北黄海夏、冬季叶绿素和初级生产力的空间分布和季节变化特征

依据2006～2007年夏、冬两季的北黄海海洋综合调查资料,分析了叶绿素和初级生产力的空间分布和季节变化特征,并浅析了其主要影响因素.夏季北黄海Chl a的平均含量为30.75 mg·m-2(7.64～92.57 mg·m-2),冬季平均含量为18.72 mg·m-2(3.04～50.55 mg·m-2),与夏季相比显著偏低(P<0.05).夏季Chl a浓度的垂直分布呈现较为明显的分层现象,最大值基本出现在次表层;冬季大部分海域垂直分布均匀.夏季水柱初级生产力含量的平均值为471.2 mg·m-2·d-1(70.1～1 308.2 mg·m-2·d-1),其分布大致呈现近岸海域高、东部开阔海域较低的格局;冬季平均值为125.4 mg·m-2·d-1(72.6～245.5 mg·m-2·d-1),约为夏季的1/4,且分布较均匀.北黄海夏季磷酸盐可能成为限制浮游植物生长的因素,而冬季无机氮和磷酸盐可能同时成为限制因子.夏季和冬季的海表温度与表层Chl a浓度之间均呈负相关关系,R2分别为0.44(P=0.01,n=73)和0.41(P=0.01,n=71).

Spatial and Seasonal Variation of Chlorophyll and Primary Productivity in Summer and Winter in the Northern Yellow Sea

Chlorophyll and primary productivity were measured during two expeditions to the Northern Yellow Sea during the summer and winter of 2006/2007 in order to assess their spatial and seasonal variability as well as controlling factors. The average values of surface chlorophyll concentration were(0.779±0.640) mg·m-3 in summer and(0.652±0.508) mg·m-3 in winter. The chlorophyll content in water column in summer was(30.75±19.01) mg·m-2, whereas the value in winter(18.72±11.98) mg·m-2 showed a significant decrease(P<0.05). Due to intense water stratification in the summer, the maximum chlorophyll concentration that appears at the subsurface layer differs from the more uniformly mixed water column in winter. The primary productivity in water column in summer was 471.2 mg·m-2·d-1 on average, compared with only one-fourth of this value(125.4 mg·m-2·d-1) in winter. The horizontal distribution of primary productivity shows less variation in winter than in summer. While both nitrate and phosphate are likely to be the controlling factors of phytoplankton growth in winter, only phosphate can be considered as a controlling factor in summer. The sea surface temperature and chlorophyll concentration showed negative correlations both in summer and winter with R2 values of 0.44(P=0.01,n=73) and 0.41(P=0.01,n=71), respectively.