Browsing by Author "Dobosenski, Jamie"

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    Effects of Whole-Lake Mixing on the Diet of Rainbow Smelt (Osmerus mordax)
    (2016) Dobosenski, Jamie; Heald, Emily; Hrabik, Thomas
    Rainbow smelt, an invasive coldwater fish species native to the eastern coastal US, were intentionally introduced into the Laurentian Great Lakes Region in the early 1900s to serve as forage for predatory fishes. Rainbow smelt reduce populations of native fish in the systems they invade. To eradicate invasive cold-water rainbow smelt in Crystal Lake, the lake underwent whole-lake mixing. The manipulation successfully created isothermic conditions and removed all coldwater habitat required by rainbow smelt. Although the induced mortality rate was significant (90%), the mixing did not eradicate rainbow smelt from Crystal Lake. For my research I hypothesized that a shift in diet may have helped the rainbow smelt population persist during the thermal manipulation. The mixing event removed the coldwater habitat, thereby inducing a spatial shift of rainbow smelt in an attempt to find new habitat. This movement could have changed the prey availability and prey selection, and those that were able to adapt to that change survived. There was evidence that rainbow smelt diet was effected by whole-lake mixing. Overall, the proportion of general zooplankton decreased during mixing and returned to a high proportion after mixing. The proportion of larger diet items increased during mixing. These finding may have future implications for management strategies.
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    Investigating invasive population genetics of rainbow smelt (Osmerus mordax) in the Laurentian Great Lakes Region
    (2018-08) Dobosenski, Jamie
    Increasing our understanding of aquatic invasive species is important because of the negative influence they can have on the economies and ecosystems of invaded regions by negatively affecting ecotourism as well as commercial and recreational fisheries. There is growing interest in how environmental variability (e.g. temperature) and stochastic invasion events (e.g. founder effect) affect the genetic composition of populations of invasive species. Rainbow smelt (Osmerus mordax) are a cold-water, planktivorous fish that spread into the Great Lakes basin in the early 1900s. We performed genetic analyses using microsatellites to determine if a temperature induced mortality event affected the genetic structure of a population of invasive rainbow smelt and to also investigate the influence stochastic invasion events have had on the genetic composition of invasive rainbow smelt populations across broad geographic ranges. Overall, there was no genetic difference in rainbow smelt collected before, during, or after the temperature induced mortality event. To investigate the influence stochastic invasion events have on populations of invasive rainbow smelt, we conducted population genetics analyses on rainbow smelt specimens from Lake Ontario, Lake Michigan, Lake Superior, and four inland lakes in Northern Wisconsin. Most population pairs had pairwise Fst values significantly different than zero except two comparisons. Based on clustering analysis and PCoA analysis, four distinct population clusters were identified. Overall, this study provides evidence that founder effects have more of an impact on invasive rainbow smelt population diversity than extreme population reductions.