における青潮発生の物理的なメカニズムを明らかにするため，2007～2008年に実施した現場観測結果にもとづき，数値モデルCOSMOS を用いて密度流による水塊移動と風の条件を組み合わせた数値実験を行った．実験に用いた数値モデルは，2008年の春季から秋季までのの物理環境を精度良く再現できていた．実験の結果，夏から秋への季節遷移期に湾口部の海水は湾中央部底層へ進入し始めた後，およそ11日で湾奥部まで到達していたことがわかった．また，湾口部水の底層進入後に風の効果を無くした実験により，湾奥部に密度流の効果による鉛直上向きの流れが見られること，さらに，底層進入の開始後に風速3～4m s－1の南東風を吹かせた実験により，湾中央部底層の水塊の湾奥部表層への輸送に風と密度流の両方の効果が寄与していることがわかった．以上のことから，の奥部における青潮発生を予測するためには，湾口部水の底層進入開始のタイミングとその後の風の状況を知ることがきわめて重要と考えられる．

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【目的】飛行機目視調査により，小型鯨類スナメリの個体数を推定する． 【方法】ライントランセクト法にもとづく調査を，日本におけるスナメリの 5主分布域のうち 2海域（有明海・橘湾，）で行なった．調査方法は Yoshida et al. （1998）によった．本種の岸よりの分布（Kasuya and Kureha, 1979）を考慮し，緯度線に平行な調査コース（海岸線に対しほぼ垂直）を，有明海と橘湾に 1マイル間隔，に 0.5マイル間隔で設置した．設置数はそれぞれ 42本，16本，26本で，調査時に有明海では 3本に 1本を，橘湾とでは 2本に 1本を，系統抽出し航行した．2名の観察者が小型セスナ機に乗り込み，線上を高度 150ｍ，時速 90ノットで飛行し，それぞれ調査線の片側（横距離 50-450ｍの間）を探索した．スナメリの群発見時には，位置，時刻，横距離（高度と発見された群に対する伏角から計算），頭数等を記録した．海面反射が探索に与える影響を除くため，調査コースの南側での発見は解析に加えなかった．機体下方向の見落としを考慮し，横距離 80m以遠での発見のみ用いた．Beaufort風力階級 3以上での発見は除いた．小川ら（2013）に準じた有効探索幅をもとに，個体数を推定した． 【結果】2012年 8月 8日に有明海を，9日に橘湾とを調査した．ともに全域にわたり Beaufort風力階級 2以下の環境であった．有明海では，295.8kmを飛行する間に 75群 100頭を発見した．発見は湾央に集中し，湾奥と湾口でなかった．調査後，帰還時に橘湾央で 6群７頭の二次的発見を得た．橘湾では 224.1kmを飛行する間に湾の西端で 1群 1頭を，では 186.6kmを飛行する間に 20群21頭を発見した．での発見は，全域にわたっていた．帰還時に橘湾央を飛行したが，二次的発見はなかった．個体数は，有明海で 2,963頭（密度 =1.9頭/km²，CV=24.8%），橘湾で 37頭（0.04，103.2%），計 3,000頭（1.2，24.5%），で 168頭（0.5，39.3%）と推定された．

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Omura Bay in Nagasaki Prefecture, which is connected with the open sea through Sasebo Bay, is called a double-closed bay. It is also an obstacle for a tidal current of Omura Bay that there are very narrow channels between these bays. Satellite remote sensing technique was applied to the visualization of the seawater plume in Omura Bay. The plumes show the current from surface to the depth of a few meters, as Landsat5/TM data have relation to the seawater quality in the same area. The plumes were investigated with the tide of the bay. It follows that the direction of incoming seawater is the same as the topographical direction of Hario Channel, and that there is a tidal residual current between Hario Channel and Ohsaki Peninsula. Lastly the observation by using current meters was also shown to back up these movements of the plumes.

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Omura Bay is located in the central part of Nagasaki Prefecture and is connected with the open sea through Sasebo Bay by two narrow straits. Therefore movement of the bay water is very stagnant and oxygen-deficient water masses are formed at the bottom layer in the central part of the bay every summer.
We have been measuring the concentrations of phosphorus in this bay for twelve years.
The concentrations of total phosphorus in the surface layer began to increase gradually after 1992.
The concentrations in the whole bay become about 10 μg·l^-1 higher after September than those in the earlier months every year. It is thought that orthophosphate in the bottom layer at the central part of the bay, which was released from the bottom sediment in summer, causes the increase of total phosphorus in the surface layer after September. This water mass which has been enriched by ortophosphate (as total phosphorus : 70-100 μg·l^-1) is diffused by circulation owing to the drop in water temperature of the surface layer and mixing by wind, and the concentration of total phosphorus in the surface layer will rise.

