Rassoulzadegan, F. Université Paris VI (UPMC), CNRS-SDU/INSU, Lab. Océanographie Biologique, ESA 7076, (+33) 4 93 76 38 34
Thingstad, T. University of Bergen, Department of Microbiology, frede.thingstad@imp.uib.no
Wassmann, P. Norwegian College of Fishery Science, University of Tromsø, paulw@nfh.uit.no

 
CAN DOMINANT STRUCTURE OF THE FOOD WEB EXPLAIN THE VARIABILITY OF THE VERTICAL FLUX?
 
The physical environment determines nutrient availability and the light regime and hence particles potentially available for export to depth. Traditionally emphasis has been given to grazing food chain and new production, all essential for the exploitation of marine pelagic resources. The concept of the microbial loop extended our idea of pelagic food web configuration by incoporating nutrient recycling/availability, recycling and DOC. Pelagic systems are potentially capable of retaining and recycling all autochthonous organic material, although some losses due to sinking particles inevitably occur. The apprearance of integrated pelagic food web models, involving competitive, commensal and predatory mechanisms as well as phytoplankton, bacteria, cilliates and a variety of zooplankton feeding types, results in an interpretation where the vertical export of biogenic matter not only depends on bottom-up regulation as determined by physical forcing, but to a large extent on the structure and function of the prevailing planktonic food web. Simple models of nutrient availability, meterological forcing and radiation may give rise to reliable estimates of primary production, but a non-consideration of the dynamics of pelagic food web structure and in particular the joint regulation by resource availability and predation prevents an adequate understanding, let alone prediction, of the vertical biogenic export.
 
Day: Thursday, Feb. 4
Time: 12:15 - 12:30pm
Location: Sweeney Center
 
Code: SS39TH1215S