Physical Sciences and Mathematics Commons^™

Documenting The History Of Oxygen Depletion In Lake St. Croix, Minnesota, Using Chironomidae Remains In The Sedimentary Record, Caitlin E. Stewart

Masters Theses 1911 - February 2014

Lake St. Croix is a natural impoundment located at the southern end of the St. Croix River. Land use changes since European settlement (c. 1850) have resulted in nutrient runoff, eutrophication, and periodic oxygen depletion in the hypolimnion of Lake St. Croix. Establishing sound lake management practices requires knowledge of historical conditions obtained through paleoecological studies. Remains of non-biting midges (Insecta: Diptera Chironomidae) in lake sediments have been shown to be reliable indicators of past hypolimnetic oxygen conditions. Cores from two sub-basins in the lake were collected in 2006. Midge analysis indicated that shifts in species assemblages correspond to the …