Okefenokee marshland before, during and after nutrient enrichment by a bird rookery

Abstract

Field measurements and data from the literature were used to construct a trophic model of Okefenokee Swamp marshland. Seasonal data were used to check dynamics of the model before, during and after simulated nutrient input from wading bird guano. The model gives reasonable estimates of the effects of enrichment on benthic detritus, aquatic macrophytes and phytoplankton, and conservative estimates of the increase of zooplankton and fish stocks. Simulated levels of the above components decreased toward nominal states after simulated abandonment by birds, and the rates of decrease generally followed field trends that were measured. The model indicates that nesting wading birds can have considerable effects on aspects of an aquatic ecosystem that are not normally associated with them (such as benthic detritus and fish). Significant links between components of aerial and aquatic systems are thus brought to light.