Date of Completion
Honors College Thesis
Dr. Ana M. Morales-Williams
Lake Carmi, Paleolimnology, Diatoms, Sediment Core
Vermont lakes are changing rapidly in response to interacting climate and watershed disturbances. Understanding and predicting the biological response to disturbance in these systems is limited by a lack of long-term biological monitoring records. Paleolimnology is a powerful tool that allows us to characterize environmental change over annual to multidecadal timescales through analysis of lake sediments. Lake Carmi, located in Franklin, VT, is a eutrophic lake that receives high inputs of nitrogen and phosphorus from the watershed and frequently experiences cyanobacteria blooms. The lake is an upstream tributary of Missisquoi Bay, Lake Champlain, and is surrounded by land primarily used for agriculture. In order to reconstruct the trajectory of eutrophication in this lake, 10 samples were taken from a sediment core and the paleo-diatom record was analyzed for relative genus and species abundance. As expected, we found increases in taxa, including Fragilaria crotonensis and Aulacoseira granulata, in the upper section of the core which are associated with high nutrient loads and serve as an indication that the lake has not always been eutrophic as it is today. These and other taxa including Aulacoseira alpigena and Aulacoseira ambigua demonstrate the lake’s response to nutrient loading and physical disturbances in the lake and will be important to monitor in the future to inform the biotic response to nutrient remediation. The sediment diatom community provides insight into how Lake Carmi is responding to nitrogen and phosphorus nutrient loading and is the first step towards understanding its history and future trajectory to inform management decisions.
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Wasserman, Sarah R., "Understanding long-term environmental change in Lake Carmi, VT, using the paleo-diatom record" (2022). UVM Honors College Senior Theses. 514.