Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4391233 | Ecological Engineering | 2006 | 11 Pages |
Abstract
Phosphorus uptake and release by periphyton mats were quantified in the Everglades Nutrient Removal Project (ENRP) to evaluate the potential for periphyton P removal. Short-term P uptake rates were determined by incubating cyanobacteria (Oscillatoria princeps and Shizothrix calcicola) and Chlorophycean (primarily Rhizoclonium spp.) algal mat samples for 0.5-2 h under ambient conditions in BOD bottles spiked with soluble reactive P (SRP). Cyanobacterial mats removed P more than twice as fast (80-164 μg P hâ1 gâ1 AFDM) as Chlorophycean mats (33-61 μg P hâ1 gâ1 AFDM) during these incubations. In a longer term study, fiberglass cylinders were used to enclose 1.8 m2 plots within the wetland and were dosed weekly for 7 weeks with: (1) no nutrients; (2) SRP (0.25 g P mâ2 weekâ1); or (3) SRP plus nitrate (0.42 g N mâ2 weekâ1) and ammonium (0.83 g N mâ2 weekâ1). Phosphorus uptake rates by this periphyton assemblage, which was dominated by the chlorophytes Stigeoclonium spp. and Oedogonium spp., were measured weekly and were similar among nutrient treatments on most dates, indicating that the algal storage compartment for P was not saturated despite repeated P additions. Decomposition rates and P loss by cyanobacteria and Chlorophycean mats were determined by measuring biomass loss and SRP release in darkened BOD bottles over 28-42 day periods under anaerobic and aerobic conditions. First-order aerobic and anaerobic decomposition rates for cyanobacterial mats (k = 0.1095 and 0.1408 dayâ1, respectively) were 4-20-fold higher than rates for Chlorophycean mats (k = 0.0066 and 0.0250 dayâ1, respectively) and cyanobacteria released considerably more P back to the water column. Our findings suggest that periphyton can be an important short-term sink for P in treatment wetlands and that retention is strongly affected by the taxonomic composition of the periphyton assemblage.
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Authors
Paul V. McCormick, Robert B.E. III, Michael J. Chimney,