Gabor, CaitlinMiner, Krystie2022-05-252022-05-252020-05Miner, K. (2020). Artificial light at night alters physiology, behavior, and reproduction in the western mosquitofish (Gambusia affinis)</i> (Unpublished thesis). Texas State University, San Marcos, Texas.https://hdl.handle.net/10877/15808Human population growth and its associated effects have contributed to the rapid decrease of biodiversity worldwide. Artificial light at night (ALAN) is an anthropogenic pollutant that is increasing with the spread of urbanization and may contribute to biodiversity declines. ALAN alters the migration patterns of birds, communication in frogs, and impacts reproduction, behavior, and physiology of multiple other taxa. The effects of ALAN on freshwater organisms, however, are largely understudied as compared to terrestrial taxa. I investigated how ALAN affects the physiology, behavior, and reproduction of a widespread freshwater fish. Gambusia affinis are small livebearing fish often found in urban streams. I exposed groups of female G. affinis to either a natural light cycle or a constant 24-hour light cycle (ALAN) in the laboratory for 60 days. In another experiment, I exposed females to the same treatments in outdoor mesocosms for 32 days. I found that exposure to ALAN lowered glucose levels in brain tissue and decreased activity, but had no effect on cortisol release rates, reproduction, survival, or growth. This research is strengthened by measuring multiple metrics in response to ALAN and by incorporating both a field and laboratory component which confirm similar results. Ultimately, these results suggest that ALAN has detrimental effects even on a tolerant species and serious efforts should be taken to reduce its propagation.Text61 pages1 file (.pdf)enlightmosquitofishcortisolbehaviorglucoseThesis