Simulazione dei processi trofici di ambienti acquatici

The numerical simulation model, discussed in this manual, is derived from a more simple one, which has been developed by us in the last few years. This first model, written in BASIC programming language under MS-DOS operating system, was able to perform computations of two phytoplanktonic species growth, which were nutrient, light and temperature limited. Further versions of the model saw an herbivorous zooplankter and acarnivorous included into simulations and, more over, different ways to input nutrients to the system, a day-night effect etc. The aim of our work in the field of system ecology was, and still is, to provide Italian reaserchers as well as students in biological and social sciences of modeling tools for their work. The model of this version, called AQMODL5, is in the reductionist view of ecosystem studies, this means that every component of the natural system has been analyzed singolarly and then related to the others in a mechanistic form. As the pieces of a puzzle give the idea of the whole design only when all assembled, so this model reproduces the reality (it does simulate it) imiting the effect that every single component produces on the ecological variables. In this sense it can be also considered deterministic, as it computes exactily the predicted values, and said dynamic, as all variables are time dependent. AQMODL5 has been developped to simulate plankton growth in an aquatic environment, so the different components that, some how, influence plankton's growth (such as water temperature, sun radiation, avalability of food, abbundance of predators, mortality and respiration rates etc.) have been analyzed. All the different kinds of relation between considered components and growth have been defined in detail, then relations have been translated in a formai language (mathematics). All math transformations have been assembled into differential equations that are solved by a computer in respect to a time increment factor. The results of the defferential equations are new predicted values of ecological variables. In this booklet the most new version of the model is decribed and discussed with an example. More informations about how the model has been built, and how all parameters have been chosen, can be found in the references referred to the authors. Copies of the programs on 5.25 in. diskettes can be obtained on request supporting a new disk