Lake (Coregonus clupeaformis) and round (Prosopium cylindraceum) whitefish are two species of cold-adapted freshwater fish that spawn in shallow (<10m) cobble beds in the Laurentian great lakes. Developing whitefish embryos are potentially exposed to various anthropogenic sources of warming, including climate change and thermal effluents discharged in the nearshore environment. Several studies have investigated the effects of elevated incubation temperatures on whitefish embryos (particularly lake whitefish) but little work has been done to examine post-hatch effects. Thermal preferenda (temperature preference) describe the range of temperatures an organism will occupy when given a choice and are traditionally thought to be species-specific. Temperature preference can be modulated by a variety of abiotic and biotic factors including environmental temperature and is typically correlated with optimal growth temperature for a species. Assays for thermal preferenda require at least 24 hours, which includes a long tank-acclimation period that limits throughput and thus impacts replication in the study. A shuttle box thermal preference assay was optimized from 24-hours to 4-hours; length of acclimation time and trial length had no significant impact on thermal preference. Whitefish were incubated at natural and elevated temperatures until hatching; all groups were moved to common garden conditions (15°C) during the post-hatching stage. Temperature preference was determined at 12 months of age; lake whitefish were also tested at 8 months. Round whitefish displayed a significant decrease in temperature preference when incubated at 2°C and 6°C compared to 0.5°C. Lake whitefish had similar temperature preferences regardless of age and incubation temperature. This suggests that there is a difference in thermal tolerance between these species, as round whitefish were more sensitive to elevated incubation treatments. This thesis identified a persistent effect of elevated incubation treatments on the thermal preference of juvenile round whitefish, lasting up to 12 months post-hatch, which highlights the importance of examining sub-lethal thermal effects and thermal plasticity of cold-adapted species. / Thesis / Master of Science (MSc) / Lake and round whitefish are cold-adapted freshwater species that spawn in shallow coastal water in the Laurentian great lakes. Anthropogenic warming from various sources (e.g. climate change, thermal effluent) has been shown to reduce survival of whitefish embryos, but few studies have investigated the effects of elevated embryonic incubation temperatures on surviving juveniles. Fish typically prefer a small range of temperatures (temperature preference) that they will occupy if given a choice, which can be affected by a variety of factors including early life thermal exposure. This thesis shows round whitefish incubated at elevated temperatures (2°C, 6°C) display decreased temperature preference up to 12 months post-hatch, while lake whitefish had similar temperature preference regardless of incubation temperature. Therefore, this thesis provides more evidence that round whitefish are a more thermally sensitive species.

Lake whitefish (Coregonus clupeaformis) are an ecologically, culturally and economically important species throughout the Great Lakes. Studying the larval period of ontogeny is important to increasing knowledge of population dynamics and monitoring ecological changes in lake whitefish populations. Larval lake whitefish have been studied across the Great Lakes since the 1930’s; however, there are major gaps in our understanding of the factors that affect distribution and abundance of larval lake whitefish. The goal of this study was to investigate the distribution and abundance of larval lake whitefish in a Great Lakes embayment, using Stokes Bay, Lake Huron as a case study. Plankton samples and environmental data were collected from mid-spring to early summer during 2011 and 2012. Plankton tows in 2011 (n=71, 21 April-03 June) revealed relatively high densities of larval lake whitefish as compared to other Great Lakes studies. Overall there was little relationship between environmental variables (temperature, dissolved oxygen, conductivity, depth) and larval lake whitefish distribution and abundance. Plankton tows in 2012 (n=25, 25 April-23 May) revealed a virtual absence of larval lake whitefish in Stokes Bay. The apparent 2012 year-class failure was concurrent with unseasonably warm temperatures and reduced ice coverage. Temperature-related hypotheses are evaluated in context with other possible explanations of a general year-class failure of lake whitefish during early life history. / Saugeen Ojibway Nation (SON)

Thesis (M.S.)--Oregon State University, 2011. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Lake and round whitefish are cold-adapted freshwater species with similar life histories and spawning behaviours. There have been several studies on the embryonic development of both species (particularly for lake whitefish), most utilizing constant temperatures. However, temperatures fluctuate in the field due to natural (e.g. seasonal changes) and anthropogenic (e.g. water discharged from once-through cooling processes) effects. Releases from once-through cooling processes may contain low levels of chemicals (e.g. morpholine) and radiation (e.g. tritium). This thesis examined and compared the impacts of thermal, morpholine, and radiation stressors on lake and round whitefish embryogenesis. To examine the effects of fluctuating incubation temperatures, lake and round whitefish were reared at constant temperatures, with seasonal temperature declines/inclines, transient temperature spikes, or seasonal temperature changes combined with temperature spikes. Round whitefish embryos had significantly higher mortality when reared at 8°C compared to lake whitefish, and seasonal temperature changes impacted development rate, growth, and hatch dynamics for both species. Temperature spikes had relatively little effect on development. The effects on embryonic development of chronic morpholine and low-dose radiation exposures were examined in round whitefish to compare with existing data in lake whitefish. Round whitefish embryos were more impacted by morpholine than lake whitefish (larger effects on growth and mortality at relatively lower concentrations) and v less impacted by low-dose radiation (little effect on growth or hatch dynamics). Post hatch, round whitefish embryos reared at 8°C, with rapid seasonal inclines, or with 500 mg L-1 morpholine had elevated mortality. All irradiated embryos had decreased mortality post-hatch compared to non-irradiated embryos. Thus, embryonic exposure to all stressors examined appears to alter post-hatch survival. This thesis better defines the effects of fluctuating incubation temperatures, chronic morpholine, and chronic radiation exposures on the embryonic development of lake and round whitefish. It also suggests that embryonic incubation conditions are important beyond hatching. / Thesis / Master of Science (MSc) / Lake and round whitefish are cold-adapted freshwater species. Both species play important ecological roles, with lake whitefish generally perceived as more economically and culturally important. Many studies have detailed lake whitefish embryonic development under constant stressors (e.g. temperature) but there are relatively few studies on round whitefish embryonic development. Both species experience seasonal temperature fluctuations in nature and may experience additional anthropogenic temperature, chemical, and radiation stress due to discharge from once-through cooling processes at thermal power plants, which may contain low levels of morpholine and radiation. Our study suggests that round whitefish embryos are more sensitive to elevated temperature and morpholine levels, but less impacted by chronic low-dose irradiation relative to lake whitefish embryos. The growth and development of both species are significantly affected by seasonal temperature changes.

