NUTRIENT DYNAMICS IN 3 WATER BASINS: AN ANALYSIS OF THE FACTORS EFFECTING EUTROPHICATION IN LAKE DAVIDSON

Eutrophication, including related thermal stratification, depleted dissolved oxygen, and increased growth of primary producers, is generally thought to be anthropogenically driven in suburban areas. However, suburban areas actually contain a large variety of land use practices and the impacts of individual land use practices can vary. Lake Davidson is a small reservoir that is semi-connected to Lake Norman. To address how different land use practices impact eutrophication in Lake Davidson, we examined three inflow points of varying land uses. Each entry point represents a different form of land use: a forested stream, a neighborhood retention pond, and a farm retention pond. Flow was monitored through each of these points as well as in the three basins: Lake Davidson, the neighborhood pond and the farm pond. Due to a lack of precipitation over the course of the study period, the question of which land use practice was most responsible for nutrient input into Lake Davidson was inconclusive. Instead, we focused on sampling directly within two ponds and Lake Davidson itself. Further, we examined temperature, DO, and chlorophyll a depth transects collected by the county. We determined that Lake Davidson existed in a state of stratification during the summer and early fall. There was a decreased amount of nutrients at the surface of the water at this time likely due to the high concentration of primary producers within the water column, which was measured by the concentration of chlorophyll a. As the weather cooled off and precipitation increased, a decline in the concentration of chlorophyll a corresponded with an increase in nutrients in each basin. The higher concentration of nutrients correlated with an increase in the death of primary producers which release nitrogen and phosphorus that were pertinent to their life cycle. The increase in precipitation and death of primary producers are both responsible for the change in the amount of nutrients in the three basins.