DSpace Collection: 2017-12-28
http://hdl.handle.net/2115/68158
2017-12-282024-03-29T05:46:42Z海底耕耘を活用した Chattonella 赤潮制御の試み
http://hdl.handle.net/2115/68161
Title: 海底耕耘を活用した Chattonella 赤潮制御の試み
Authors: 今井, 一郎; 各務, 彰記; 小原, 静夏; 結城, 貴志; 小池, 一彦; 萩原, 悦子; 小川, 憲太; 米山, 弘行
Abstract: Diatoms are the most predominant phytoplankton group in the coastal sea and many planktonic diatom species produce resting stage cells in their life cycle to endure unfavorable conditions. These diatom resting stage cells play an important role in initiating the blooms. It is empirically known that diatom cells are sparse in water during the course of red tides of harmful flagellates such as dinoflagellates and raphidophytes. A promising strategy to control the occurrences of red tides by harmful flagellates is to artificially induce diatom blooms just before the development of red tides of harmful flagellates. There usually exist more than 10⁵ cells of diatom resting stage cells or more in 1-g bottom sediments of coastal water areas, but they need light for germination and rejuvenation to become planktonic form. Sediment perturbation was carried out to transfer diatom resting stage cells in bottom sediments to euphotic zone and to induce germination and rejuvenation. This trial was made using dragnet fishing boats in coastal sea area of Tomonoura, Fukuyama City, Hiroshima Prefecture, in July 2016. The densities of diatom resting stage cells were 2.8×10⁵g-1 wet sediment at the site(Stn. A, 4m depth) outside of the dragnet-trawling zone and 1.2×10⁵g-1 wet sediment at the site(Stn. B, 4m depth) in the trawling zone. The densities of planktonic diatoms increased in the water column at Stn. B just after the trawling, but not at Stn, A, and totally increased thereafter(maximum value of 1,383 cells mL-1). The cell densities of the raphidophyte Chattonella spp. decreased at Stns. A and B. The water sample after sediment perturbation was collected at 2 m deep at Stn. B, and incubation experiments were conducted for the bottles in combination with the inoculation of Chattonella antiqua(200 cells mL-1) and the strengthening of SWM-3 culture medium(1/100). Diatoms always increased and Chattonella cells decreased in all the experimental bottles. The present study demonstrated a possible feasibility of sediment perturbation as a environment-frendly control strategy for Chattonella red tides in coastal sea area with artificial induction of phytoplankton flora to diatom dominant communities.2017-12-27T15:00:00Z今井, 一郎各務, 彰記小原, 静夏結城, 貴志小池, 一彦萩原, 悦子小川, 憲太米山, 弘行Diatoms are the most predominant phytoplankton group in the coastal sea and many planktonic diatom species produce resting stage cells in their life cycle to endure unfavorable conditions. These diatom resting stage cells play an important role in initiating the blooms. It is empirically known that diatom cells are sparse in water during the course of red tides of harmful flagellates such as dinoflagellates and raphidophytes. A promising strategy to control the occurrences of red tides by harmful flagellates is to artificially induce diatom blooms just before the development of red tides of harmful flagellates. There usually exist more than 10⁵ cells of diatom resting stage cells or more in 1-g bottom sediments of coastal water areas, but they need light for germination and rejuvenation to become planktonic form. Sediment perturbation was carried out to transfer diatom resting stage cells in bottom sediments to euphotic zone and to induce germination and rejuvenation. This trial was made using dragnet fishing boats in coastal sea area of Tomonoura, Fukuyama City, Hiroshima Prefecture, in July 2016. The densities of diatom resting stage cells were 2.8×10⁵g-1 wet sediment at the site(Stn. A, 4m depth) outside of the dragnet-trawling zone and 1.2×10⁵g-1 wet sediment at the site(Stn. B, 4m depth) in the trawling zone. The densities of planktonic diatoms increased in the water column at Stn. B just after the trawling, but not at Stn, A, and totally increased thereafter(maximum value of 1,383 cells mL-1). The cell densities of the raphidophyte Chattonella spp. decreased at Stns. A and B. The water sample after sediment perturbation was collected at 2 m deep at Stn. B, and incubation experiments were conducted for the bottles in combination with the inoculation of Chattonella antiqua(200 cells mL-1) and the strengthening of SWM-3 culture medium(1/100). Diatoms always increased and Chattonella cells decreased in all the experimental bottles. The present study demonstrated a possible feasibility of sediment perturbation as a environment-frendly control strategy for Chattonella red tides in coastal sea area with artificial induction of phytoplankton flora to diatom dominant communities.日本海風成循環流の季節変化に対する地形性ベータの影響
http://hdl.handle.net/2115/68160
Title: 日本海風成循環流の季節変化に対する地形性ベータの影響
Authors: 朝日, 啓二郎; 磯田, 豊
Abstract: A two-layer analytic solution and the two-layer numerical model driven by the wind stress are used to explain the observed seasonal variation of horizontal circulation in the Japan Sea. Special attention is given to the topographic β-effect on the generation of bottom-trapped wave and surface-trapped wave activities on the planetary β plane. The positive curl of wind stress in the northern Japan Sea, where the planetary β in the lower layer is locally canceled by the topographic β, was found to play an important role in the seasonal change of abyssal circulation.2017-12-27T15:00:00Z朝日, 啓二郎磯田, 豊A two-layer analytic solution and the two-layer numerical model driven by the wind stress are used to explain the observed seasonal variation of horizontal circulation in the Japan Sea. Special attention is given to the topographic β-effect on the generation of bottom-trapped wave and surface-trapped wave activities on the planetary β plane. The positive curl of wind stress in the northern Japan Sea, where the planetary β in the lower layer is locally canceled by the topographic β, was found to play an important role in the seasonal change of abyssal circulation.青森県むつ市沖から採集されたカグラザメ Hexanchus griseus
http://hdl.handle.net/2115/68159
Title: 青森県むつ市沖から採集されたカグラザメ Hexanchus griseus
Authors: 河合, 俊郎; 木村, 克也; 川畑, 達; 神, 正人
Abstract: A single male specimen of a bluntnose sixgill shark, Hexanchus griseus(Bonnaterre, 1788), was collected from the western North Pacific, off Aomori Prefecture, northern Japan in January 2015. This is the first record of this species from Aomori Prefecture, and the northern-most record of this species around Japanese waters.2017-12-27T15:00:00Z河合, 俊郎木村, 克也川畑, 達神, 正人A single male specimen of a bluntnose sixgill shark, Hexanchus griseus(Bonnaterre, 1788), was collected from the western North Pacific, off Aomori Prefecture, northern Japan in January 2015. This is the first record of this species from Aomori Prefecture, and the northern-most record of this species around Japanese waters.