality had not been markedly restored for about the last 20 years.
Around 1997, however, the seasonal patterns in various parameters of the organic community started to change.
This may indicate that ecosystem of Lake Suwa is changing associated with changes in lake water quality, which is being markedly restored.
Therefore, since current studies are starting to show how the ecosystem responds to the water quality improvement, such studies should be intensified.
To effectively conduct such studies in future, it is very important to review the results of recent studies on the organiccommunity of the lake.
For this purpose, five review papers were produced and are presented in this special issue.
They concern chironomid populations, zooplankton, bloom-forming cyanobacteria and its toxins, and the fish community;
all of which are characteristic of the Lake Suwa ecosystem.
Three of them (papers on chironomids and zooplankton ) are published in the present issue, while the remaining two will appear in the next issue.Key words: Lake Suwa, organic community, eutrophication
E-mail (T.Hanazato) : hanazato@po5.lcv.ne.jp
特集：諏訪湖の生物群集の研究
総説
諏訪湖におけるユスリカ研究(1)幼虫に関する知見を中心に
中里 亮治・平林 公男・沖野外輝夫
摘要
諏訪湖におけるユスリカに関する研究について、幼虫に関する知見を中心にこれまでの報告を整理した。
宮地（1928）による報告以後，多くの研究者によって諏訪湖のユスリカについての種組成，季節消長，幼虫の分布，幼虫の浮泳活動，魚の餌としてのユスリカおよび物質代謝におけるユスリカの役割に関する研究がなされてきた。
これらの報告をもとにして，ユスリカ幼虫密度の変化と富栄養化の関係について考察を加えた。
さらに，近年の諏訪湖のユスリカの生態および今後の研究課題について言及した。
キーワード：諏訪湖，ユスリカ，幼虫，個体群動態，水平分布，富栄養化
Special issue: Studies on the organic community in Lake Suwa
[ Review ]
Studies on chironomids in Lake Suwa (1) Larvae
Ryoji NAKAZATO1), Kimio HIRABAYASHI2) and Tokil OKINO3)
1)Center for Water Environment Studies, Ibaraki University,
Ohu 1375, Itako, Ibaraki 311-2402, Japan
2)Department of Applied Biology, Faculty of Textile Science and Technology,
Shinshu University, 3-15-1 Tokida, Ueda, Nagano 386-8567, Japan
3)Department of Environmental Sciences, Faculty of Science,
Shinshu University, Asahi 3-1-1, Matsumoto, Nagano 390-8621, Japan
Abstract
The studies on the chironomids in Lake Suwa are reviewed with special reference to the informa-tion on larvae.
Since 1928, many investigators have studied chironomid fauna as well as their population dynamics, larval distribution on the lake bottom, swimming behaviour, predation by fish, thir roles in the material cycles, etc.
The changes in population densities of Prosilocerus akamusi and Chironomus plumosus larvae in relation to the eutrophication of Lake Suwa are discussed.
Furthermore, recent characteristics of chironomid ecology in Lake Suwa are examined and future subjects matters are suggested.Key words: Lake Suwa, chironomids, larvae, population dynamics, horizontal distribution, eutrophication
E-mail (R.Nakazato) : nakazato@mito.ipc.ibaraki.ac.jp
特集：諏訪湖の生物群集の研究
総説
諏訪湖におけるユスリカ研究(2)不快昆虫としての成虫とその防除対策に関する検討
平林 公男・中里 亮治・沖野外輝夫
摘要
諏訪湖周辺域では，毎年大量のユスリカ成虫が湖沿岸域に定期的に飛来し，住民の日常や観光業へ大きな支障をきたし，社会問題をなっている。
本研究では，諏訪湖におけるユスリカ類の成虫に焦点をあて，これまでの研究報告を整理し，(1)主な発生種の特徴，(2)近年の大量発生・大量飛来のメカニズム，(3)人々の生活とユスリカ成虫との関わりなどについて紹介した。
また，成虫対策のために行われてきた野外実験として，(1)成虫の飛翔行動の特徴や休息習性などを利用した対策研究，(2)光や音による成虫誘引に関する実験などの概要を紹介し，ユスリカ類との共存を視野に入れた総合防除対策について述べた。キーワード：ユスリカ類，防除対策，飛翔行動，諏訪湖，不快昆虫
Special issue: Studies on the organic community in Lake Suwa
[ Review ]
Studies on chironomids in Lake Suwa
(2) adult midges as nuisance insects and plans for their control
Kimio HIRABAYASHI1), Ryoji NAKAZATO2) and OKINO3)
1)Department of Applied Biology, Faculty of Textile Science and Technology,
Shinshu University, 3-15-1 Tokida, Ueda, Nagano 386-8567, Japan
2)Center for Water Environment Studies, Ibaraki University,
Ohu 1375, Itako, Ibaraki 311-2402, Japan
3)Department of Environmental Sciences, Faculty of Science,
Shinshu University, Asahi 3-1-1, Matsumoto, Nagano 390-8621, Japan
Abstract
In the area surrounding Lake Suwa, massive flights of adult midges have been recurring causing problems in the daily life of local residents.
