INTERACTIVE AND INDIVIDUAL EFFECTS OF ANTHROPOGENIC ENVIRONMENTAL STRESS ON FRESHWATER ORGANISMS

In this dissertation, I explore how human actions (climate change, road salt, land use change, species invasions) interact with and influence morphology, disease, and population dynamics in freshwater organisms (amphibians and aquatic crustaceans). First, I examined how the incidence and timing of disease epidemics in native species (Daphnia dentifera) caused by a generalist parasite (Metschnikowia bicuspidata) influenced the success and impact of an invasive species (Daphnia lumholtzi) in freshwater zooplankton (Chapter 1). In the following chapter, I explored how host-parasite interactions are affected by the interactive effects of multiple environmental stressors, focusing on American bullfrog tadpoles (Lithobates catesbeianus), two of their common parasites (Batrachochytrium dendrobatidis (Bd) and trematode parasites in the family Echinostomatidae), and two common stressors (fluctuating temperatures and sublethal road salt pollution; Chapter 2). Finally, I investigated how the combination of climate (temperature and precipitation) and land use (developed and/or forested area) change have influenced the body size of a common toad (Fowler’s toad, Anaxyrus fowleri) from 1930 – 2020 utilizing museum specimens (Chapter 3). Together, this research establishes how emerging and persistent anthropogenic environmental stressors will interact to affect morphology, disease, and population dynamics in vulnerable freshwater organisms.