The effects of nutrient loading from avian breeding colonies into aquatic/marine ecosystems have been well documented. Documented influences include increased productivity of aquatic/marine macrophytes, elevated sediment nutrient concentrations, and increased densities of zooplankton and planktivorus fishes. The primary pathway of nutrient export from the rookery is through excreta from adult birds and their offspring. This study examined the influences of a 400-nesting pair rookery of cattle egret (Bubulcus ibis) in 1990 and a 75-nesting pair rookery of cattle egret in 1991 on a man-made freshwater treatment marsh in east central Florida. Because the fundamental intent of the created marsh (study site) was the removal of nutrients, primarily nitrogen and phosphorus, from advanced treated wastewater prior to discharge into public surface waters, the main objective of this study was to document the effects of the avian breeding colonies on water quality within the system. Secondary objectives of the study were to document influences on phytoplankton density and aquatic faunal community structure, as well as to estimate spatial and temporal limits of rookery influences. The results indicated significant water quality differences between rookery and reference sites during 1990 and 1991. The results also indicated significant differences between phytoplankton productivity and aquatic macroinvertebrate community structure between rookery and reference sites during 1990 and 1991. The effects of nutrient loading from the rookeries were confined to within 150 m and background water quality conditions were regained within one month of rookery abandonment. In effect, the 1990 and 1991 rookery sites were characterized as limited, transient "islands" of increased eutrophication within the marsh.
Stout, I. Jack
Master of Science (M.S.)
College of Arts and Sciences
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Burney, James L. Jr, "Effects of avian breeding colonies on a man-made freshwater marsh in East Central Florida" (1995). Retrospective Theses and Dissertations. 3160.