Master of Science, The Ohio State University, 2022, Environment and Natural Resources

Artificial light at night (ALAN) is a growing environmental stressor due to human expansion and increased urbanization. ALAN has shown to have significant impacts on a suite of taxa and on multiple levels of biological organization, but most research has focused on individual to population levels of biological organization. Furthermore, there has been a disproportionate research emphasis on terrestrial vs. aquatic ecosystems. In this study, I investigated the impacts of ALAN on riparian mammal space use and food webs along 12 small streams in Columbus, Ohio, USA. Seasonality and time of day were the strongest drivers of mammal community composition along streams, despite the presence of ALAN. Seasonality, sediment size, and other site-level differences, but not ALAN, were associated with total mammal space use and species richness. No species-specific small mammal captures or species/guild-specific camera-trap encounters were impacted by ALAN. In the context of this study, sediment size is likely a proxy for either stream size or urbanization but also a potentially important structural factor related to small-mammal movement across streams. ALAN presence was related to the proportion of energy derived from aquatic vs. terrestrial primary producer pathways in the genus Peromyscus, the only small mammals with sufficient sample size to estimate diet proportions. At illuminated reaches, Peromyscus nutritional subsidies derived from aquatic primary producer pathways (i.e., originating from stream periphyton) were 1.2% lower at lit compared to unlit reaches. Canopy cover was also associated with the proportion of energy derived from the terrestrial primary producer pathway that is indirectly consumed by Peromyscus (i.e., originating from aquatic detritus). Site – as a random effect in linear-mixed models – explained the greatest amount of variation in the proportion of energy derived from different primary producer pathways. Overall, I did not find e (open full item for complete abstract)

Committee: Mažeika Sullivan (Advisor); Robert Gates (Committee Member); Stanley Gehrt (Committee Member) Subjects: Ecology; Environmental Science; Natural Resource Management; Wildlife Conservation; Wildlife Management

PHD, Kent State University, 2009, College of Arts and Sciences / Department of Biological Sciences

In the portion of the food web more reliant on living, standing crop plant material—the “green” portion of the food web, decreased plant species richness may result in increased abundance of insect pest species and lower insect species richness. Nutrient loading not only increases plant standing crop biomass, but also plant litter production, which can increase the basal food resource for the detrital community, resulting in increased detritivore and epigeal predator abundances. Furthermore, plant litter increases habitat complexity, which can also increase arthropod abundance and diversity. These important factors affect both biodiversity and trophic interactions, and this experiment has measured these effects in one of the largest spatial-scale studies of its kind. The plant community largely responded as predicted by biodiversity-productivity theory, but some notable aspects of the plant community did not. The loss of forb species due to fertilization was consistent with the abundance-based mechanism of diversity loss due to fertilization. However, it is striking that fertilization significantly affected only forb species richness, not forb species biomass, contradicting biodiversity-productivity theory. Also contradicting conventional theory, grass species richness showed no response to fertilization, but grass species biomass was strongly affected by fertilization. Epigeal arthropod community responses to fertilization were mixed. When looking at beetles and spiders separately, taxa that are typically used as indicators, fertilization increased abundance and biomass as predicted by biodiversity-productivity theory, but species richness was not affected as predicted. Beetle species richness actually increased in fertilized plots, as did the species richness of linyphiid spiders. Moreover, the detritivorous prey of the beetles and spiders did not increase in biomass or abundance as would be expected by biodiversity-productivity theory. Further contradicting theor (open full item for complete abstract)

Committee: Mark W. Kershner Ph.D. (Advisor); James L. Blank Ph.D. (Committee Member); Alison J. Smith Ph.D. (Committee Member); Lauchlan H. Fraser Ph.D. (Committee Member); Randall J. Mitchell Ph.D. (Committee Member) Subjects: Biology; Ecology