Comparative lake study of Douglas Lake, Cheboygan County, MI.

Abstract

We performed a comparative lake survey on Douglas Lake so as to determine its trophic status. On June 30, 1999, we collected data from different regions of the lake, later analyzed it, and used it to ultimately define at which stage in the eutrophication process Douglas Lake presently belonged. Using biological, physical, and chemical parameters, we established that Douglas Lake was mesotrophic. In order to come to this conclusion, we had to assimilate a plethora of data, profiles, and identifications. In terms of physical characteristics, the watershed of Douglas Lake was primarily highlighted. It showed that Douglas Lake was surrounded by a relatively low watershed area: lake area ratio. In addition, the watershed provided a rich source of organic input. Douglas Lake's drainage basin was medium-sized and mostly forested. The basin morphometry juxtaposed aspects typical of both oligotrophy and eutrophy. Chemically-speaking, we used nutrient data to generate profiles that later proved to be indicative of our lake's trophic status. The dissolved oxygen profile displayed a textbook clinograde that is prevalent in eutrophic lake ecosystems. Other nutrient profiles depicted our lake to be eutrophic as well. For example, our sulfate-sulfide profile reflected high oxygen levels in the epilimnion and low to anoxic conditions in the hypolimnion. As for the biological organisms gathered, we discovered that Douglas Lake was host to a healthy amount of phytoplankton, zooplankton, fishes, macrophytes, and aquatic invertebrates. Normal levels of diversity and biomass for mesotrophic lakes were observed. Based on the above evidence and Carlson's trophic state indexes, we designated our lake to be mesotrophic. Being mesotrophic meant that our lake demonstrated oligotrophic, mesotrophic and eutrophic tendencies.