In this paper, we gave an outline of adult midges of chironomidae in recent years, including:
(1) characteristics of main chironomid species;
(2) factors encouraging massive flights of midges from the lake to human habitats;
and (3) the relationship between human activities and adult midges.
Moreover, we examined the countermeasures for their control:
(1) studies on flight behaviour and resting habit of adult midges;
and (2) the field trial trapping control method of adult midges by attracting them to lights and sounds in Lake Suwa.
Any plants which effectively promote the ideal of human coexistence with other organisms as auxiliary measures must be examined.Key words: chironomid midge, control, flight behavior, Lake Suwa, nuisance
E-mail (K.Hirabayashi) : kimio@giptc.shinshu-u.ac.jp
特集：諏訪湖の生物群集の研究
総説
諏訪湖の動物プランクトン群集：群集構造と生態系における役割
花里孝幸・荒河 尚・佐久間昌孝・張 光玹・沖野外輝夫
摘要
これまでなされた研究結果を基に，諏訪湖の動物プランクトンの群集構造と生態系における役割についてまとめた。
諏訪湖の動物プランクトン群集では，春にはワムシ類が優占し，夏から秋にかけては優占種が小型枝角類に変わった。
優占種とそれらの季節変化は1960年代から1990年代に至るまで大きな変化はなかったようにみられる。諏訪湖では２種のBosmina，B.longirostrisとB.fatalisの遷移に季節的に明瞭な交互性が見られる。
すなわち，B.longirostrisが春と秋に優占し，B.fatalisが夏に優占する。B.fatalisの夏の優占度と夏の平均水温やクロロフィル量との間に正の相関が見られたことから，その優占にはアオコの発生が何らかの関わりを持っていることが示唆された。
湖沼生態系のしくみを理解するため，大型の隔離水界を諏訪湖に設置して実験的に解析が行われた。
それにより，諏訪湖における動物プランクトンに係わる食うー食われる関係や競争関係などの生物間相互作用が明らかにされた。
また，沖帯だけでなく沿岸域の水草帯の動物プランクトン群集も調査され，水草帯が複雑な環境を作ること，それが動物プランクトン群集組成に影響を与えることが示された。
これらの結果から，諏訪湖の動物プランクトン群集には高い魚の捕食圧がかかっていること，夏の食物連鎖では腐植植物連鎖が卓越していることが指摘された。
キーワード：諏訪湖，動物プランクトン，群集構造，生物間相互作用
Special issue: Studies on the organic community in Lake Suwa
[ Review ]
Zooplankton community in Lake Suwa: Community structure and its role in the ecosystem
Takayuki HANAZATO1), Takashi ARAKAWA2), Masataka SAKUMA1), Kwang-Hyeon CHANG1) and Tokio OKINO3)
1)Reserch and Education Center for Inlandwater Environment,
Shinshu University, 5-2-4 Kogandori, Suwa 392-0027, Japan
2)Saku Chosei High School, 951 Iwamurada, Saku 385-0022, Japan
3)Faculty of Science, Shinshu University, 3-1-1 Asahi, Matsumoto 390-8621, Japan
Abstract
Studies on the zooplankton community in Lake Suwa since the 1960s are reviewed, and the role of zooplankton in the lake ecosystem is discussed.
