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

佐々木忠義編

出版者

日仏海洋学会

巻号頁・発行日

1978

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.