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Justin Wegner defends his thesis on brook trout thermoregulation and habitat selection

Justin Wegner defends his thesis on brook trout thermoregulation and habitat selection

On November 28, 2017, Justin Wegner successfully defended his Master’s thesis titled “Brook Trout Behavioral Thermoregulation and Habitat Selection in a Small Michigan Coldwater Stream: Implications for Successful Management”. His thesis committee members were Drs. Mark Luttenton, Carl Ruetz, and Eric Snyder.

Justin studied the movement, habitat use, and thermoregulatory behavior of brook trout in Cedar Creek, a small stream in southwest Michigan. Throughout much of their distribution, brook trout are threatened by increasing water temperatures caused by the loss of forested land cover and increasing global temperatures. Cedar Creek is negatively impacted by urbanization that causes increased surface runoff and elevated water temperatures. When water temperatures reach or exceed brook trout tolerance, brook trout often move to zones of coldwater refuge, such as coldwater tributaries or groundwater seepages, to maintain body temperatures within their preferred range. Justin’s research was conducted for the Trout Unlimited Home Rivers Initiative to help guide management efforts to improve and protect brook trout habitat in Cedar Creek. Brook trout in a forested section of Cedar Creek maintained body temperatures within the ideal range for growth for most of the summer and occupied habitats characterized by large woody debris and overhanging vegetation. In a section routinely clear-cut and bordered by agriculture, brook trout body temperatures were often above proximate ambient water temperatures, and brook trout occupied deep microhabitats with little cover. Several brook trout emigrated from the clear-cut section into a forested section; however, most brook trout were largely sedentary. These results illustrate the importance of a forested riparian corridor in providing woody cover and thermal refuge for brook trout. Justin recommends that management efforts to restore and protect brook trout habitat should focus on identifying limiting factors that provide important ecological benefits to Brook trout persisting in degraded habitats.

Justin plans to stay involved with research in the aquatic ecology field and pursue a career related to fisheries or stream ecology.

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