, Volume 363, Issue 1–3, pp 59–72 | Cite as

A theoretical approach to structuring mechanisms in the pelagic food web

  • T. Frede Thingstad


In the literature there is a commonly used idealized concept of the foodweb structure in the pelagic photic zone food web, based to a large extenton size dependent relationships. An outline is here given of how theelementary size-related physical laws of diffusion and sinking, combinedwith the assumption of predators being size selective in their choice ofprey, give a theoretical foundation for this type of structure. It is shownhow such a theoretical fundament makes it possible to relate a broad specterof phenomena within one generic and consistent framework. Phenomena such asHutchinson‘s and Goldman‘s paradoxes, the influence of nutrients and watercolumn stability on the balance between microbial and classical food webs,bacterial carbon consumption, new production and export of DOC and POC tothe aphotic zone, eutrophication and diversity, can all be approached fromthis perspective. By including host-specific viruses, this approach gives ahierarchical structure to the control of diversity with nutrient contentcontrolling the maximum size of the photic zone community, size selectivityof predators regulating how the nutrient is distributed between size-groupsof osmotrophic and phagotrophic organisms, and viral host specificityregulating how the nutrients within a size group is distributed between hostgroups. I also briefly discuss how some biological strategies may besuccessful by not conforming to the normal rules of such a framework.Analyzing the behavior of these idealized systems is thus claimed tofacilitate our understanding of the behavior of complex natural food webs.


Phytoplankton Nutrient Content Mineral Nutrient Heterotrophic Bacterium Photic Zone 
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Copyright information

© Kluwer Academic Publishers 1998

Authors and Affiliations

  • T. Frede Thingstad
    • 1
  1. 1.Dept. of MicrobiologyUniversity of BergenBergenNorway

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