微型食物网

Summary
微型食物网的基本结构
以个体大小为依据的粒径谱为原则，划分为3个基本层次： （1）微微型浮游生物（0.2~2um）：除了异养细菌 异养细菌外，还包 异养细菌 括蓝细菌、原绿球藻 蓝细菌、 微微型自养生物，如绿藻 蓝细菌 原绿球藻以及其他一些微微型自养生物 微微型自养生物 类、金藻类、隐藻类、硅藻类中的一些种类。 （2）微型浮游动物（2~20um）：鞭毛虫 肉足虫和纤毛虫 鞭毛虫、肉足虫和纤毛虫 鞭毛虫 等原生动物。 （3）小型浮游动物（20~200um）：个体较大的原生动物纤 毛虫、后生动物轮虫以及富有甲壳动物的幼体和其他无脊椎 动物的幼体。
Literature
low-productive waters： bacteria are more important nutrient-rich waters ：phytoplankton are dominant
low：in oligotrophic and strongly eutrophied waters FWE high：in moderately nutrient-rich systems
2002).
In eutrophic systems: the lower food web efficiency is explained by increased abundances of inedible or toxic algae. Predation defense mechanisms or dominance of disfavored prey items are quite common in such aquatic environments (Havens et al. 2000; Persson et al. 2001).
Introduction
Heterotrophic bacteria
Prochlorococcus
Protozoa
cyanobacteria
Protozoa
Literature
Efficiency of a phytoplankton-based and a bacteria-based food web in a pelagic marine system
The food web efficiency in two contrasting food webs, one phytoplankton based and one bacteria based, was studied in a mesocosm（中型实验生态系） experiment using seawater from the northern Baltic Sea. Organisms included in the experiment were bacteria， phytoplankton, protozoa, and mesozooplankton(copepods).
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Treatment in different conditions： ： phytoplankton- based: NP at a high light level Phytoplankton were dominant producers (74%). bacteria-based : CNP a lower light level Bacteria dominated the productivity (91%),
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The results were supported by stable isotope analysis of mesozooplankton. We propose that climate change, with increased precipitation and river runoff in the Baltic Sea, might favor a bacteria-based food web and thereby reduce productivity at higher trophic levels. Owing to smaller sizes of the resources and predators in bacteria-based food webs, these generally have more trophic levels .Larger carbon losses can be expected in bacteria-based food webs, since about 70% of the ingested carbon is lost at each trophic level because of respiration and sloppy feeding(In addition, the increased freshwater transport and mixing with the surface water will probably cause a deepening of the halocline, which in turn will cause a poorer light climate for the phytoplankton. The combined effect of increased ADOC and freshwater transport would thus give bacteria a competitive advantage over phytoplankton
Introduction
过去认为的食物链基本模式： 网采浮游植物 20世纪80年代以来： PPOM（初级生产产生的颗粒有机物） PDOM（初级生产产生的溶解态有机物） DOM（海水溶解有机物）
不同的有机态物质被细菌吸收并形成细菌本身生物量的增长，这个过 程被称为细菌的二次生产。 细菌利用
桡足类
鱼类
Reason：1–2 extra trophic levels in the bacteria-based food web where carbon passed through flagellates and ciliates before reaching mesozooplankton, while in the phytoplanktonbased food web there was a direct pathway from phytoplankton to mesozooplankton.
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The food web efficiency, defined as mesozooplankton productivity per basal productivity (phytoplankton + bacteria), was 22% in the phytoplankton-based food web and 2% in the bacteria-based food web.
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Methodolagy:
☆Labeling the basal resources with radioactive DOC and
DIC . ☆ measuring productivity rates ☆ analyses of stable isotope ratios of nitrogen and carbon in mesozooplankton
an increase in ADOC and nutrient input to marine
Thus, increased input of organic matter to pelagic systems may result in a shift toward a bacteria-based system.
Literature
In oligotrophic oceanic systems : picoplankton (2–3 mm) are too small to be effectively ingested by mesozooplankton .Heterotrophic nanoflagellates or small ciliates may therefore constitute an additional trophic link in oligotrophic systems (Caron et al.1999; Sherr and Sherr
Introduction
微型生物食物环（ 微型生物食物环（网）：
异养细菌 原生动物 经二次生产形成的） （经二次生产形成的） 微微型植物 后生动物 小型） （小型） 。。。。
实际应用中微型食物网用来表示海洋生态系统中小于200um 的生物之间的关系。 其中，在微型食物网中，异养细菌在有机碳的转换过程中起 关键的作用。
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The bacterial productivity in the northern Baltic Sea is to a large extent based on ADOC (Sandberg et al. 2004). global warming increased precipitation
elucidate differences in food web
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(A) Bacterial and (B) primary productivity, and (C) oxygen consumption in the NP and CNP treatments.
(A) Dissolved inorganic phosphorus (DIP), (B)dissolved inorganic nitrogen (DIN), and (C) dissolved inorganic carbon (DOC) concentrations in the NP and CNP