著者

浜野 隼 木村 将士 加納 光樹

出版者

日仏海洋学会

雑誌

La mer (ISSN:05031540)

巻号頁・発行日

vol.60, no.3-4, pp.25-35, 2022-12-28 (Released:2023-01-14)

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Seasonal changes in upstream movements of fishes were examined in an irrigation ditch flowing into an inland-sea lake, Kitaura, Ibaraki Prefecture, eastern Japan, from April 2020 to March 2021. A total of 1,762 individuals representing 6 families and 12 species were collected using small fyke nets throughout the study period. The most abundant species were the gobiid Rhinogobius sp. OR(70.8% of the total number of individuals collected), the gobiid Gymnogo- bius urotaenia(22. 5%), the cobitid Misgurnus anguillicaudatus(2. 7%), the gobiid Tridentiger brevispinis(1.7%)and the cyprinid Gnathopogon elongatus elongatus(1.1%). Based on the body sizes, developmental stages and seasonal occurrence patterns of fishes sampled, it is highly likely that the irrigation ditch would be used as a place of temporary growth and spawning by several fishes including amphidromous gobiids.

著者

加納 光樹 横尾 俊博 河野 博

出版者

The Japanese-French Oceanographic Society

雑誌

La mer (ISSN:05031540)

巻号頁・発行日

vol.56, no.1-2, pp.1-10, 2018 (Released:2021-05-19)

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2003 年6 月上旬に多摩川河口干潟域(河口から0-4 km)のタイドプール55 か所(面積0.6-6.4 m²)で,魚類群集の空間的な変動を調査した。調査期間中に2 科11 種計1,838 個体が採集された。採集個体は体長50 mm 以下で,大半がハゼ科の稚魚と成魚であった。採集個体数が最も多かったのはマハゼで全採集個体数の52.2% を占め,次いで,マサゴハゼ(24.6%),エドハゼ(12.7%),ビリンゴ(7.0%),ボラ(1.0%),ヒメハゼ(0.9%),アベハゼ(0.7%),ヒモハゼ(0.5%)であった。これらのうち,ビリンゴとボラを除く底生性ハゼ類6 種の生息密度は,河口域上部,中部,下部の間で異なっていた。各タイドプールにおける優占種の密度に基づく正準相関分析によって,魚類群集構造の時空間的変動は,アナジャコ類巣穴の密度,底質の中央粒径,塩分,干潮時の汀線からの高さ,水温,プール面積,水深とよく関連付けられることが明らかとなった。

著者

奥村 裕

出版者

日仏海洋学会

雑誌

La mer (ISSN:05031540)

巻号頁・発行日

vol.60, no.3-4, pp.37-42, 2022-12-28 (Released:2023-01-17)

著者

坂田 晴香 中川 耕三 北澤 健二 山本 澪 森 航大 高柳 和史 菊田 昌義 合田 賀彦 立花 義裕

出版者

日仏海洋学会

雑誌

La mer (ISSN:05031540)

巻号頁・発行日

vol.59, no.3-4, pp.79-100, 2022 (Released:2022-06-27)

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Using data collected from 2004 to 2018, the relationships between fluctuation in water quality and river loads were analyzed in eight areas within Osaka Bay, comprising the A-, B-, and C-type areas as designated by the chemical oxygen demand(COD)environmental quality standards. Different trends were confirmed in each area, related to their location in the bay. Decreasing COD concentrations were observed around the Muko River mouth, while concentrations near the Yodo River mouth, near the Yamato River mouth, and in areas at the center of the bay remained unchanged. These stable trends might be attributable to the high COD concentrations in the inflow water at the inner part of the bay, as well as the in situ COD production in the center of the bay. In summary, changes in water quality reflecting river loads were observed in the inner part of the bay, but the effect decreased toward the center of the bay where in situ production might be greater. Therefore, for the future restoration plan in Osaka Bay, different approaches will be required, depending on the characteristics of the individual sea areas.