夏冬两季大亚湾典型海域浮游植物粒级结构特征

Phytoplankton biomass size structure in Daya Bay during summer and winter

于2010年8月和2011年1月对大亚湾6个典型站位的浮游植物进行采样调查,估算了浮游植物细胞体积,分析了各区域浮游植物的粒级组成,比较了大亚湾各典型站位浮游植物生物量的粒级结构差异。大亚湾浮游植物的细胞体积范围为64—496757μm3,以1600—3200μm3粒级的浮游植物种类最多,分布在粒级谱两端的浮游植物的种类较少。夏季大亚湾浮游植物细胞丰度和由细胞体积转换的湿重生物量高于冬季,夏季平均为76.5×104个·L 1和1.6mg·L 1,冬季平均为22.52×104个·L 1和0.45mg·L 1。夏冬两季均以营养盐水平高且水交换能力差的S8站位生物量最高,且该站夏冬两季均以甲藻为主。夏季大亚湾湾内站位和冬季大部分站位顶端粒级的种类对浮游植物初级生产力和碳库的贡献很重要,但因为丰度小,在细胞丰度表示的浮游植物现存量和优势种中没有体现,细胞体积转换生物量则能更为客观合理地表征浮游植物现存量和作为优势种的判断依据。

Based on samples collected at six typical sites of Daya Bay in August 2010 and January of 2011, phytoplankton cell volume was estimated, phytoplankton size structure was analyzed, and phytoplankton biomass size structure was investigated. Cell volume of phytoplankton in Daya Bay was in the range of 64 to 496757 μm^3, though only a few species distributed at the two ends of the range; the species distributed in the range of 1600-3200 μm^3 were the richest. Phytoplankton cell abundance and cell volume converted biomass were 76.5×10^4 cell·L^-1 and 1.6 mg·L^-1 in summer, and 22.52×10^4 cell·L^-1 and 0.45 mg·L^-1 in winter, respectively, which were both obviously lower than those in summer. S8 that was labeled by highest nutrient and lowest water exchange capability showed the highest biomass and was dominated by dinoflagellates in both summer and winter. At most sites in winter and those sites inside the bay in summer, the species with the largest cell size made significant contribution to biomass and carbon stock. However, the contribution of large species with low abundance could not be seen through cell abundance represented biomass and key species. Biomass converted by cell volume was comparatively a more reasonable way to represent phytoplankton stock and to identify key species than cell abundance.