Lake Vättern has been contaminated with high levels of polychlorinated biphenyls (PCBs) for decades, which could be due to the release of wastes from industries and urban communities surrounding the water system. This has especially had a negative effect on fatty fishes, which could accumulate large amounts of persistent organic pollutants (POPs) and thereby also become a source of environmental toxicants to humans through consumption. Most PCB analysis only quantify a handful of congeners, the so called indicator-PCBs (I-PCBs), but this might leave out important information. In this study, an existing analytical method was improved by supplementing with additional congeners to detect a larger set of PCB congeners in Arctic char (Salvelinus salvelinus) and European whitefish (Coregonus acronius) caught from Lake Vättern, Sweden. New pre-packed multilayer silica columns from CAPE technologies were tested and used to pretreat the fish samples prior to analysis with a Gas Chromatograph coupled to low-resolution Mass Spectrometer using Atmospheric Pressure Ionization (API GC/MS). It was found that modifications of the clean up method for PCBs were necessary, such as lowering the amount of hexane in the washing step and combining the two eluent fractions. The Arctic char and the European whitefish showed a fat content of 0.18% and 0.74%, respectively. Concentrations of detected congeners ranged from 0.5 to 1470 pg g-1 fresh weight (fw) in Arctic char and varied between 1.2 to 6550 pg g-1 in European whitefish. For Arctic char and European whitefish, the WHO2005-TEQ values were 0.4 pg g-1 fw and 0.6 pg g-1 fw, respectively. The greatest total PCB concentration of 25900 pg g-1 was measured in European whitefish. The total concentration of I-PCBs (#28, 52, 101, 138, 153, 180) was 3710 pg g-1 for the Arctic char and 13900e pg g-1 for the European whitefish. All obtained results were lower than those reported from other studies. Constructed congener profiles show that the two species have similar ratios of PCB #138 and #153. Differences are observed of PCBs with a higher chlorination grade, probably due to differences in migration patterns, habitats of the lake, diets, metabolism or bioaccumulation.

No description available.

Project (D. Min.)--Iliff School of Theology, 2006. / Includes abstract. Includes bibliographical references (leaves 162-166).

Project (D. Min.)--Iliff School of Theology, 2006. / Includes abstract. Includes bibliographical references (leaves 162-166).

This research focuses on the development, evaluation, and application of a mercury (Hg) mass balance model for predicting the accumulation of Hg in fish. This model requires accurate estimates of Hg elimination rate by fish and feeding rates to adequately predict Hg concentration in fish. An empirical model was developed to estimate Hg elimination by fish using data obtained from published experiments. This analysis showed that Hg elimination rate was overestimated in short-term experiments, positively correlated to water temperature, negatively correlated to body size, and that the elimination rate of inorganic Hg was faster than that of methylmercury. This empirical model was then incorporated in a Hg mass balance model to predict the concentration of Hg in fish. The Hg mass balance model accurately predicted Hg concentration in fish when it was combined with food consumption rates that were determined using a radioisotopic method. This analysis suggested that the parameters of the Hg mass balance model were adequate for predicting Hg concentration in fish. I also showed that Hg concentration tended to be underestimated by the Hg mass balance model when it was combined with feeding rates determined with a laboratory-derived bioenergetic model, probably because activity costs derived in the laboratory do not reflect activity costs of fish in the field. Beside predicting Hg concentration in fish, I showed that this mass balance model could also be used to estimate feeding rates of fish in the field by measuring the concentration of Hg in fish. This approach was validated using data obtained from a published experiment. It was also successfully tested using independent estimates of feeding rates obtained with a radioisotopic method. I applied this Hg mass balance model to compare the energy budget of sympatric populations of dwarf and normal whitefish (Coregonus clupeaformis). This analysis showed that dwarf whitefish consumed 40--50% more food than normal whitefi

Thesis (Ph. D.)--Michigan State University. Dept. of Fisheries and Wildlife, 2008. / Title from PDF t.p. (viewed Sept. 11, 2009). Includes bibliographical references. Also issued in print.