Planktonic microbes: Tiny cells at the base of the ocean's food webs

College of Oceanography, Oregon State University, Corvallis, OR 97331, USA.
Trends in Ecology & Evolution (Impact Factor: 16.2). 02/1991; 6(2):50-4. DOI: 10.1016/0169-5347(91)90122-E
Source: PubMed

ABSTRACT Phytoplankton in the size range 5-100 μm was originally thought to be the primary source of food for most life in the sea. However, smaller planktonic microbes, down to 0.2 μm in size, have been the focus of intensive investigation by marine scientists during the past two decades. These microbes attain high abundance and biomass in all parts of the world ocean. They include non-photosynthesizing bacteria, at least two types of photosynthesizing prokaryotes, and eukaryotic phototrophs. The new information has resulted in a greatly revised concept of how pelagic ecosystems in both marine and freshwater environments function. The original idea of a basically linear food chain from diatoms to copepods to fish has given way to an extremely complex model of trophic interactions within a microbial food web, which supports metazoan food webs via biomass production of both heterotrophic and autotrophic cells.

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    Environmental Research Letters 11/2010; 5(4):045301. DOI:10.1088/1748-9326/5/4/045301 · 3.91 Impact Factor
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    • "This level also matches a previous mortality estimate of bacterioplankton caused by protozooplankton in the Bothnian Sea area (Wikner & Hagström 1991) b Bacterial diet was assumed to be DOC c Wikner & Hagström (1988, 1991) have estimated that 90% of the carbon demand by bactivorous flagellates (1–5 µm) consist of picoplankton (similarly: Kuuppo-Leinikki 1990, Sherr & Sherr 1991). It was assumed that 70% of this constituted bacteria and 20% cyanobacteria (Hagström et al. 1988) d Prey size spectrum based on results from Rassoulzadegan & Sheldon (1986), Wikner & Hagström (1988), Sherr & Sherr (1991) and Dolan & Gallegos (1991) e Prey size spectrum based on results from Rassoulzadegan & Sheldon (1986), Wikner & Hagström (1988), Sherr & Sherr (1991) and Dolan & Gellegos (1991) f Prey size spectrum based on results from Fenchel (1980), Jonsson (1986), Rassoulzadegan et al. (1988), Verity & Villareal (1986) and Dolan & Gellegos (1991). These prey size spectra agree with findings in the Gulf of Finland (Kivi et al. 1996), where ciliates have strong regulating effects on prey <10 µm in presence of zooplankton g Following Kivi et al. (1996), besides large phytoplankton >10 µm, microzooplankton (e.g. "
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