Dynamics of primary productivity in a subarctic coastal area affected by a large river discharge.

受大河流流量影响的亚北极沿海地区初级生产力动态。

• 批准号: 15310019
• 负责人: KUDO Isao
• 金额: $ 8.77万
• 依托单位: HOKKAIDO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-15310019/
• 关键词: river-coastal ocean system; nutrients; primary production; phytoplankton; heterotrophic bacteria; Tokachi river; iron; bio-element cycle; 石狩川; ウイルス; 炭素循環

Chemical substances and biochemical parameters were measured in the subarctic coastal region which receives fresh water and nutrients from the Tokachi River, one of the largest river in Japan. River discharge increased ten times after April due to a spring thaw and continued until June. In the coastal region, nutrients were depleted after a spring bloom which occurred in April. River plume area showed an elevated concentration of nutrients and iron originated from the Tokachi River. High concentration of chlorophyll a was observed only in the river plume because outside the plume nutrients were depleted. The mainstream of the Tokachi River and its tributaries showed different concentration of nutrients. This may be attributed to the different type of land use, i.e., farming, dairy farming, forest and city sewage plants. We also investigated the heterotrophic microbial process (microbial loop) which is related to the fate of organic carbon produced by phytoplankton. The abundance of heterotrophic bacteria was higher in the river plume than off shore region. Dissolved organic carbon was also higher in the plume. Riverine organic matter may accelerate the growth of heterotrophic bacteria in the plume. The mortality of bacteria was investigated by a dilution culture experiment. Virus infection was accounted for more than 80% of the mortality. The regenerated organic carbon may contribute to the further bacterial production.

在亚北极沿海地区测量了化学物质和生化参数，该地区从日本最大的河流之一十胜河接收淡水和养分。由于春季解冻，河流流量在四月份之后增加了十倍，一直持续到六月份。在沿海地区，四月春花过后，养分耗尽。河流羽流区域显示源自十胜河的营养物和铁浓度升高。仅在河流羽流中观察到高浓度的叶绿素 a，因为羽流外部的营养物质已耗尽。十胜川干流及其支流的营养盐浓度存在差异。这可能归因于不同类型的土地利用，即农业、奶牛养殖、森林和城市污水处理厂。我们还研究了与浮游植物产生的有机碳的命运相关的异养微生物过程（微生物循环）。河流羽流中异养细菌的丰度高于近海地区。羽流中溶解的有机碳也较高。河流有机物可能会加速羽流中异养细菌的生长。通过稀释培养实验研究细菌的死亡率。病毒感染占死亡人数的80%以上。再生的有机碳可能有助于细菌的进一步生产。

项目成果

Distribution and sources of organic matter in surficial sediments on the shelf and slope off Tokachi, western North Pacific, inferred from C and N stable isotopes and C/N ratios

• DOI: 10.1016/j.marchem.2005.10.002
• 发表时间: 2006-02
• 期刊: Marine Chemistry
• 影响因子: 3
• 作者: T. Usui;S. Nagao;Masanobu Yamamoto;Koji Suzuki;I. Kudo;S. Montani;A. Noda;M. Minagawa

Distribution and sources of organic matter in surficlal sediment on the shelf and slope off Tokachi, western North Pacific, inferred from C and N stable isotopes and C/N ratio s

根据C、N稳定同位素和C/N比推断北太平洋西部十胜陆架和斜坡表面沉积物中有机质的分布和来源

• 发表时间: 2006
• 期刊: Marine Chemistry 98
• 作者: Usui et al.