Prescribed burn creates pulsed effects on a wetland aquatic community

Abstract

Fire in uplands and wetlands results in a release of nutrients and increased light in the burned area. However, fire effects on aquatic community dynamics are not well understood. We hypothesized that the addition of light and nutrients resulting from prescribed burns in wetlands increases periphyton biomass and supports increased standing stock of marsh fishes. In the oligotrophic Everglades of Florida, USA, we conducted a 2 × 2 factorial experiment using prescribed burns over standing water (increased nutrients and light), mowing with removal of above-water vegetation (no nutrient increase), and shade houses (no light) to test the prediction that fire effects would lead to more periphyton biomass and greater abundance and size of fish compared to other treatments. We observed increased periphyton percent cover and biomass per area in response to fire treatments. Fish abundance showed a short-term increase in burned plots. Fish length, mass, and condition factor did not respond consistently to treatments, though some species responded to specific treatments. Wildfires in dry marshes that may combust organic soils and vegetation may impact wetlands more than prescribed burns in flooded marshes. Our study suggests that wetland fires can affect aquatic animal and plant community structure, at least for short periods post-fire.