The present paper deals with the ecological studies of the dragonflies of Lake Biwa, from 1962 to 1963. As the larvae of many dragonflies emerge in spring and summer, the exuviae were collected in those seasons. In autumn and winter, the dragnet was used for the collection of the larvae. Sampling stations are shown in Figs 1,2. 1. About 16 species of dragonflies were found in this lake, and Gomphus was most abundant. 2. In summer the exuviae of Gomphus oculatus and G. annulatus were most abundant, followed by those of Epophthalmia elegans and Ictinogomphus clavaius in this order. The percentage of the exuviae collected at all the surveyed stations is as follows : G. oculatus 56 per cent, G. annulatus 18 per cent, Ictinogomphus clavatus 14 per cent, Epophthalmia elegans 6 per cent. The distribution of G. oculatus and G. annulatus is shown in Fig. 3. At the shore where the littoral region is large, the number of exuviae is large and where the littoral region is small, the number of exuviae is small. 3. Many of the 12 species of dragonflies found in the south basin of the lake, were mostly lenitic species. The exuviae were few along the Seta River. Sampling stations and distributions of the exuviae are ahown in Fig. 4. 4. In autumn in the case of Ictinogomphus clavatus and Epophthalmia elegans, mostly the larvae of the final stage were found. In the case of G. oculatus, the N-1 stage and N-4 stage were found. (The larvae of far younger stage are supposed to exist, but the mesh of the dragnet was too large to catch them.)

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17 species of dragonflies found in the Dainohara forest park from 2011 to 2012 are listed with collection data. They are 1 species of Lestidae, 1 species of Coenagrionidae, 1 species of Calopterygidae, 1 species of Platycnemididae, 1 species of Cordulegastridae, 1 species of Corduliidae, 1 species of Gomphidae 10 species of Libellulidae and their seasonal and annual occurrence in the area are recorded.

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　「河川水辺の国勢調査」で得られている底生無脊椎動物（底生動物）データの中から解析可能な108水系－724地点の定量調査データを選別し，「瀬」の全底生動物現存量（全現存量）について国内の頻度分布を求めるとともに，地点を河床勾配，底質，地方を基に区分し，全現存量の空間パターンを調べた。全地点を対象とした全現存量（湿重）の中央値は冬春期が19.56 g m^-2，夏秋期が10.04 g m^-2であった。こうした値は，瀬に限定すると国内で過去に示された値と大きな違いはない一方で，海外の値に比べて数倍大きかった。全現存量は小さい河床勾配（<1/1600）や底質の区分（泥や砂：<2 mm）の地点で最小で，中ほどの河床勾配（1/800－1/400）や底質（粗礫：5－10 cm）の区分までは区分が上がるとともに増加した。また，全現存量は北東日本（特に東北，関東，北陸）に比べて西南日本（特に中国，四国，九州）で大きく，これらの間には中央値で2.7－6.6倍の違いがあった。底生動物の多くの属が，全現存量が高い河床勾配や底質の区分に対して高い選好度（出現や生息密度を基に評価）を示し，またその生息密度と全現存量の間に正の相関を示した。造網性トビケラは，こうした傾向が最も顕著であり，また重量推定により全現存量に対する寄与が大きいと考えられた。全現存量と正の関係にあるこうした底生動物の生態を踏まえ，空隙量や安定性といった河床条件が瀬の全現存量に影響する重要な要因と考えられた。また，全現存量と属数の正の相関から，全現存量の大きい瀬では，特定の少数属が優占するのではなく，多くの属が共存している状態であることが示された。

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Faunal survey of dragonflies and damselflies in the Akasaka Imperial Garden, Tokyo, was conducted during 2012 to 2022, and recorded a total amount of 38 species including some species possibly occasionally came from outside (e.g. Anotogaster sieboldii). Previous study from 2002 to 2004 by Saitô et al., (2005) reported 24 Odonata species from the garden. In comparative with this record, additional 16 species are newly recorded by our survey but two species were not re-observed. Almost all the recorded species are lentic ones. It would be caused by the scarcity of lotic environment in the garden. A total of 12 threatened species ranked in the red list concerned with the biota of Tokyo (Natural Environment Division, Bureau of Environment, Tokyo Metropolitan Government, 2023) is found. This result could be one of rationales for the continued preservation of the Akasaka Imperial Garden, one of precious urban greens in the Tokyo metropolitan area.

