Cooperative Ecosystem Studies Unit, South Florida-Caribbean CESU

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A first version of a model of small fish in the Everglades, GEFISH, has been developed. GEFISH is a model for the lower trophic level food web and fish functional groups that are supported by the web. The model is spatially explicit, covering typical areas of Everglades landscape, and will be subject to the seasonal rise and fall of water levels. The objective of the new work will be to applied the model to three key classes of scenarios: (1) The lower elevation end of a marsh landscape will be bordered by a canal containing piscivorous fish, where the carrying capacity for the piscivorous fish can be varied; (2) a new piscivorous fish will be introduced that can move from the canal into the marsh area to relatively shallow areas of the landscape; (3) spreader swales will be introduced in the model that will form permanent refuges for smaller fish, but also will increase the potential habitat for piscivorous fish. Within each of these classes of scenarios, the effects of numerous variations of seasonal water patterns will be studied.GEFISH currently contains a limiting nutrient, phosphorus. In this new task mercury will be added to the model, so that the concentrations of mercury in each of the biotic components can be followed through time. In particular, the changes in mercury through seasonal changes over a year will be followed on daily time steps. Simulations over decade-level scales will be performed.

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