The community is dominated by rotifers in spring and by small cladocerans in summer and fall.
It seems that the zooplankton community structure has not been changed markedly since the 1960s.
Two Bosmina species, B.longirostris and B.fatalis, show seasonal and reciprocal succession:
the dominance of B. longirostris occurs in spring and fall and that of B. fatalis in summer.
The summer dominance of B. fatalis has positive correlations with the mean summer water temperature and the mean summer chlorphyll a concenration, suggesting that it is induced by the occurrence of the cyanobacterium Microcystis bloom.
Voluminous enclosures were set up in the lake, and experiments were conduced with them to understand the mechanisms maintaiming the lake ecosystem.
Results of the experiments have shown some important biological interactions related to zooplankton, such as predator-prey relationships and competition.
In Lake Suwa, not only the pelagic commuity but also the community in vegetation areas has been studied.
These studies have demonstrated that environment is highly diverse in the vegetation area, and that the zooplankton community acheves a higher species richness in the vegetation area than in the pelagic one.
It is suggested that the zooplankton community in Lake Suwa is exposed to heavy predation pressure by planktivorous fish, and that the major food chain from primary producer to zooplankton in summer is a detrius food chain.Key words: Lake Suwa, zooplankton, community structure, biological interactions
E-mail (T.Hanazato) : hanazato@po5.lcv.ne.jp
短報
都市湧水・真姿の池における従属栄養細菌群集の動態におよぼす降雨の影響
永翁 一代・森川 和子
摘要
武蔵野台地にある都市湧水・真姿の池において，1999年6月より9月まで梅雨期を中心に採水を行い，従属栄養細菌数(CFU)と環境要因の調査を行った。
調査期間中，水温は16℃で一定であり，pHは6.2〜7.0，ECは179〜201μS cm-1の間で変動した。
CFUは3.2×10〜7.9×102 CFU mL-1の間で変動し，変動パターンは降雨に遅れて増加し，その後減少する傾向がみられた。
湧水量は調査日までの40日間積算降水量と有意の相関を示した。
Cl-，NO3-，SO42-，Na+，Mg2+，Ca2+のイオン濃度と40日間積算降水量の変動は，負の相関を示した。
これに対し，CFUは，40日間積算降水量の変動と正の相関を示した。
これらの結果は，CFUの変動は溶存イオンのように単に水量に希釈されて変動しているのではない事を示している。
真姿の池湧水の従属栄養細菌は，積算降水量の増加に伴う地下水量や流速の増加にともない，土壌や帯水層堆積物から流入して増加していることが示唆された。キーワード：従属栄養細菌数，湧水，積算降水量
[ Note ]
Influence of rainfall on the bacterial community at the Urban spring Masugatanoike
Kazuyo NAGAOSA and Kazuko MORIKAWA
Tokyo University of Agriculture and Technology,
Saiwaicho 3-5-8, Fuchu, Tokyo 183-8509, Japan
Abstract
Fluctuations in the density of heterotrophic bacteria (colony forming units: CFU) and environmental factors were studied from June to September 1999 at the urban spring Masugatanoike in the southern Musasino upland of Tokyo, Japan.
Water temperature was constant at 16℃, pH ranged from 6.2 to 7.0, and EC fluctuated between 179 and 201μS cm-1.
The CFU in water fluctuated between 3.2×10 and 7.9×102CFU mL-1, increasing after rainfall and then decreasing.
The discharge was correlated to the rainfall summed for 40 days before the sampling day.
Fluctuations in the concentrations of Cl-, NO3-, SO42-, Na+, Mg2+and Ca2+ have a negative associations with that of the rainfall summed for 40 days before the sampling day.
In contrast, the CFU fluctuations had a positive association with the rainfall summed for 40 days.
These results suggested that the CFU should not fluctuate by the dilution of rainfall.
The CFU in spring water at the Masugatanoike might have increased when the summed rainfall increased because of increasing heterotrophic bacteria originating from the aquifer or soil.Key words: heterotrophic bactera, springwater, summed rainfall
E-mail (K.Morikawa) : mic.eco@cc.tuat.ac.jp
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