Report of the

U.S. GLOBEC Georges Bank

Science Meeting

18 - 20 November 2003, Rhode Island


Cover Page




Presentation Abstracts

Poster Presentations

Appendix I: Agenda

Appendix II: List of Participants

Appendix III: List of Planned Publications

Inverse Modeling of the Food Web

Steele, J.H.1and A.R. Beet1
1Marine Policy Center, Woods Hole Oceanographic Institution, Woods Hole, MA 02543

Linear network analysis of food webs is often carried out by defining the links in the web and calculating the flux of energy, nutrients or biomass through the nodes. The problem is that we generally know more about the nodes than the links. To remedy this, a form of inverse modeling has been used where the links are the unknowns except for upper and lower bounds provided by available data. Because of the large number of unknowns relative to equations, a "global" constraint or objective function is required. Previous inverse models have minimized the sum of squares of the fluxes, but this does not have an obvious ecological basis. As an alternative we have applied the concept of resilience by calculating the network that maximizes the rate of return of the system after perturbation. We show that the structures determined for a pelagic microbial food web with these alternative objective functions can be quite distinct. We discuss the ecological implications and propose possible applications.

A powerpoint version and an html version of this presentation are available on-line.