Creation of a Virtual Aquatic Mesocosm Using Stella Software

This study creates both virtual and physical, closed, aquatic mesocosms. Each mesocosm consisted of a 10 gal aquarium with an unspecified proportion of water and air. The contents of the aquarium included several crayfish, dechlorinated water, gravel, and submerged aquatic and terrestrial plants. The mesocosm was self−sustaining, airtight, watertight, and food tight. By reaching equilibrium between primary production, waste production and degradation, food consumption, and respiration (consumed oxygen and produced carbon dioxide), it was possible to keep the physical system self−sustained for up to a month. Parameters obtained from the physical mesocosms describe how changes in some parameters affected others. The ecological considerations that were important for the modeling procedure dealt with the trophic levels (producer, consumer, or decomposer) of the individual organism communities and their relationships. We defined the equations and parameters that describe the transfers of mass and energy between the organisms and their physical environment. The virtual mesocosm was based on a series of models for growth, oxygen consumption, biodegradation, nitrogenous component degradation, photosynthesis, and respiration. Development of the Stella model was an iterative process; the results of successive simulations were compared with results from physical crayfish aquaria to calibrate the model for improved accuracy.