Comparing the dissolved oxygen, nutrient levels, macroinvertebrates, and chlorophyll A levels of Burt Lake and Douglas Lake.

Abstract

Lakes attract humans, inevitably causing development along lake shores. It is important to know how development is affecting the ecosystems of these lakes. To test the effects of human development, we compared the nutrient levels, chlorophyll A and amount of macroinvertebrates in two northern Michigan lakes, Douglas Lake and Burt Lake. Burt Lake has almost twice as many residences per mile of shoreline than Douglas Lake. We sampled dissolved oxygen, nutrient levels (phosphorus and nitrogen), macroinvertebrates, and chlorophyll A from two sites in undeveloped areas of each lake, two in developed areas of each lake, and two in the middle of each lake with three samples at differing depths. We also measured dissolved oxygen in each area and sites had a constant temperature. We hypothesized that Burt Lake would have higher levels of nitrogen, phosphorous, and chlorophyll A because of nutrient runoff and that Douglas Lake would have a higher proportion of Ephemeroptera, Plecoptera, and Trichoptera insect orders and higher Dissolved Oxygen levels. We found that there was a significantly higher amount of total phosphorous in Burt Lake, while the dissolved oxygen was only higher in Douglas Lake in the undeveloped areas. There was no significant difference in the amount of soluble reactive phosphorous or nitrogen between the two lakes. Though no significant difference was found in EPT proportions, Douglas Lake had slightly higher proportions than Burt Lake in both developed and undeveloped areas. Nutrient runoff in each lake could be higher later in the summer because of increased use of lawn fertilizers and general human activity on the lakes. Many of the findings showed the overall water quality to be slightly better in Douglas Lake than in Burt Lake.