Graeme Zaparzynski defends his thesis on Brook Trout Bioenergetics in Coolwater Streams
Graduate student Graeme Zaparzynski defended his thesis on August 10th, 2016 titled “Evaluating Foraging Habits and Estimating Prey Consumption and Growth of Brook Trout in a Coolwater Michigan Stream”. Graeme’s graduate committee included Mark Luttenton, Eric Snyder, and Carl Ruetz III.
Graeme conducted research in Cedar Creek, a tributary of the Rogue River, Kent Co. His thesis documents temporal prey availability in Cedar Creek, as well as temporal trends in brook trout prey consumption and important energy sources in their diet throughout the summer. Although aquatic prey abundance did not decrease throughout the summer in Cedar Creek, brook trout tended to consume fewer prey items from June to August and they disproportionately selected aquatic and terrestrial invertebrates found on the surface of the stream. Greater than 50% of the energy in brook trout diets came from aquatic macroinvertebrates in June and July, whereas almost 70% of the energy in their diets came from terrestrial macroinvertebrates in August. In addition to observing foraging trends, Graeme calculated instantaneous growth rates for fish that were recaptured throughout the study and used a bioenergetics model to estimate how the growth of brook trout would be effected if the thermal regime of Cedar Creek was disturbed. On average, recaptured trout displayed a negative growth rate, and their body condition decreased between the time they were initially captured and their final capture. The bioenergetics model estimates that brook trout in Cedar Creek would experience an 11-14% decrease in body weight with an average increase in water temperature of 1RC over the study period. Graeme’s thesis research highlights the importance of protecting the riparian canopy of cool and coldwater streams to help maintain stable water temperature, and promote food-web connectivity between aquatic and terrestrial habitats.
Graeme is helping finish additional research on Cedar Creek in partnership with the local Trout Unlimited chapter and hopes to pursue a career in aquatic ecology.