PARENT SESSION
Poster Session # 17: Aquatic Systems.
Thursday, August 7 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
The effect of water velocity on the periphyton taxonomic composition of mesocosms in the Everglades.
Hiaasen, Barbara*,1, Volin, John 1, Simmons, Steven1, 1 Florida Atlantic University, Davie, FL
ABSTRACT- Numerous studies conducted within lotic systems have shown that the structure and composition of freshwater periphyton communities are sensitive to many variables, including phosphorus availability and water velocity. Phosphorus uptake by periphyton is influenced by the metabolic characteristics of the component algal species. Differences in phosphorus uptake at different water velocities could thus be mediated by differences in periphyton composition. The primary objective of this research was to investigate the effects of water velocity on taxonomic composition of periphyton communities growing within artificial mesocosms at flow rates representative of Everglades marsh communities. These mesocosms received water from Stormwater Treatment Areas (STAs) constructed in the Everglades to serve as filter marshes for wastewater with high nutrient loads. A unique mesocosm design was utilized to control velocity, while maintaining equal hydraulic loading rates, residence times and colonizing surface between velocity treatments. The slow and fast water velocity treatments were 0.22 cm s-1, and 2.0 cm s-1, respectively. A comparative taxonomic analysis of genera using DIC and epi-fluorescence light microscopy was performed to examine periphyton relative abundance, generic diversity, and taxonomic differences within and between treatments. Periphyton tissue phosphorus and nitrogen levels, as well as numerous other metrics including dry weight biomass and water column phosphorus, nitrogen, pH and temperature, were determined. Analysis of initial samples has revealed clear differences in periphyton composition, particularly with regard to the relative proportion of diatomic and blue-green algal species present. Studying the effects of water velocity on periphyton communities provides data that can be used to optimize the design of STAs and increase the efficiency of nutrient removal technologies used in Everglades restoration.
Key words: Everglades, periphyton, phosphorus