本文根据 4 0年间收集的综合观测资料、部分成果以及 1998/ 1999年本课题执行的 2个航次的调查和岸边监测 ,分析了渤海浮游植物生物量的年循环规律、水平分布的年际变化及长期变化。结合渤海水温、盐度、黄河径流量及营养盐浓度的变化 ,初步分析了原因。渤海为高生产力陆架海 ,每年有 2次生物量的高峰期 ,水华时间有 1个月的前后移动 ;生物量及其水平分布的年际变化大于 10年际变化。渤海温盐有增加趋势 ,无机氮浓度增加、磷酸盐浓度降低 ,河流输入变化只影响局部海域子系统 ,近岸海域的富营养化使得营养盐更多地消耗在近岸 ,而中央海区依然保持良好水质。物理系统的变化是该时空变化的重要原因之一。

The environment of the Bohai Sea has greatly changed in the past four decades. By integrating all data from our cruises and previous work, the possible long-term variations of phytoplankton biomass in the Bohai Sea are analyzed. The annual cycle of biomass and the interannual variation of its spatial distribution are summarized. The Bohai Sea is a highly productive shelf sea with two high-biomass periods each year. The time that bloom occurs has a one-month shift back and forth in different years and the interannual variation is larger than the decadal one. With the increasing of DIN and decreasing of DIP, the change of river loads has slight influence while the shift of the physical system (e.g. temperature, circulation, stratification/mixing) induced by climate change may greatly influence the evolution of the phytoplankton-nutrient system by redistributing them in the basin scale. The coastal eutrophication may consume more nutrients in the coastal area thus the central parts of the Bohai Sea maintain their good water quality. It is necessary to conduct long-term monitoring to further study the interannual and decadal variations of the system.