John De Tuncq, “Seasonally-Dependent Stratification of Temperature and Conductivity in the Milwaukee Harbor”
Mentor: Russell Cuhel, Freshwater Sciences, Freshwater Sciences (School of)
Poster #193
Milwaukee Harbor connects Lake Michigan with 882 square-miles of watershed in southeastern Wisconsin. This estuary has been labelled an “Area of Concern” by the Environmental Protection Agency, making it the focus of projects that seek to improve human interactions with freshwater. In the Milwaukee Harbor, two essential components of primary production come about: nutrients that travel downstream, and light that penetrates the nutrient-dense discharge after it mixes with more translucent lake water. Resulting growth of diatoms, a type of algae that is nutritious food for fish, makes the Milwaukee Harbor a critical component of larval fish recruitment, which has been stunted since the invasion of Dressenid mussels and resulting regime shift around the early 1990’s. Significant subsurface geological and physical hydrographic features limit water movement. Thermal stratification prevents water from mixing across a temperature gradient. External drivers like weather can facilitate the movement of water, potentially breaking down mixing barriers. Vertical sampling is therefore necessary for understanding circulation mechanisms of Lake Michigan. During a four-dimensional study (latitude-longitude location, depth, and time) I began developing skills in identifying physical water characteristics describing seasonally-dependent stratification of temperature & conductivity in southwest Lake Michigan’s Milwaukee Harbor. My work as a SURF student in 2024 used weather patterns and stream discharge to move water content around harbor regions to feed plankton communities.