Experimental Assessment of Phosphorus Effects on Algal Assemblages in Dosing Mesocosms

Periphyton covered by calcareous precipitations in the Everglades is mostly dominated by cyanobacteria (Cyanoprokaryota, blue-green algae). In some areas of the Everglades, diatoms, desmids, and a few species of filamentous green algae form a significant part of the periphyton. Filamentous green algae (e.g., Spirogyra spp. or Mougeotia spp.) are found mostly in areas with elevated nutrient levels (Van Meter 1965; Wood and Maynard 1974; Swift and Nicholas 1987; Vymazal and Richardson 1995). It has been repeatedly reported that the major factor affecting periphyton growth and species composition is water quality and, especially, phosphorus concentration in the water (Browder et al. 1981; Swift and Nicholas 1987; Rader and Richardson 1992; Vymazal et al. 1994; McCormick and O’Dell 1996; Raschke 1993; McCormick et al. 1996, 1998; Stevenson and Richardson 1994; Pan et al. 2000).

The major objectives of this study were (1) to evaluate the effect of phosphorus concentration on species variability and relative abundance of algae and cyanobacteria in natural periphyton communities and (2) to compare periphyton communities growing on natural vs. artificial substrates.