Doctor of Philosophy, Miami University, 2024, Biology
Midwestern North American lakes, including the Laurentian Great Lakes, are experiencing significant increases in water transparency due to invasive Dreissenid mussels and improved watershed management practices. Climate change loss of winter has reduced annual ice cover on the lakes. Increases in water transparency combined with the absence of ice cover in the winter may lead to an increased risk of exposure to damaging ultraviolet radiation (UV), which is known to regulate the early life stages of fish. Despite these potential increases in underwater UV, very little is known of the current day UV transparency throughout the Great Lakes, nor the UV tolerance or mechanisms of protection of the early life stages of a culturally, economically, and ecologically important subfamily of native Great Lakes fish: Coregonine (i.e., Lake Whitefish [Adikameg; Coregonus clupeaformis], Cisco [Otoonapi; C. artedi], and Bloater [C. hoyi]), nor an economically important invasive prey species of fish: Alewife (Alosa pseudoharengus). This dissertation investigated 1) the spatial and temporal UV transparency patterns across the Great Lakes, 2) the ability for UV to accelerate the hatching of native Cisco eggs, 3) the UV tolerance, mechanisms of protection, and sublethal consequences of exposure to UV among two life stages, four species and multiple populations of fish and 4) the influence of UV on the vertical distribution of larval Alewife and Bloater within Lake Michigan. Although long-term offshore UV data does not exist, long-term nearshore UV data suggest shallower UV exposure correlated with increasing dissolved organic carbon concentrations. Laboratory experiments revealed that developing Cisco embryos exposed to UV have the potential to hatch 30 days earlier than embryos unexposed to UV, the egg life stage of all native coregonines tested had a higher UV tolerance than the larval life stages, and the UV tolerance among species and populations of the same species varied. Field s (open full item for complete abstract)
Committee: Craig Williamson (Advisor); David Bunnell (Committee Member); Jennifer Schumacher (Committee Member); Michael Vanni (Committee Member); Thomas Fisher (Committee Member)
Subjects: Biology; Ecology; Freshwater Ecology; Limnology; Organismal Biology