Browsing by Author "Beyger, Lindsay Alexandra"

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Growth, survivability, and reproductive effects of pulse-dosed endosulfan on jordanella floridae (florida flagfish) over one complete life-cycle
(2009-08-01) Beyger, Lindsay Alexandra; Holdway, Douglas
Endosulfan is a commonly used organochlorine in Durham Region, Ontario Canada which has known toxic effects on non-target organisms including fish. This research investigated the effects of endosulfan on Florida flagfish (Jordanella floridae), using both continuous and pulse-exposure. The 96 hour continuous exposure LC50 in larval flagfish was 4.35 μg/L; sub-lethal observations included hyperactivity, convulsions, and some axis malformation. The effects of a 4 hour endosulfan pulse-exposure on 7-8 day-old larval growth, reproduction, and survivability were investigated over one full life-cycle. The 4 hour pulse-exposure LC50 value for larval flagfish was 49.7 μg/L; there were no growth or reproductive effects of endosulfan pulse-exposure up to the highest exposure concentration of 10 μg/L. Thus, the life-cycle 4-h pulse-exposure no observed effect concentration (NOEC) and lowest observed effect concentration (LOEC) were 3.2 and 10 μg/L endosulfan, respectively, due to significantly higher mortality.
The impact of restricted ration and chemical stressors on Rainbow trout (Oncorhynchus mykiss) and American flagfish (Jordanella floridae)
(2017-12-01) Beyger, Lindsay Alexandra; Holdway, Douglas
This research aimed to increase the understanding of the impact of multiple factors including both environmental and chemical stressors and their effects on fish survival, growth, and reproduction. Rainbow trout (Oncorhynchus mykiss) were used to assess the impact of restricted feed on acute toxicity and it was found that prior feeding regime is unlikely to affect short-term toxicity results. These findings are important when considering the potential implications in both setting regulatory guidelines, and in the natural environment. American flagfish (Jordanella floridae) were used to assess the impact of environmentally relevant concentrations of ibuprofen, naproxen, and 17 α- ethinylestradiol (EE2) alone and in mixture on both reproduction and subsequent sensitivity to offspring. Both a short-term reproduction test, and multi-generational study were used to assess a variety of endpoints. The partial life-cycle study noted a significant decrease in fertilization as a result of exposure to 0.1 μg/L naproxen, and 10 ng/L EE2, as well as a significant increase in egg production as a result of exposure to 0.1 μg/L ibuprofen. The multi-generational study demonstrated a significant decrease in fertilization after exposure to the highest concentration of mixtures of ibuprofen, naproxen, and EE2 for both generations. There were also significant changes in egg production. In both studies subsequent toxicity to offspring was not altered significantly. Overall, there appeared to be reproductive impacts related to pharmaceutical exposure either via either short-term exposure, or over multiple generations. Conducting studies that encompass both chemical and environmental stressors has always been challenging. In surface waters, wild fish may be exposed to numerous compounds over multiple generations with many different stressors and modifying factors. Thus, it is important to consider multiple factors together in order to understand the true scale of potential contaminant impacts on fish populations.