Seasonal studies on the relative importance of different size fractions of phytoplankton in Narragansett Bay (USA)
Seasonal studies on the relative importance of different size fractions of phytoplankton in Narragansett Bay (USA)
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纳拉甘西特湾（美国）浮游植物不同大小部分相对重要性的季节性研究
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发表时间：
1975
期刊：
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通讯作者：
T. Smayda
中科院分区：
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作者：
E. Durbin;R. Krawiec;T. Smayda
从1972年11月至1973年10月，以年为周期，对纳拉甘塞特湾下游（美国）4种不同粒级（<20，20 ~ 60，60 ~ 100，>100 μm）浮游植物的组成和生产力进行了跟踪研究。硅藻占主导地位的人口在冬季和春季开花，在秋季，夏季人口占主导地位的鞭毛虫。微型浮游生物（<20 μm）是最重要的，占全年叶绿素a生物量的46.6%，占总生产量的50.8%。不同组分的相对重要性表现出明显的季节性。在冬春季和秋季水华期间，网采浮游生物组分（>20 μm）是最重要的。矮脚鹬在夏天占统治地位。不同组分的年平均同化数差异不显著。然而，在冬春水华期间，净浮游生物的同化数显著高于微型浮游生物部分。温度占大部分的同化数的变化，一个显着的营养胁迫观察到只有两次。从14 C吸收和三磷酸腺苷（ATP）-细胞碳计算的生长速率通常相当高;在夏季鞭毛虫和秋季中肋骨条藻开花期间，最大值为每天1.90倍。观察到的优势物种变化的一系列短周期与种群生理状态的变化有关。在浮游植物丰度达到高峰时，一般观察到较高的增长率，而在这些高峰之间观察到较低的增长率。高的生长率和同化数通常发现，在较低的纳拉甘塞特湾浮游植物一般没有营养限制1972年11月至1973年10月。因此，在这个浅河口的营养再生，必须非常迅速时，原位营养水平低。
The composition and productivity of four different size-fractions (<20, 20 to 60, 60 to 100, >100 μm) of the phytoplankton of lower Narragansett Bay (USA) were followed over an annual cycle from November, 1972 to October, 1973. Diatoms dominated the population in the winter-spring bloom and in the fall, the summer population was dominated by flagellates. The nannoplankton (<20 μm) were the most important, accounting for 46.6% of the annual biomass as chlorophyll a and 50.8% of the total production. The relative importance of the different fractions showed a marked seasonality. During the winter-spring and fall blooms the netplankton fractions (>20 μm) were the most important. Nannoplankters domnated in the summer. The yearly mean assimilation numbers for the different fractions were not signfficantly different. During the winter-spring bloom, however, the assimilation numbers for the netplankters were significantly higher than those for the nannoplankton fraction. Temperature accounted for most of the variability in assimilation numbers; a marked nutrient stress was observed on only two occasions. Growth rates calculated from 14C uptake and adenosine triphosphate (ATP)-cell carbon were generally quite high; maxima were >1.90 doublings per day during blooms of a flagellate in the summer and of Skeletonema costatum in the fall. The series of short cycles observed in which the dominant species changed were related to changes in the physiological state of the population. Higher growth rates were generally observed at times of peak phytoplankton abundance while lower growth rates were observed between these peaks. The high growth rates and assimilation numbers usually found suggest that the phytoplankton in lower Narragansett Bay was not generally nutrient-limited between November, 1972 and October, 1973. Nutrient regeneration in this shallow estuary, therefore, must be very rapid when in situ nutrient levels are low.