The ecology of stormwater ponds in Brevard County, Florida: A comparison among land usages

Florida's landscape has been altered greatly by the growing number of man-made habitats called stormwater ponds. These ponds are created to mitigate for the changes in hydrology created by an increase in impervious surfaces and to reduce pollutant loads from urban, agricultural and industrial development. Most prior studies have focused on the efficiency of stormwater ponds in treating runoff. The object of this research was to determine if there were differences in diversity, richness, and composition of zooplankton and benthic communities due to differences land use surrounding stormwater ponds, location within ponds, and season.;Stormwater ponds were chosen from different land use categories (agricultural, residential, highways), and three locations (inlet, middle outlet) within each pond were sampled to represent a potential gradient in pollutant loading. Benthic and zooplankton samples (N=3) were collected quarterly over a two-year period from each location along with water samples for determination of nutrient concentrations (nitrate, phosphate, ammonia), Total Suspended Solids (TSS), Chlorophyll a abundance, turbidity, and the presence of pesticides (Atrazine and Endosulfan and its byproducts). Sediment samples were also collected for organic content analysis, and determination of concentrations of oil and grease, copper and zinc and pesticides (Atrazine and Endosulfan and its byproducts). Environmental parameters (temperature, salinity, dissolved oxygen, pH, sechhi depth) were also recorded at each sampling.;The pesticides, Atrazine and Endosulfan, were not detected in the water column or adsorbed onto sediment. Oil and grease levels were either undetectable or low and not significantly different among ponds with different surrounding land use. Metal analyses of sediments indicated no significant differences among land use or location for concentrations of copper and zinc. Total Suspended Solids (TSS) were not statistically different among land use categories but were slightly higher in residential ponds. Chlorophyll a was significantly higher in residential ponds compared to agricultural ponds and was lower in the fall compared to winter. Nutrient analyses showed nitrates and ammonia were generally higher in residential ponds than in agricultural and highway ponds were lower in agricultural ponds while phosphates were lower in highway ponds. Ammonia concentrations were marginally different among land use categories with a trend of residential ponds having higher levels compared highway and agricultural ponds. Percent organic matter was generally higher in sediment from residential ponds but there was a significant interaction between land use and locations.;There were 86 species of zooplankton and 96 species of benthic macroinvertebrates identified. No significant difference in diversity was found in zooplankton by location or land use but there was a seasonal difference with diversity being higher in the fall. Benthic faunal diversity was significantly higher in highway ponds compared to residential ponds. There were no significant differences among locations within the ponds, and seasonally benthic diversity was higher in the fall. Nonmetric multidimensional scaling (NMDS) results that composition of both zooplankton and benthic macroinvertebrate communities were similar among all the samples regardless of land use or location (stress=0.01). Species richness in zooplankton, however, was significantly higher in residential ponds and at the inlets of ponds, and zooplankton and benthic species richness were both significantly higher in the fall. Variations in diversity and richness are believed to be driven by differences in primary production associated with input of nutrients and seasonal changes in production and environmental conditions. Carlson Trophic State Indices indicated all ponds ranged from mesotrophic to hypertrophic, which was confirmed with the five most abundant benthic species being highly pollutant tolerant species.