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In the present paper, the authors tried to estimate the influx loads into a double-closed bay (Omura Bay) using forty-nine scenes of Landsat5/TM from 1984 to 2000, and statistical data for many years. From the TM data, NDVI (Normalized Difference Vegetation Index) values were calculated for four seasons in each year. The outcomes without sea areas were classified into five categories, which were water region (pond, lake, etc.), forest area, agricultural land (plow land and paddy field), uncovered ground, and urban area. The influx loads were calculated from the total of surface areas of each category and the statistical data in each year. The relationship between the influx loads and the sea water quality changes of the bay was evaluated. Adequate correlation was estimated between phosphorus and nitrogen influx load, which were calculated from TM data, and the actual values of total phosphorus and nitrogen in the bay, respectively. However, in the case of COD and chlorophyll-a values, mutual relationships were not estimated from the results.

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本研究は, 二重閉鎖性湾である長崎県のを例に, 湾内で実測された潮位などの情報を利用して, 特定日時の過渡的な流動状態を再現するシミュレーション・システムの開発を行うものである. このシステムは, 内部に持つ潮位の自動制御機能により, 常に最適な強制水位を自動的に算出しながら目的のシミュレーションを継続できるシステムであり, 従来の数値シミュレーションとは異なり, 潮汐調和定数などが未知の海域でも開境界に選べるなどの特徴を持っている. また, 本論では, このシステムの性能評価を実施し, 入力した湾内の潮位振幅に対して, シミュレーション結果の潮位振幅の再現性が100%に近いことなどを確認した.

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ハマボウはアオイ科の落葉低木で,関東地方南部以西の本州,四国,九州と韓国済州島に分布し,河口付近や入り江などの塩湿地やその周辺に生育し,純群落を形成する.近年は河川改修や埋め立てなどによって生育地が少なくなり,個体群が孤立化したり,群落が縮小化している.本研究はハマボウの花と果実の形質を調べ,個体群多様性の重要性を明らかにする目的で行ったものである.調査は長崎県の西彼杵半島の東側に位置する沿岸の5つの個体群と,外海側に位置する半島の西側の4つの個体群を対象に行った.各個体群から5つの個体をランダムに選び,計45個体について,各個体から30ずつの花と果実を採集し,形質を調べ,比較した.測定した形質は,花弁長,花弁幅,花柱長,葯-柱頭距離,葯-葯距離,雄蕊数,果実長,果実径,1果実あたりの潜在的な種子数(胚珠数)である.その結果,同一個体群内において各個体はそれぞれ特徴的な形質をもっているが,形質によっては差がないものもあった.しかし,個体群間ではすべての形質において差が認められた.側個体群と外海側個体群とを比較すると,側個体群の方が,花弁長,花弁幅,葯-葯距離,果実長,果実径,1果実あたりの潜在的な種子数において値が小さかったが,葯-柱頭距離は値が大きかった.また,花柱長と雄蕊数は有意な差はなかった.は超閉鎖性の湾で,約7000年前に湖と海とが繋がり,海水が流入して成立したもので,海水が外海から流入した際に,湾外のハマボウが侵入し,側に拡がっていったものと考えられ,現在は隔離状態にある.側の個体群の形質の特徴は,ポリネーターが豊富な環境の下で,自花受粉をさけるように進化した可能性を示している.ハマボウ群落の保全や植生復元には,個体群レベルで考慮する必要があると考えられる.

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Man-made perturbation on the environment has resulted in many problems such as eutrophication and sedimentation in water bodies. In recent years, domestic sewage and industrial waste water are having a bad infuluence on water quality, especially, estury and closed bay area. Therefore, water quality controlling and monitoring activities are inevitable.
We tried to apply satellite remote sensing techniques to investigate the sea water exchange of the Omura Bay and the Sasebo Bay. Maximum likelihood method was used to classify and confirm the exchange condition of sea water bodies. And also, the result are compared with an outcome of numerical simulation methode by workstation computer.

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In recent years, domestic sewage and industrial waste water are having a bad influence on water Quality of the Omura Bay in Nagasaki prefecture. Therefore it is need to monitor water quality and clean up the Omura Bay. In this paper, sea water of satellite observation are classified into water of the Omura Bay and water of the Sasebo Bay by maximum likelihood method, and currents of the Omura Bay are investigated. And the result are compared with currents in a hydrogeological model of the Omura Bay.

