Nutrient Limitation of Primary Production in Wetland Ecosystems

Science Center, Bent Corridor

Eutrophication in waterbodies often results from high nutrient levels, and is common in areas that receive runoff from agricultural lands due to high concentrations of nitrogen and phosphorus. Eutrophication causes turbidity, harmful algal blooms, and increased aquatic plant growth, while hindering the penetration of light and causing fish deaths. Historically, it has been thought that phosphorus was the main contributor to eutrophication in freshwater due to a positive correlation between phosphorus and chlorophyll a production. However, in recent years more attention has been paid to how algae reacts to combinations of nutrients. For example, when nitrogen and phosphorus are both added, algal biomass increased more than it had when each nutrient was added individually. And, when phosphorus and nitrogen are in abundance, it is thought that iron levels impact plant growth, due to its importance in photosynthesis and chlorophyll synthesis (Raven, 1988). A 7 day experiment was conducted in-situ in the Cow Creek wetland, in order to observe the ways in which algal growth responds to differing combinations and ratios of nitrogen to phosphorus to iron.