Role of microbes in pelagic food webs: A revised concept

Sherr, Evelyn B.; Sherr, Barry F.

doi:10.4319/lo.1988.33.5.1225

Cited by 447 publications

(238 citation statements)

References 13 publications

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“…Picophytoplanktons are particularly likely to be an important prey. Although the microbial loop tends to be pictured as a material flow starting from bacteria and archaea that are fed on POM or dissolved organic matter (i.e., protistan bacterivory), nano-and microplanktonic protists should also play primary roles in the picophytoplanktonbased microbial loop (37,40,41) that, hence, makes substantial contributions to the flow of carbon and energy in aquatic environments (42). Additional studies of cPPB-aE, including its suitability as a proxy for protistan herbivory, may provide approaches for quantifying the contribution of picophytoplankton to flux in the aquatic geochemical cycle.…”

Section: Resultsmentioning

confidence: 99%

Ubiquity and quantitative significance of detoxification catabolism of chlorophyll associated with protistan herbivory

Kashiyama

Yokoyama²,

Kinoshita

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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Chlorophylls are essential components of the photosynthetic apparati that sustain all of the life forms that ultimately depend on solar energy. However, a drawback of the extraordinary photosensitizing efficiency of certain chlorophyll species is their ability to generate harmful singlet oxygen. Recent studies have clarified the catabolic processes involved in the detoxification of chlorophylls in land plants, but little is understood about these strategies in aquatic ecosystem. Here, we report that a variety of heterotrophic protists accumulate the chlorophyll a catabolite 13 2 ,17 3 -cyclopheophorbide a enol (cPPB-aE) after their ingestion of algae. This chlorophyll derivative is nonfluorescent in solution, and its inability to generate singlet oxygen in vitro qualifies it as a detoxified catabolite of chlorophyll a. Using a modified analytical method, we show that cPPBaE is ubiquitous in aquatic environments, and it is often the major chlorophyll a derivative. Our findings suggest that cPPB-aE metabolism is one of the most important, widely distributed processes in aquatic ecosystems. Therefore, the herbivorous protists that convert chlorophyll a to cPPB-aE are suggested to play more significant roles in the modern oceanic carbon flux than was previously recognized, critically linking microscopic primary producers to the macroscopic food web and carbon sequestration in the ocean. phototoxicity of chlorophylls | microbial herbivory | phagocytosis | biodiversity of eukaryotes | microbial loop C hlorophylls are crucial to sustaining most life forms on Earth, the majority of which ultimately depend on solar energy. Photoexcitation of chlorophylls initiates various photosynthetic reactions that convert the energy of photons into chemical potentials, which in turn, drive the full range of metabolic reactions throughout the global ecosystem. Chlorophylls play a central role in the photosynthetic apparatus by absorbing light and transferring the excitation energy to the reaction centers of photosystems before photosynthetic electron transport. However, without measures to contain the excited energy, chlorophylls can harm organisms because of their high photosensitizing potential.

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Section: Resultsmentioning

confidence: 99%

Ubiquity and quantitative significance of detoxification catabolism of chlorophyll associated with protistan herbivory

Kashiyama

Yokoyama²,

Kinoshita

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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“…The intricate and ever changing structure of the pelagic foodweb deserves considerable attention (e.g. FASHAM, 1984;HEWES, HOLM-HANSEN and SAKSHAUG, 1985;SHERR and SHERR, 1988;BJO/RNSEN and KUPARINEN, 1991 a,b;LANCELOT, BILLEN, VETH, BECQUEVORT and MATHOT, 1991) and is currently the subject of intense investigation, in projects ranging from detailed study by an individual scientist to large international programmes like the Joint Global Ocean Flux Study (DE BAAR, FRANSZ, GANSSEN, GIESKES, MOOK and STEL, 1989;DUCKLOW and HARRIS, 1993). In reality there is a multiplicity of cycles and interactions, where several organisms are also capable of operating various trophic functions at once.…”

Section: Concepts Of Phytoplanlcton Growth and Biomassmentioning

confidence: 99%

von Liebig's law of the minimum and plankton ecology (1899–1991)

Baar

1994

Progress in Oceanography

237

132

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-The Law of the Minimum was originally formulated by Justus yon Liebig, as one of the 50 interlinked laws concerned with agriculture. The original writings ofJ. von Liebig often were misinterpreted by his successors. BRAt, rOT (1899) took this one law out of its context and proposed that limitation by nitrogen is a dominant factor in plankton ecology, far beyond its original application to agriculture. This was opposed by NAmANSOrn~ (1908) who suggested instead a dynamic balance of growth and loss terms. Towards validating, or eventually falsifying Brandt's hypothesis, Atkins, Harvey, Cooper and others developed the chemical methods necessary for re-defining ocean nutrient cycling and growth limitation. The major exception to these modem perspectives was the Antarctic Paradox of higla nutrients and low chlorophyll which inspired Gran, Atkins, Harvey and Cooper to pioneer the concept of iron limitation. An exhaustive overview is given of efforts to define Fe in seawater and its controlling effect on in situ plankton growth, for the 1920-1984 period. Somewhat parallel work in the laboratory on single species of algae in chelation-controlled mediahas provided much insight, but is sketched only briefly. Martin and contemporaries developed the chemical methods necessary for defming the ocean chemistry of Fe and its role for in situ growth. These developments are sketched for the 1982-1991 period. Once again the Law of the Minimum and associated bold hypotheses served, albeit briefly, to bring a nutrient element in the forefront of research. This, and the recent awareness of CO 2 as rate limiting factor, underline the conclusion that advances in sciences often hinge on advances in technology, confirming Kta-~ (1962). In this case the new analytical techniques developed by Atkins, Harvey, Cooper, Martin and their associates have proven revolutionary for plankton ecology. Some observations in plankton ecology may be reminiscent of the agricultural Law of the Minimum, but this would not warrant its direct application, beyond its original context and agriculture, to plankton ecology. Rather the net rate of increase ofphytoplankton is the dynamic balance of multiple growth and loss terms, together also determining the biomass at given time and space. 347

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“…A better knowledge of the carbon content of aquatic bacteria would constitute a decisive link between studies on bacterial production and on interactions between bacteria, autotrophs, and grazers (Bird and Kalff 1987;Scavia 1988). In both cases the size-dependent distribution of bacterial numbers, biovolume, and carbon (and nutrients) is of crucial interest for understanding microbial food webs (Sherr and Sherr 1988).…”

mentioning

confidence: 99%

From image analysis to chemical analysis of bacteria: A long-term study?

Psenner¹

1990

Limnol. Oceanogr.

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Role of microbes in pelagic food webs: A revised concept

Cited by 447 publications

References 13 publications

Ubiquity and quantitative significance of detoxification catabolism of chlorophyll associated with protistan herbivory

Ubiquity and quantitative significance of detoxification catabolism of chlorophyll associated with protistan herbivory

von Liebig's law of the minimum and plankton ecology (1899–1991)

From image analysis to chemical analysis of bacteria: A long-term study?

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