Impacts of nutrients and zooplankton on the microbial food web of an ultra-oligotrophic lake
Impacts of nutrients and zooplankton on the microbial food web of an ultra-oligotrophic lake
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DOI：
10.1093/plankt/20.8.1501
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发表时间：
1998-08-01
影响因子：
2.1
通讯作者：
Schallenberg, M
中科院分区：
文献类型：
--
作者：
Burns, CW;Schallenberg, M
在极端贫营养的湖泊和海洋中，哲水蚤桡足类是占主导地位的中型浮游动物和枝角类一般稀疏或缺席。为了确定捕食和营养物富集对超贫营养湖泊的浮游微生物食物网的影响，我们在低生物量（3 μ m和异养细菌分别增加了50%和15%，超过4天，但那些蓝藻picoplancoma下降了68%）的桡足类和枝角类。在环境密度（1和4 l（-1））的哲水蚤桡足类（Boeckella dilarata）的存在下，迅速和严重抑制纤毛虫种群增长超过4天，也降低了鞭毛虫>3 μ m，即使微生物的生长是通过添加营养素增强。一个小的枝藻，Ceriodaphnia dubia，在两倍的密度，但类似的生物量，桡足类的存在下，抑制纤毛虫和鞭毛虫的净增长率在较小的程度。4天后异养细菌的净增长率下降与鞭毛虫丰度，与鞭毛虫调节的可能性一致。虽然细菌和藻类增加营养施肥（自下而上的控制），捕食（自上而下的控制）似乎发挥了重要的作用，在结构的微生物食物网，这个超贫营养湖泊在夏季。
In ultra-oligotrophic lakes and the sea, calanoid copepods are the dominant mesozooplankton and cladocerans are generally sparse or absent. To determine the effects of predation and nutrient enrichment on the pelagic microbial food web of an ultra-oligotrophic lake, we added copepods and cladocerans at low biomasses (3 mu m and heterotrophic bacteria increased by 50 and 15%, respectively, over 4 days, but those of cyanobacterial picoplankton decreased by 68%. The presence of calanoid copepods (Boeckella dilarata) at ambient densities (1 and 4 l(-1)) rapidly and severely suppressed ciliate population growth over 4 days and also lowered that of flagellates >3 mu m, even when microbial growth was enhanced by added nutrients. The presence of a small cladoceran, Ceriodaphnia dubia, at double the densities, but similar biomasses, to those of copepods, depressed the net growth rates of ciliates and flagellates to a lesser degree. The net growth rate of heterotrophic bacteria after 4 days declined with flagellate abundance, consistent with the possibility of regulation by flagellates. Although bacteria and algae increased in response to nutrient fertilization (bottom-up control), predation (top-down control) appeared to play an important role in structuring the microbial food web of this ultra-oligotrophic lake in summer.