Wetland ecology--Florida--Everglades

One factor that potentially controls the distribution and density of wading bird
prey within open-water marsh habitats during seasonal drying events is the amount of
available aquatic habitat, which is partly a function of the amount of microtopographic
relief at a given location. To determine how microtopographic relief affects prey
concentrations during dry-downs a simulation model was developed and run using
empirical microtopographic data collected from the Everglades. The simulation suggests
that those locations within the marsh with higher levels of microtopographic relief
concentrate prey earlier during the dry-down period and potentially to greater densities
overall. In addition, a model selection analysis was performed on field data to determine
which set of factors displayed the greatest effects upon prey concentrations during drydown
events. When examining the best selected a priori model it appears that the
amount of available aquatic habitat, water depth, and macrophyte density have the
strongest affects upon concentrations of prey during a seasonal drying event.

The vulnerability of prey to capture plays a fundamental role in determining
overall prey availability for wading birds. Structural complexity can act to decrease prey
vulnerability and influence foraging habitat selection. To determine how structural
complexity can affect habitat selection I conducted a use vs. availability study throughout
the Florida Everglades in 2005 and 2006. Results indicated that wading birds chose
foraging sites that had less emergent vegetation and a thicker flocculent layer relative to
random sites. Submerged vegetation, and the height of emergent vegetation did not
affect wading bird site selection. A difference in habitat selection between years was
evident due to hydrological conditions. Ideal hydrological conditions are probably the
most important parameter to wading bird success. Other factors affecting prey
vulnerability became increasingly important in years of poor hydrology, probably
because the penalty for choosing low quality foraging habitat would be greater than in
years of more optimal conditions.

To improve water quality as part of a large restoration effort, constructed herbaceous wetlands will be used as filters of high nutrient water. In this study, I tested whether mixed forested wetlands could also be used as nutrient filters. I examined water quality parameters within a forested slough isolated from direct anthropogenic disturbance and within an impounded forest wetland receiving direct agricultural effluent. Among the water quality parameters, TP and K concentrations in the forested slough were particular low. Although all nutrients, except TKN, were higher in the impounded wetland, nutrient concentrations within the wetland were lower at interior sites as compared to inflow water. Based on the use of chloride as a conservative tracer, this reduction resulted predominantly from biological and chemical processes, while physical processes played a minimal role. This study established that mixed forested wetlands can significantly reduce high nutrient levels in surface water.