The seasonal abundance and vertical distribution of the <3-μm phytoplakton in the north basin of Lake Biwa
The seasonal abundance and vertical distribution of the <3-μm phytoplakton in the north basin of Lake Biwa
复制标题
琵琶湖北部流域<3μm浮游植物的季节丰度及垂直分布
DOI：
10.1007/bf02347022
复制
发表时间：
1986
影响因子：
2
通讯作者：
T. Nagata
中科院分区：
文献类型：
--
作者：
T. Nagata
1985 年 6 月至 12 月期间，在琵琶湖北部盆地的远洋地点研究了尺寸分级叶绿素浓度（<3 μm、3 至 25 μm 和 >25 μm）的季节变化。还使用异硫氰酸荧光素染色落射荧光显微镜技术检查了 <3 μm 级分中的自发荧光浮游生物细胞。与较大部分相比，<3μm 的浮游植物（通常以色球藻类蓝细菌为主，少数情况下以小型真核生物为主）表现出明显不同的季节变化模式。即从8月到9月初，较大组分的叶绿素含量下降幅度较大，而<3μm叶绿素含量下降不明显。此外，<3μm部分的蓝藻细胞密度在此期间显示出最大值（2–3.5×105cells·ml−1）。在此变化过程中，<3μm 叶绿素对总叶绿素的相对贡献从 <5% 增加到 45%。 7月下旬至8月，除了在15m深度出现较大的蓝藻(>4μm3)，而在0.5和10m深度没有出现较大的蓝藻(>4μm3)外，<3μm浮游植物的分布和组成没有明显的垂直趋势。这些大细胞也在十一月和十二月被发现。讨论了该流域浮游植物大小结构发生的剧烈季节性变化与放牧、养分消耗和下沉的关系。
The seasonal changes in the size-fractionated chlorophyllaconcentrations (<3 μm, 3 to 25 μm, and >25 μm) were investigated at a pelagic site of the north basin of Lake Biwa during June to December 1985. Autofluorescing plankton cells in the <3-μm fractions were also examined using the fluorescein isothiocyanate staining epifluorescence microscopic technique. The <3-μm phytoplankton (usually dominated by chroococcoid cyanobacteria except for a few cases dominated by small eukaryotes) showed a clearly different pattern of seasonal change compared with the larger fractions. That is, from August to early September, chlorophyllaof the larger fractions declined considerably, while the <3-μm chlorophylladid not decrease significantly. Moreover, cyanobacterial cell density in the <3-μm fraction showed a maximum value (2–3.5×105cells·ml−1) during this period. The relative contribution of the <3-μm chlorophyllato the total chlorophyllaincreased from <5% to 45% during the course of this change. No clear vertical trend in the distribution and composition of the <3-μm phytoplankton was found, except that relatively large cyanobacteria (>4 μm3) appeared at a depth of 15m but not at 0,5 and 10 m from late July to August. These large cells were also found in November and December. The drastic seasonal change of phytoplankton size structure occurring in this basin was discussed in relation to grazing, nutrient depletion and sinking.