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における貧酸素水塊の消滅過程の詳細を明らかにするため，2009年の夏季から秋季にかけて集中的に実施された，水温・塩分・溶存酸素（DO）の分布に関する観測（原則として週1回）と流向流速・水温・DO の係留観測などの データ解析，並びに熱収支に関する解析を行い，消滅期の海洋構造の三次元的な変化とその要因について検討を加えた．その結果，底層の貧酸素水塊は，2009年8月下旬～9月上旬は北部～湾中央部に広く分布し，9月中旬～下旬は主に湾奥部（南東部や北東部）に分布していたことが分かった．9月上旬～中旬の貧酸素水塊の分布の変化に対する吹送流の補償流の寄与は小さく，主に湾口部の底層から流入する密度流によるものと推定された．また，貧酸素水塊の分布が変化してから，海面冷却に伴う鉛直対流により貧酸素水塊が完全に消滅するまでには，およそ1カ月の時間差があった．近年のにおける青潮の発生時期は9月～10月初めに集中しており，上記のように初秋に底層に生じる密度流により，貧酸素水塊が湾中央部から湾奥部に移動することが，青潮発生の前提条件になっている可能性が高いと考えられる．

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This paper consists of three parts. At first, the authors applied satellite remote sensing technique to investigate the ocean current of the Omura and Sasebo Bays in Nagasaki Prefecture. Maximum likelihood method was used to classify and confirm the exchange condition of sea water bodies. Secondarily, numerical simulation system with three-element control function was developed. This system is able to simulate tide which is shown on tide table. At last, the results of satellite remote sensing were compared with the outcome of numerical simulation system.

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Omura Bay in Nagasaki Prefecture, which is called a double-closed bay, is connected with Sasebo Bay through very narrow channels. The authors had applied satellite remote sensing technique to confirm the exchange condition of seawater between these bays. This method is capable of investigating only the surface current. In this paper, the numerical simulation system was improved in order to simulate actual tides by using three-element control function. The results of satellite remote sensing were compared with the outcome of the simulation system. It follows that the results of satellite remote sensing and the outcome of the system corresponded well when the axis of coordinates which is rotated 34 degrees from circles of latitude and longitude and eddy viscosity in the 40m2/s to 60m2/s range were used for the numerical simulation.

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The authors had tried to apply satellite remote sensing techniques to investigatethe sea water exchange of the Omura and Sasebo Bay. Maximum likelihood method wasused to classify and confirm the exchange condition of sea water bodies. They arenow developing a numerical simulation system which have a three element-controlfunction, and also trying to simulate a tidal current of the Omura Bay by developedsystem. The results of satellite remote sensing are compared with the outcome ofnumerical simulation.

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The Omura Bay is situated in the central part of Nagasaki Prefecture, which yields many problems including traffic one between both the northern and southern parts and the eastern and western parts of the Prefecture.In this paper the authors proposed a concept of the Omura Bay Bridge in order to solve these problems, and considered on the concept from engineering point of view. Discussions werefocused on environmental, bathymetric and soil surveys, route location, bridge type and others. As the type of bridge, a pontoon type was considered to be more prominent than the other types owing to its working period and cost shortage, and if this type bridge were built here the Omura Bay Bridge will be welcomed to be a tourist route as the first one in this type in Japan.

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Omura Bay in Nagasaki Prefecture, which is almost isolated from the outer sea, is famous for the very low exchange rate of sea water. In the present paper, the authors carry out the tidal flow simulation using the simulation system improved with the automatic control method, and it is discussed that the effect of seabed configuration on the exchange rate of sea water in Omura Bay. At first, it was estimated that the current rate ranges from 0.2 to 0.4%. Secondly, the authors performed the simulation tests with the modified seabed configuration which is cut the sea mount and buried the deep basin, respectively or simultaneously. It was confirmed that there are little changes of tide, the averaged rates become higher than current one and the water mass pattern nearby the bay mouth stretches into the depths of the bay.

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Hypoxia extending over the bottom water every year during summer involves Ohmura Bay in a serious environmental issue. Rise and fall of the hypoxic water mass was simulated with a 3D numerical eco-hydrodynamic model in order to investigate the relation with the influencing factors. The result shows that increased stratification during July-September induces and develops hypoxia in the bottom layer from June to mid-August by limiting vertical transport of oxygen. The benthic hypoxia reaches the highest stage in mid-August, then begins to decline gradually afterwards but lasts until early October. The recovery process of oxygen turned out to be closely related with change in the pathway of oceanic water intrusion into the central basin. After September, the oceanic water with rich oxygen begins to flow directly into the central basin, contributing toward alleviation of the hypoxia. Episodic wind event enhances vertical mixing and destroys the bottom hypoxic water quickly but only intermittently: hypoxia comes back and covers the seabed again immediately after the wind ceases. It is only a strong northerly wind caused by a tropical storm in the early stage of October that leads it to a termination every year.

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