Group Leaders: Hugh Ducklow, Mike Roman, Ed Laws

Objectives:

Background:

Progress:

The Foodweb Working Group met several times to consider priority tasks in the SMP. Two themes emerged:

1. A need to analyze and synthesize findings from JGOFS fieldwork, and other pertinent studies, concerning regional and seasonal variations in foodweb structure. The Group agreed to begin assembling information of foodweb compartments and flows for formal analysis (see below).
2. A need to provide expert opinion and guidance concerning detailed representations of "minimum necessary complexity" foodweb structures and processes, to modelers. There is a wide range of opinion and belief about what level of detail is necessary in models of biogeochemical processes.  The FWWG seemed to agree that our task was to provide reasonably complete and detailed foodwebs, which could be simplified later to accommodate computational demands, etc.  Persons with interest or expertise (or both) were identified to provide guidance on formulating processes for particular model compartments (bacteria, phytoplankton, N-fixers, etc).

As a start, we resolved to begin collecting information on foodweb stocks and flows, for formal analysis.  Examples of foodweb analyses can be found in the references appended.

Information will be provided by volunteers with expertise in particular trophic groups and/or JGOFS study sites. The units of analysis will be integrated carbon and nitrogen stocks/fluxes in the euphotic zone (mmol C or N m^-2 [d^-1] ) for the following sites and time periods. We will set up a separate webpage in the future (via this web page) where files can be exchanged and accessed.

Sites and Times:

Data should be submitted in Excel files. Successive Excel sheets within a file could include: the "raw" data from discrete depths and dates from which integrals and averages were derived; the averaged integral quantities, etc. I will work with Joanie Kleypas and put an example up soon (e.g., Dick Dugdale's  model EQPAC files). The various references below provide suggested compartments and flows for analysis.
 

Food web group model development

The SMP food web group concluded that the model presented in Figure 1 was a good starting point from which to test the descriptive/predictive abilities of prognostic models relative to the goals of the SMP.  The first goal of the model development is to identify differential equations to describe the fluxes in the model.  These differential equations can then be incorporated into a one-dimensional physical model so that the behavior of the model can be examined in the regional test beds.
 

Tasks:
Group assignments are as follows:
 

Bacteria	Anderson, T; Ducklow	Nutrients	Carr; Deutsch; Falkowski; Follows; Gruber; Loukos
CaCO3	Kleypas	Physical models	Anderson, L; Chai; DeConto; Deutsch; Gruber; Najjar; Verschell
Data	Bates; Frost; Laws	Phytoplankton	Carr; Barber; DiTullio; Iglesias-Rodriguez; Laws; Lindsay; Lizotte; Loukas; Moore
Detritus, DOM	Anderson, L; Jackson; Najjar	Remineralization	Gruber; Bates; Carr; Deutsch; Falkowski; Gruber; Kleypas
Margins	Falkowski	Zooplankton	Frost; Roman

Membership:

Anderson, Laurence - WHOI
Anderson, Tom - Southampton
Barber, Richard - Duke
Bates, Nick - Bermuda
Carr, Mary-Elena - JPL/Pasadena
Chai, Fei - Maine
Dam, Hans - U. Connecticut
DeConto, Robert - Massachusetts/Amherst
Deutsch, Curtis - Princeton
DiTullio, Jack - Charleston
Ducklow, Hugh - VIMS
Falkowski, Paul - Rutgers
Follows, Mick - MIT
Frost, Bruce - Washington
Gruber, Niki - Princeton
Iglesias-Rodriguez, Debora - Rutgers
Jackson, George - Texas A&M
Kleypas, Joanie - NCAR/Boulder
Laws, Edward - Hawaii
Lindsay, Keith - NCAR/Boulder
Lizotte, Michael - Wisconsin/Oshkosh
Loukos, Harilaos - NOAA/Seattle
Moore, Keith - NCAR/Boulder
Najjar, R. - Pennsylvania State
Roman, Mike - Maryland
Verschell, Mark - NASA/Goddard

References:

Jackson GA, Eldridge PM. 1992. Food web analysis of a planktonic system of Southern California. Progr Oceanogr 30:223-51.

Ulanowicz, R.E. and T. Platt (ed.) 1985. Ecosystem theory for biological oceanography. Can. Bull. Fish. Aquat. Sci., 213: 260 p.

Ulanowicz, R.E., 1984, Community measures of food networks and their possible applications, pp 23-48 In: In M. Fasham (ed.), Flows of energy and materials in marine ecosystems: Theory and practice. Plenum Press.

Ulanowicz, R.E., 1986, Growth and development: Ecosystems Phenomenology, Springer-Verlag, New York.

Vezina, A. F. And T. Platt, 1987, Foodweb dynamics in the ocean. Part 1. Best- estimates of flow networks using inverse methods. Mar. Ecol Progr. Ser. 42:269-287.

Wulff, F., J. G. Field and K. H. Mann, 1989. (eds.) Network analysis in marine ecology,  Coastal and Estuarine Studies, Vol. 32, Springer-Verlag. (contains a seminal article by Ducklow, Fasham and Vezina).
 

Figure 1.