2001年7月2日から9月18日まで石狩川で採集したシジミ (天然.) と, 別に石狩川で採取したシジミ (地場産貝) と網走湖産の種苗 (種苗貝) を産卵直前に塩分濃度を5psuに高めた水槽で飼育したシジミを標本として用い, 軟体部指数と卵巣熟度から産卵期と産卵条件について調査した。その結果, 軟体部指数の低下は, 天然貝は7月下旬～8月中旬, 地場産貝は7月下旬～8月下旬, 種苗貝は8月中旬～8月下旬にそれぞれみられた。卵巣熟度から産卵個体がみられたのは, 天然貝と地場産貝は7月下旬～9月上旬, 種苗貝は8月下旬～9月上旬であったので, 石狩川のシジミの産卵期は7月下旬～9月上旬であった。本年夏期の石狩川の水温は全般に低く, 塩分も1.4psu以下で, 産卵期間中は未放卵の成熟期の個体が常にみられたことから, 塩分では特に厳しい環境条件の下で産卵が行われていると推察された。

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Lake Ogawara, located in Northern Japan, is a brackish lake with the surface-area of 63km^2. The maximum depth is about 25m, and approximately 12psu of salt water exists in a lower layer under the depth of 20m throughout the year. Lots of Corbicula Japonica are living in the lake, and about 2500 tons are taken out as fishery product. We develop an ecological model to consider the biochemical processes of the bivalve, that calculates water temperature, salinity, chlorophyll-a, inorganic nitrogen and phosphorous, organic nitrogen and phosphorous, COD and dissolved oxygen. We make one-dimensional calculations to clarify the seasonal variabilities in water qualities and nutrients cycle, and use a three-dimensional hydrodynamic model coupled with the ecological model to clarify the spatial distributions of water qualities. It is found that an increase of nutrient supply from the lower layer, caused by the intense vertical mixing, makes phytoplankton blooming active, and that the spatial distribution of the phytoplankton greatly depends on the habitat distribution of Corbicula Japonica. The calculation results for the nutrients cycle show that the amount of phosphorous consumed at primary production is more dependent on the biochemical and physical processes occurred in the lake than the inflow load supply. About 20% of primary production is ingested by Corbicula Japonica, and its purifying function is about 30% for COD. Because Corbicula Japonica stores nitrogen internally, the concentration of total nitrogen in the lake water is restrained and decreases in October in spite of the time of the maximum primary production.

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むき身の水抽出液から, 硫安塩析, アフィニティー, 吸着およびイオン交換カラムクロマトグラフィーによりリゾチームを精製した。精製品はPAGEにおいて単一なバンドを示し, SDS-PAGEにより分子量12,000と見積もられた。本酵素の最適pHは4.8,最適温度は70℃, pH3.0-6.8で安定であり, pH4.8では90℃, 30分の加熱後も80%の活性を保持した。また, 本酵素はMicrococcus lysodeikticusを基質とした場合, ニワトリ卵白リゾチームより256倍高い比活性を示した。本酵素とニワトリ卵白リゾチームのアミノ酸組成は異なり, またN-末端アミノ酸配列の相同性は非常に低かった。

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ホタテガイ (養殖および地蒔き), マガキ (養殖), アサリ, , サザエ, ウバガイ, サルボウ, アコヤガイ (真珠養殖) の個体群を対象に, 炭素収支による生物機能の全国評価を行なった結果. 8種の生物量は1.7Mt (143ktC) あり, 炭素収支は排出が420ktC/y, 固定が467ktC/yで, 差し引き年間47ktCの炭素が貝類によって固定される. 有機物を固定する機能は生物量の大きいホタテガイが卓越し, 水中懸濁物の除去機能はアサリが最も大きい. 海区別では, 生物量の大きいオホーツク海区に次いで富栄養化の進んだ太平洋中区と養殖主体の瀬戸内海区における炭素の排出と固定が大きい.

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The environment of the brackish lakes on the coast of the Sea of Okhotsk, in Hokkaido, has changed dramatically due to increased human activities since the Meiji period. Previous paleoenvironmental studies of these lakes have revealed historical changes in the lake topography and ecosystems over the last 10000 years. However, few studies have focused on recent environmental changes in these lakes, especially owing to the high economic growth in the region from the 1960s to the present. The purpose of this study was to examine change in the lake environment and aquatic organisms in Lake Shibunotsunai and Lake Mokoto, since 1945, by conducting field surveys as well as using existing data. From 1945 to the early 1960s, there was little human impact on the lake environment. However, since the 1960s, the lake environment has changed rapidly, mainly due to the progressive construction work on the inflow river channel and outflow channel from the lakes to the sea. Furthermore, changes in land use have led to eutrophication of the lake water and an influx of large amounts of mud in the lakes, making them shallower and smaller. Such changes in the lake environment have had a strong impact on the abundance and fishery activity of the brackish water clam Corbicula japonica in both lakes. Further studies of core samples from Lake Shibunotsunai are necessary to corroborate the results of this study.