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Before the Ise-wan Typhoon (September 1959), the Yoshino River (Nara Prefecture) had the largest standing crops of aquatic insects known in Japanese streams. However, the aquatic insect communities were destroyed considerably by the Typhoon. We studied this river in September 1963,four years after the Typhoon, and wish to report the results and to compare them with the data of TSUDA and GOSE (1953,1954), who studied this river in 1953,six years before the Typhoon. The results are summarized as follows : 1. In August 1953,six years before Ise-wan Typhoon, the standing crop of the station "Koshibe" was 32 g per 0.25m^2 in a wet sample. But in September 1963 the standing crop of this station was only 0.5g. Also the other stations had far less standing crops in 1963 than in 1953. 2. In 1953,the net-spinner's percentage ("net-spinner's percentage" means the rate of the weight of the net-spinners to the total weight of benthic insects) of the station "Koshibe" and the station "Kawaraya" were 80〜95 per cent. But in 1963,the net-spinners percentage were 42〜73 per cent, and the percentage of the creepers were more in 1963 than in 1953. 3. In 1953,among the net-spinners Parastenopsyche sauteri (Stenopsychidae) was dominant in this river. In 1963,however, Hydropsyche ulmeri (Hydropsychidae) was dominant in the same river.

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In the winter of 1964,the author studied on the aquatic insect communities of the lower parts of seven rivers flowing into Lake Biwa, and calculated the biotic index based on the BECK-TSUDA method. The author wishes here to report the results and to compare them with the data of the investigation of the summer of 1963. The results are summarized as follows : 1. The temperature of the river water in winter (at the time of the sampling) does not exceed 11℃ in the lower part of the seven rivers, while that in summer (at the time of the sampling) exceeded 20℃. The pH value was 7.0〜8.3. 2. In the seven rivers, the fauna of the aquatic insects differed between in winter and in summer. 3. Three rivers (Yogo River, Hino River and Ishida River) had richer standing crop of aquatic insects in winter than in summer. But in four rivers (Ado River, Chinai River, Okawa River and Ane River), the standing crop was nearly equal in both seasons. 4. In the seven rivers, the rate of the standing crop of each life form differed between in winter and in summer. 5. In the three rivers (Yogo River, Okawa River and Hino River), a higher biotic index was obtained in winter than in summer for various reasons.

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多摩川水系の農業水路において，リーチ内の瀬－淵および微生息場所が水生昆虫の多様性に及ぼす効果を検証した。その結果，リーチ内のα多様性とβ多様性はランダムに生じるものと有意な差はなく，また種組成の顕著な差異も見られなかった。とくに瀬特有の種組成の発達が見られず，農業水路の掃流力の小ささや土砂供給の多さがその要因として推察された。このため，掃流力が大きい河床勾配の大きい区間の保全が重要であることが考えられた。また，農業水路の水生昆虫群集の保全にはより上位の生息場の階層である水路周辺の土地利用や河川との位置関係のようなリーチ間に生じる多様性についてもさらなる検証が必要であると考えられた。

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We conducted a correspondence analysis (CA) of 88 species of Odonata (dragonflies) observed at 455 grid sites (ca. 0.5km×0.5km) in the Shimanto River basin and adjacent areas in Shikoku, Japan. Multiple regression analyses of the two main axes of the CA ordination on the geographical features (altitude, relief) and vegetation of grid sites indicated that the degree of relief and the areal proportion of paddy fields were the main determinants of the species distribution of Odonata. The species were classified into 5 groups by k-means clustering based on the coordinate axes. Groups I and II mostly consisted of lentic species inhabiting ponds, marshes and paddy fields of flat lands. Groups III and IV were composed of lentic species mainly inhabiting marshes and paddy fields and lotic species in slow streams. Group V consisted of lotic species inhabiting mountain streams and spring sources. Habitat requirements for the species appearing in the Red List of Kochi Prefecture are also discussed.

