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Tuesday, May 27, 2008
360
Effects of experimental nutrient enrichment on benthic algae and algal-derived DOC in a boreal wetland, Alaska
Kevin H. Wyatt and R. Jan Stevenson. Zoology, Michigan State University, 203 Natural Science Building, East Lansing, MI 48824
Factors that regulate benthic algae have not been extensively studied in boreal wetlands. We investigated the effects of nitrogen (N), phosphorus (P), and silica (Si) enrichment on benthic algal productivity, taxanomic composition, and algal-derived dissolved organic carbon (DOC) in a freshwater marsh, Alaska. We constructed 20 mesocosms in-situ, and randomly assigned each to one of four nutrient treatments or a control, with four replicates each. We added individual doses of N (1.0 mg L-1 NO3), P (0.1 mg L-1 PO4), Si (10 mg L-1 SiO2), or a combination N, P, and Si (NPSi) to mesocosms every four days for 24 days during the summer growing season. Only the NPSi treatment increased benthic algal biomass to levels significantly higher than the control. DOC concentrations increased with algal biomass across all treatments, but DOC concentrations in the NPSi treatment were significantly higher than treatments with either nutrient alone. Coccoid cyanobacteria and filamentous green algae such as Mougeotia were favored in the NPSi treatment, whereas chrysophyte cysts were abundant in individual nutrient treatments and the control. Changes in algal productivity, community composition, and algal-derived DOC with nutrient enrichment could have consequences for wetland biogeochemical processes and food-web dynamics.
Web Page: Algae, Nutrients, Wetlands
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See more of The Nabs 56th Annual Meeting (25-28 May, 2008)
See more of Contributed Sessions
See more of The Nabs 56th Annual Meeting (25-28 May, 2008)