Effects of biological elements inflowing from agricultural ecosystems on coastal marine ecosystems

在北海道东部北海道Akkeshi湾Akkeshi-ko河口的Bekanbeushi河水系中，生物元素氮从陆地流入沿海海洋生态系统，特别是从整个流域的农业区流入畜牧业，影响沿海海洋生产，主要影响海草床的动态和马尼拉蛤和牡蛎的养殖生产，本文主要从以下几个方面进行了研究：利用GIS技术进行流域土地利用类型划分和制图。流域土地利用类型对水质的影响及其评价。三河口常态下出水量及营养盐浓度之比较量测。三河河口零星径流水量与营养盐浓度之比较量测。通过月测量和估算的Akkeshi-ko河口的水温、盐度、营养盐浓度和叶绿素浓度的分布 ...更多信息 Akkeshi-ko生态系统氮吸收模拟Akkeshi-ko河口沉积物的年龄测定和有机质沉积速率的估算。Akkeshi-ko河口海草氮吸收率的估算。河流水生植物氮吸收速率的估算。实验中估算蛤的碳收支。底栖和附生硅藻对蛤和牡蛎饵料的贡献及其评价。利用航空照片研究赤鹿湖河口海草床的历史动态。利用稳定同位素分析赤志湖生态系统的食物网通过数值模拟构建生态系统模型。根据他们的研究结果，Akkeshi-ko河口的高生产力是由陆地生态系统的最佳营养流入和稳定状态下海草床的高生产力支持的。虽然有大量的营养盐流入零星径流，这是澄清，这些足够的营养盐不能为沿海海水养殖。为了控制暴雨径流，并保证正常营养盐浓度的稳定供水，森林和湿地的存在是非常重要的。少

In a water system, River Bekanbeushi, the Akkeshi-ko estuary, Akkeshi Bay, of the eastern Hokkaido, that inflow of biological elements, nitrogen, from terrestrial area to coastal marine ecosystems, in particular from agricultural area for livestock farming in a whole watershed affects coastal marine production, mainly on dynamics of seagrass beds and mariculture production of the Manila clam and oysters, were studied from following aspects.Typological division and mapping of the watershed by land use type using GIS. Effects of types of land use in the watershed on water quality and their evaluation. Comparative measurements of outflow of water and nutrient concentrations in regular state at the three river-mouths. Comparative measurements of outflow of water and nutrient concentration in sporadic runoff at the three river-mouths. Distribution of water temperature, salinity, nutrient concentrations, and chlorophyll concentration in the Akkeshi-ko estuary by monthly measurements, and est … More imation of nitrogen uptake to Akkeshi-ko ecosystem. Age determination of sediments in the Akkeshi-ko estuary and estimation of sedimentation rate of organic matter. Estimation of nitrogen uptake rate by seagrasses in the Akkeshi-ko estuary. Estimation of nitrogen uptake rate by aquatic macrophytes in a river. Estimation of carbon budget in a clam in experiments. Contribution and its evaluation of benthic and epiphytic diatoms to diets of the clam and oysters. Historical dynamics of seagrass beds in the Akkeshi-ko estuary using aerial photographs. Food web analysis in Akkeshi-ko ecosystem by stable isotope. Construction of an ecosystem model by numerical simulation.In conclusion of their results, high production in the Akkeshi-ko estuary is supported by optimal nutrient inflow from terrestrial ecosystems and by high productiyitiy of seagrass beds in steady state. Although there are plenty of nutrients inflowed at sporadic runoff, it was clarifies that these sufficient nutrients can not contribute to coastal marine mariculture. For controlling on such a dashing runoff by heavy rain and for supply of water in steady state with normal nutrient concentration, it was suggested that the existence of forests and wetlands are very important. Less