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The present paper deals with the ecological studies of aquatic communities of Okawa River, Yogo River, Ane River and Seri River which flow into the northeastern part of the Lake Biwa. The biotic index of the same rivers was determined based on the BECK-TSUDA method. The field study was made in spring (Seri River) and summer (other rivers) in 1963. The results are summarized as follows : 1. Okawa River and Yogo River had more standing crops of aquatic insects than Ane River and Seri River. But the mouth of Yogo River had less standing crop, the river being polluted by drainages of paddy fields and sewages. The lower part of Ane River which is polluted by wastes from a paper mill, had small standing crop. The lower part of Seri River which is polluted by sewages of Hikone City and besides dried up in winter, had also small standing crop. 2. The standing crop of each life form of aquatic insects is shown in Fig. 3. 3. The biotic indexes of the four rivers are shown in Fig. 4. In the lower parts of those rivers, a low biotic index is obtained because of various ill-effects.

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　本研究は都市河川の「子供の川遊び場」としての機能を生物に注目して評価することを目的とした．愛媛県松山市の都市域を流れる河川に設定した24地点の調査地にて，子供が実施可能な方法により生物調査を行い，子供にとって魅力的な生物（魅力種）の生息状況を把握した．この結果，25種，1391個体の魅力種が松山市都市域の河川に広く生息していた．水質が良好な小規模河川で魅力種の生息密度が高く，種数も多かった．魅力種の生息状況には，河川形状，水質劣化，さらには構成種の生態的特性が影響していることが示唆された．魅力種が多く生息する地点において，河川へのアプローチの改善や近隣住民への生物情報の周知などの方策を採ることにより，都市河川における子供にとっての親水性の向上が可能になるものと考えられた．

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Oxygen is less available in water than in air because of its low solubility and heterogenous distribution. Larvae of Ephemeroptera, Odonata, Plecoptera, Megaloptera, Trichoptera, and aquatic Diptera generally use dissolved oxygen for respiration. In this review, respiratory responses of these aquatic insects to low oxygen conditions are compared in relation to their habitat differences. The species inhabiting relatively low oxygen environments regulate their respiratory rates against hypoxia, but the respiratory rates of riffle-dwelling species are decreased with the decline of oxygen concentration. To compensate respiratory rates, the following are important characteristics : (1) gill development, (2) gill beating, (3) respiratory movement (undulation or ventilation), (4) respiratory pigments (erythrocruorin or haemoglobin), (5) anaerobic metabolism, (6) bimodal breathing (aquatic and aerial respirations), and (7) microhabitat shift. In order to further discuss the speciation processes that produce diverse respiratory characteristics, much more research is needed, especially to find variation in respiratory characteristics within a population or between populations and to examine whether the variation has a genetic basis or not.

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1.背景と目的；2.方法；3.結果；3-1.結果概要 ；3-2.各種の分布状況；3-3.1990年代と2010年代のトンボ分布比較（分布変遷）；3-4.調査者によるテーマ解説・記録（1990年代の滋賀県のトンボ調査とその後；オオサカサナエは、なぜ琵琶湖の白ひげ浜に生まれるのか?；キイロヤマトンボ生息地での観察；滋賀県のカトリヤンマ ；マダラナニワトンボの観察；大津市伊香立のアキアカネ；ノシメトンボの大繁栄と衰退；滋賀県立大学のトンボ；湖西・湖北のトンボ探し；鏡山周辺のトンボ探し；御池岳の山岳池にトンボを追う!；色々な生き物とかかわってきて；みなくち子どもの森のトンボ）；4.結論および提言；5.データ

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東京都練馬区にある東京都立石神井公園周辺の1930〜40年代と1980〜90年代における生物相を50余点の文献から明らかにした.また,同地のランドスケープを地図と空中写真を用いて縮尺1/2,500で図化した.2つの年代間で生物相の比較を行ったところ,すべての分類群で種の多様性が顕著に低下していることが明らかになった.また,ランドスケープの変化を地理情報システムによって分析した結果,樹林地は比較的高い率で残存していたものの,草地,湿地は大きく減少し,水路などの流水域と湧水はほぼ完全に消失していた.開放水面の面積は微増し,市街地は大幅に増加していた.同地域における種多様性の変化要因を明らかにするためにギルド別の種数変化と生育(息)地の規模変化の関係を求めた結果,種数の変化は生育(息)地の規模変化に対応していることが認められた.また,ギルドによって,生育(息)地の分断化に対する抵抗性に差異が認められた.研究の結果,地域において種多様性を保全するためには,生育(息)地として機能するランドスケープ要素(生態系)の多様性を確保することが不可欠であることが示唆された.

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