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　河口域の保全，修復のためには，対象とする場の潜在的な生物相やハビタットを把握する必要がある．本研究は，河口域保全のための基礎的な情報として，全国一級河川の河口域を対象に，底生動物の生物地理に基づくEcoregionを設定し，同一Ecoregion内で物理指標による河口域の類型化を行った．底生動物相の類似度から日本の河口域は，日本海，太平洋，西南海の3つのEcoregionに区分された．また，各Ecoregionの指標種と関係の強い物理環境要因として，波浪，潮汐，河川のエネルギーを代表する指標が選択された．これらの指標を用い日本の河口域を9つの河口タイプに分類した．同一分類に属する河口域は潜在的な生物相とハビタットが相同とみなせるため，分類結果は河川生態系保全の基礎単位となりうる．

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The compositions of sterols of snails and bivalves were determined. In this study, six species of marine snails, two species of fresh-water snails, two species of marine bivalves, fresh-water and brackish-water bivalve were examined.
The unsaponifiable matter was acetylated and separated in to several fractions by silver nitrateimpregnated silicic acid column chromatography. Sterol composition of each fraction was determined by GLC.
It was shown that the sterol composition of snails, fresh-water and brackish-water bivalves is different from that of marine bivalves. Cholesterol was 7090% in snails, 6070% in fresh-water and brackish-water bivalves, and 3040% in marine bivalves.
UV absorption spectra showed the presence of Δ^{5, 7}-sterol in these mollusks, and 7-dehydrochole-sterol was isolated. C₂₉-sterols showed the difference with the species of mollusks.

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We carried out a demonstration experiment using the Intertidal Flat Experimental Facility (IFEF), which is a semi-closed and experimental intertidal flat ecosystem, to investigate the effects of hypoxia and hydrogen sulfide (H_2S) water on organisms and water quality. We created three tide pools on the experiment tidal flat and divided them into three experiment areas : one area where sodium sulfide (Na_2S) was added to examine the effect of hypoxic water alone; another area where hydrogen chloride (HCl) and sodium sulfide (Na_2S) were added to examine the effect of both hypoxic and hydrogen sulfide (H_2S); and a control area where nothing was added. Then we observed changes in the water quality and the survival situation of the benthic organisms in each area. The results indicated a possibility that the mortality of organisms increases due to a combination of factors, i.e. hypoxic water and high hydrogen sulfide and high water temperature (>20℃). The results also suggested a possibility that in a tidal flat, where the sea level changes frequently, the length of time that organisms are exposed to two factors, i.e. hypoxic water and high hydrogen sulfide, is short, and therefore the mortality can be avoided.

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　大阪湾奥部に位置する堺泉北港堺２区に，海域の環境改善の一方策として３タイプの生物共生型の護岸を実験的に設置した．水質調査および生物調査を設置後から６年間にわたって実施した．実験海域の水質は８月から９月にかけて底層から水深2 mまで貧酸素化する程，富栄養化が進行していた．実験水域は生物生息には厳しい水環境であるにもかかわらず，生物共生型護岸の設置１年目から生物が加入した．準絶滅危惧種のホソアヤギヌ（海藻）や（貝類），ウナギやアユ等の幼稚魚が加入した．また，６年経過後もその生物生息場としての機能を維持していた．

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It's common knowledge that the artificial creation of shallows including tidal flats has great water purification function. Therefore, creating tidal flats in Mikawa Bay of Japan, we believe it is important to choose areas that will be the most effective for the recruitment and/or supply of pelagic larvae. Firstly, we selected the short-necked clam (Ruditapes philippinarum) as a target species, and used a receptor mode model to predict trajectories of the pelagic larvae flow towards the Isshiki tidal flat areas. The results show that: (1) The main sources of larvae supplied to this area are the inner parts of the bay: (2) The trace routes vary greatly with temporal wind-induced currents and vertical distribution of the larvae. Secondly, we tried to map the important areas that are sources of larvae by predicting trajectories from 5 areas in Mikawa Bay. Based on the results, the supply patterns to each area were placed into 2 major patterns: self-contained pattern and ingression pattern. From these simulations, we found that the receptor mode model used in this study has been useful in answering some of the difficult questions faced in restoring bay environment, when determining the best location for creating artificial shallows.

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