Evaluation of shellfish culture potential in coastal areas based on carrying capacity of waters

为实现近海水产养殖生物产品的可持续利用，对近海沃茨的承载力进行了研究。田间试验在日本东北部三陆海岸的大槌湾进行。浮游植物初级生产力的准确估计和氧动力学的理解是最重要的尺度承载能力。用于自然和活性荧光的生物光学传感器被证明是用于初级生产的快速和准确定量的有用方法。这是通过应用天然荧光技术和荧光脉冲幅度调制技术监测水产养殖场初级生产力的实例。在春季，养殖的裙带菜和浮游植物的生长作为营养竞争者进行了比较。次表层的供氧量也是决定水体承载力的重要因素。在夏季，贝类筏底沉积物的耗氧量很高，在3 ~ 5天内就可将溶解氧消耗殆尽。然而，没有形成缺氧水。风驱动的环流和内潮引起的近岸沃茨的流入提供了足够的溶解氧，以防止缺氧层的形成。

Evaluation of carrying capacity of coastal waters was investigated for sustainable exploitation of biological production from coastal aquaculture. Field experiments were conducted in Otsuchi Bay, a ria in Sanriku coast on the northeastern coast of Japan. Accurate estimation of phytoplankton primary production and understanding of oxygen dynamics are of prime importance for scaling the carrying capacity. Bio-optical sensors for natural and active fluorescence prove to be useful approaches for rapid and accurate quantification of primary production. This was exemplified by field application of both the natural fluorescence technique and the pulse amplitude modulation of fluorescence to monitor primary production in aquaculture ground. Growth of the cultured kelp called wakame and phytoplankton was compared as competitors for nutrients during spring. As another important factor determining the carrying capacity, oxygen supply of subsurface layers is considered. During summer time, oxygen consumption of bottom sediment under shellfish rafts was high enough to exhaust dissolved oxygen within three to five days. However, no anoxic water was formed. Wind-driven circulation and inflow of subsurface coastal waters induced by the internal tide supplied enough dissolved oxygen to prevent the formation of anoxic layer.