Poster Presentation Society for Freshwater Science 2026 Annual Meeting

Predator-prey interactions and body morphology of freshwater species under thermal stressors. (135786)

Charlie Wyman 1 , Brianna Stevenson 2 , Coco Wharry 1 , Clare McGowan 1 , Katie Ellis 1 , Poe Kyaw 1 , Ashlee Fiorito 1 , David Nguyen 2 , Sofie Lorenzo 2 , Lauren Lee 1 , Leah Gulick 1 , Annika Rose-Person 2 , Tiffany S Garcia 3 , Scott A Griffith 4 , Betsy A Bancroft 1 2
  1. Environmental Studies & Sciences, Gonzaga University, Spokane, WA, United States
  2. Biology, Gonzaga University, Spokane, WA, United States
  3. Fisheries and Wildlife, Oregon State University, Corvallis, OR, United States
  4. Mathematics & Computer Science, Whitworth University, Spokane, WA, United States

Freshwater ecosystems are critical for providing numerous ecosystem services, but they are highly susceptible to the effects of climate change. Climate change has increased average temperatures and led to more frequent extreme heat events, which can interact with predator-induced stresses to change freshwater species’ interactions, behavior, growth, morphology, and survival rates. We tested the effects of press and pulse heat events in the form of an elevated temperature treatment (press event) and two different types of extreme heat events (pulse events) in tandem with the presence or absence of dragonfly (family Aeshnidae) nymph predators on the growth, development, morphology, and behavior of Pacific chorus frog (Pseudacris regilla) tadpoles. We used a 2x4 factorial design with two levels of predator treatment (present/absent) and four levels of heat exposure (baseline, baseline +3°C, baseline + short high-intensity heat wave, baseline + long moderate-intensity heat wave). Each treatment was replicated 12 times for a total of 96 tanks. Tadpoles were held in 9-L glass tanks and predator treatments were applied by placing dragonfly nymphs into the tanks in clear plastic cups with perforations. Tadpole and dragonfly size and morphology were assessed at the beginning and end of the experiment. Preliminary findings show that tadpole mass change is influenced by temperature and predator presence—tadpoles grew less with the predator present  (p<0.05). As the accumulated heat exposure increased, tadpoles developed more quickly overall (p<0.001), but this trend was nearly significantly less strong with a predator present (p=0.067). Additionally, all treatments with temperature increases led to an increased tadpole development rate (p<0.01). Lastly, we found that dragonflies exposed to the short heatwave attacked tadpoles faster than dragonflies exposed to any other treatment (p<0.01). In all other treatment groups, dragonfly attack time decreased with increasing tadpole size (p<0.001). Understanding predator-prey interactions in different temperature scenarios provides context for community responses under climatic stressors. Our results contribute to the general understanding of how freshwater communities respond to climate change, allowing us to better protect and preserve these important and threatened ecosystems.