computer using the results from a water model based on

actual monthly rainfall at Ft. Myers (U. S. Department of

Commerce. National Oceanic and Atmospheric Administration,

1950 1975) for the 25-yr period from June 1950 through

May 1975. All models were written in the energy circuit

modeling language of H. T. Odum (1971).



 Basis for Models



Models of Water, Fish, and Wading Birds

 Model I is shown in Figure 10. The diagram indicates

most important compartments storagee) of the system, major

energy sources, energy sinks, pathways of energy

interaction, and thresholds (switching functions). Figure

11 is a key to the symbols used in Figure 10 and in the

model diagrams presented throughout this study. In Table 3

components of the model in Figure 10 are isolated and

explained in order to provide an understanding of the

model's structure and relationships. The symbols relate

flows to tanks in mathematical terms. Positive values are

flows entering the tank; negative values are those flows

leaving. The tanks change with time according to

differences between inputs and outputs. Flow rates change

with time according to the sizes of the tanks. Based on

the diagram differential equations are written for each

tank.