A key question of the oligotrophic Everglades freshwater marsh is how sufficient energy is transferred from the primary producers through the food web to support an abundant, diverse array of top consumers, such as wading birds. The functional group of small fishes is the pivotal link in this energy transfer because of their attributes and the seasonal pulsing of water across the low but complex relief of the Everglades. The fish spread rapidly across the landscape during the rising waters and grow in population size by feeding on a diverse diet from lower trophic levels. As water levels recede during the dry season, fish come trapped in shallow depressions and concentrated to densities that can be efficiently utilized by wading birds and other predators.
Results/Conclusions
Here we used a spatially explicit model, GEFISH, to quantify this process and estimate the importance of the movement behavior and omnivory of the fish. We compare the results with independent data from an empirical study on a pond in the Everglades and show that the model accurately predicts both the observed concentration of fish and the changing population size of the wading birds feeding at the pond during the concentration phase of the fish. The model GEFISH is being used over broader areas of the Everglades to estimate hydrologic conditions that favor fish availability to wading birds.