J. World Maricul. SOC. 15:355-366 (1984) A GENERAL MODEL OF THE AQUACULTURE POND ECOSYSTEM Faul H. Piedrahita,l David E. Brune,' George Tchobanoglous3 and Gerald T. Or10b3 ABSTRACT A computer model of a fertilized warm-water aquaculture pond has been developed. The model is intended t o represent the pond ecosystem and its response to external stimuli. The major physical, chemical, and biological processes and parameters are included in the model. A total of 22 state variables are used in the model (dissolved oxygen, ammonia, alkalinity, phytoplankton, zooplankton, fish, etc.). The model is fonnu- lated as a system of mass balance equations. The differential equations include stimulatory and inhibitory effects of environmental parameters on processes taking place in the pond. the entire growth period and diurnal as well as seasonal fluctuations may be i d e n t i f i e d . The equations may be solved for INTRODUCTION Warm water pond aquaculture remains, to zyxw a large extent, an empiri- cal activity. in the pond is necessary before optimum use of the resources can be real- ized. A mechanistic computer model of the pond ecosystem can serve as a tool for increasing our knowledge about the aquaculture pond. puter model, implemented i n an Apple I1 Plus computer using FORTRAN, can also be used as a research tool and as a teaching aid. A complete listing of the program may be obtained by writing the senior author; it is also available elsewhere (R. H. Piedrahita 1984, unpublished Ph.D. Dissertation, Univ. of California, Davis, zyxw CA 95616. Available from University Microfilms). A description of the general structure of the model has been presented previously (Piedrahita et al. 1983). zyxwvuts An improved understanding of the processes taking place The com- IDepartment of Agricultural Engineering, University of California, 'Department of Agricultural Engineering zyxwv , The Pennsylvania State Uni- 3Department of Civil Engineering, University of California, Davis , Davis, CA 95616. versity, University Park, PA 16802. CA 95616. 355