NUTRITUNNEL

NUTRITUNNEL: “Nutrient tunnelling” and ”trophic bypass”; alternative food web routes from nutrients to zooplankton production

Project duration Feb 2008 – Feb 2011

Budget 3.9 mill NOK funded by Norwegian Research Council

Principal Investigator Prof. Frede Thingstad, University of Bergen, Norway

Project collaborators

  • Jens Chr. Nejstgaard (Unifob AS, Bergen, Norway)
  • Tom Andersen (University of Oslo)
  • Tsuneo Tanaka (Centre d’Oceanologie de Marseille, Marseille, France)
  • Vivi Pitta (HCMR, Crete)

Project description

The principal objective is to test the recent hypothesis that phosphate nutrient pulses in P-limited pelagic food webs may induce faster reproduction in zooplankton via mechanisms other than the classical phytoplankton biomass-increase.

Project summary

For more than a century, one of the fundamental challenges in marine sciences has been to understand the structure and function of pelagic food webs. During the last two decades, with recognition of the importance of microorganisms, much of this research has been directed toward understanding the linkage between microbial food webs and classical grazing food webs that lead to the production of fish and other large organisms. Recently, members of this consortium made an important new observation (published in SCIENCE), describing a possible new pathway by which nutrients may be transferred from microorganisms directly to copepods. In the published study (Eastern Mediterranean), we observed that following the addition of phosphorus, the supposed limiting nutrient, chlorophyll decreased while copepod egg production increased after at short delay.

To explain this unexpected result, two new hypotheses for the transport of the added P through the microbial food to secondary consumers without resulting in new alga biomass; “Nutrient Tunnelling” we propose to follow-up on these initial observations in a series of controlled laboratory based studies, and also a mesocosm study in the Eastern Mediterranean where the waters are ultra oligotrophic and P-tunnelling/bypass is likely to occur under natural conditions. The results of these studies, regardless of whether we verify of disprove the Nutrient Tunnelling and Bypass hypotheses, will contribute significantly to our understanding of the organization and function of marin food webs.