1. General Model Information

Name: A (Bioenergetic Population) Foodweb Model for Study of Ecotoxicological Effects

Acronym: ECOTOX


Main medium: all
Main subject: (eco)toxicology, population dynamics
Organization level: Ecosystem, Population
Type of model: ordinary differential equations
Main application: research, decision support/expert system
Keywords: population, bioenergetic, carbon, toxicology, foodweb, foodchain, risk assessment

Contact:

L.J. (Sam) Bledsoe

Civil $ Environmental Engineering, Univ. California - Davis, Davis CA 95616, USA
phone: 530-752-5634
fax: 530-752-7872
email: sbledsoe@ucdavis.edu

Author(s):

L.J. (Sam) Bledsoe & Julie Yamamoto

Abstract:

(Report on Ecotox, Ver. 1.0, available from author) An integro-differential equation model simulates the dynamics of the energetics (weight, as carbon content) and age structure of species populations. Species are linked in a food web using functional response curves. Population dynamics are based on fecundity linked to food availability and mortality linked to predator-prey relations and energy status (i.e. starvation). The food web is driven by either static or dynamic plant resources which may be contaminated with multiple chemical (toxic) substances. Body burden of contaminants is traced through the food web populations and the processes of dietary, dermal and respiratory exposure, direct mortality (due to acute and/or chronic exposure), and reduction in foraging and reproductive rates are simulated. Effects of multiple toxicants are linearly additive by default and non-linear interactions may be simulated by addition of appropriate mechanisms. A five node foodweb (grasshopper, caterpillar, deer mouse, sparrow, kestrel, driven by alfalfa and walnut c rops) is simulated in a hypothetical example with various levels of dicofol and diazinon treatment as a demonstration, calibration and model test procedure. The results describe predicted effects of specific toxicant levels as they propagate through the populations of the food web and demonstrate critical parameter values for achievement of realistic dynamics. A risk assessment scenario with end point "maximum kestrel population mortality 10%" is described.


II. Technical Information

II.1 Executables:

Operating System(s): DOS or Windows NT/95 (link under construction 5/4/98, contact author by email for a diskette)

II.2 Source-code:

Programming Language(s): (link under construction 5/4/98, contact author by email for a diskette) Fortran 77 with Microsoft extensions contact author

II.3 Manuals:

contact author (User & reference available, see abstract) (under construction 5/4/98, contact author by email)

II.4 Data:

(under construction 5/4/98, contact author by email) (sample available with executable diskette)

III. Mathematical Information


III.1 Mathematics

Bledsoe, L.J. and B.A. Megrey. 1989. Chaos and Pseudoperiodicity in the Dynamics of a Bioenergetic food Web Model. American Fisheries Society Symposium 6:121-137.


III.2 Quantities

State:Animal weights (gC) by age, speciesAnimal population densities (/unit area) by age, speciesAnimal body burden of multiple chemicalsRate:energetics: ingestion, respiration, reproductionpop. dyn: birth, mortality, (e/im-igration as driver)toxicology: uptake (ingestion & dermal/respiratory), loss (transformation, excretion), direct mortality (adults or offspring), foraging depression, reproductive depression


III.2.1 Input

Parameters (typ. 1 or 2) for each process listed under rate variablesInitial population structureToxicant application schedule & lability parameters

III.2.2 Output

State and most rate variables as time series at specified intervals,Plots as separate function with alternate output file


IV. References

Bledsoe, L.J. and B.A. Megrey. 1989. Chaos and Pseudoperiodicity in the Dynamics of a Bioenergetic food Web Model. American Fisheries Society Symposium 6:121-137.

Bleddsoe, L.J. 1996. A foodweb model for study of ecotoxicological effects. (reference and user manual abstracted above)



V. Further information in the World-Wide-Web

(Home Page under construction 5/4/98)

VI. Additional remarks

Ver 1.0 of Ecotox is being revised pursuant to reviewer comments and will be available c. Fall 98.Further publication on Ecotox for the ecostoxicology literature are in process.
Sam Bledsoe, 5/4/98
Last review of this document by: L.J. (Sam) Bledsoe Mon May 4 19:48:11 1998
Status of the document: Contributed by L.J. (Sam) Bledsoe
last modified by Tobias Gabele Wed Aug 21 21:44:42 CEST 2002

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