Interaction between natural planktonic ecosystem and cultured animals in the coastal aquaculture environment.

本研究的目的是评估养殖和河流排放可能对环境造成的影响。本文于1996年和2000年进行了大量的数据收集和观测，确定了典型的珍珠贝和牡蛎养殖场——阿古湾和马托亚湾的物理和化学参数变化及其对天然浮游生物生态系统的影响。在阿古湾，夏季海底沉积物持续提供营养物。叶绿素a分异测量和显微观测结果表明，微浮游生物和纳米浮游生物是全年碳生物量的主要组成部分。计算出的从微型浮游生物（包括细菌）到微型浮游生物的潜在碳流量表明，有机物质的通道主要是通过微生物食物网驱动的，例如微型浮游生物-异养纳米鞭毛虫-微型浮游动物，等等。微生物食物链对中浮游动物生物量也有影响。在松谷湾，以叶绿素a为基础的浮游植物生物量在夏季和秋季有所增加。NO_3-N主要由入流河流供给，夏季和秋季海湾NO_3-N浓度增加。PO_4-P和NO_2-N主要通过内湾底部的再生供给，PO_4-P的活跃再生发生在夏季和秋季。海湾SiO_2-Si的主要来源是入流河流，但夏季和秋季也受到内部海湾底部更新的影响。红场比和半饱和常数表明，在夏季和秋季河流流量较大时，浮游植物生物量通常受氮的限制，偶尔受磷的限制。因此，夏季和秋季浮游植物生物量的增加是由入流河流的氮负荷和内湾底部PO_4-P的主动更新引起的。少

The aim of the present study is to assess the possible environmental impact caused by culture farming and river discharge. Intensive data collection and observations were carried out during 1996 and 2000 to determined the variations of physical and chemical parameters and their impacts on the natural plankton ecosystem in Ago Bay and Matoya Bay, which are both typical embayments with pearl oyster and/or oyster culture grounds, respectively.In Ago Bay, nutrients were continuously supplied from the bottom sediment during summer. The size-fractionated chlorophyll a measurements and the microscopic observations revealed that the picoplankton and nanoplankton were major components in term of carbon biomass throughout the year. The calculated potential carbon flow from pico-sized plankton including bacteria to micro-sized plankton indicate that the conduit for organic materials is driven inainly through the microbial food web, e.g. picoplankton-heterotrophic nanoflagellates-microzooplankton, … More througout the year. It is also suggested that the microbial food chain affect the mesozooplankton biomass.In Matoya Bay, the phytoplankton biomass based on chlorophyll a increased in summer and autumn. NO_3-N was mainly supplied from the inflow rivers and the concentration increased in summer and autumn in the bay. PO_4-P and NO_2-N were mainly supplied through regeneration from the bottom at the interior bay, and the active regeneration of PO_4-P occurred in summer and autumn. The main source of SiO_2-Si in the bay was the inflow rivers, but it also influenced by regeneration from the bottom at the interior bay in summer and autumn. Redfield-ratio and half saturation constants were indicated that phytoplankton biomass in the bay was usually limited by nitrogen, and occasionally, by phosphorus when river flow was higher in summer and autumn. Therefore, it was suggested that loading nitrogen from the inflow rivers and active regeneration of PO_4-P from the bottom at the interior bay triggered the increase of phytoplankton biomass in summer and autumn. Less