Poster Presentation Society for Freshwater Science 2026 Annual Meeting

Thresholds in the responses of Pacific chorus frogs (Pseudacris regilla) to a gradient of temperatures and a heat shock (135329)

Annika Rose-Person 1 , Aristin Coones 2 , Josh David 1 , Makoa De Almeida 1 , Tereza Dudzik 2 , Katie Ellis 2 , Nora Fassler 2 , Holly Fijolek 1 2 , Sofie Lorenzo 1 , Mia Mastrangelo 2 , Clare McGowan 2 , Michael Schlotfeldt 2 , Carson Sellers 1 2 , Owen VanDerPuy 2 , Coco Wharry 2 , Tiffany Garcia 3 , Scott Griffith 4 , Betsy Bancroft 1 2
  1. Biology, Gonzaga University, Spokane, WA, US
  2. Environmental Studies and Sciences, Gonzaga University, Spokane, WA, US
  3. Fisheries and Wildlife, Oregon State University, Corvallis, OR, US
  4. Mathematics & Computer Science, Whitworth University, Spokane, WA, US

Climate change is altering the temperature regimes that organisms experience. In freshwater ponds, water temperature influences organisms’ growth and development rates. While many studies have demonstrated a strong effect of water temperature on amphibian growth rates, hatching timing, and emergence timing, few have investigated the thresholds at which organisms respond to differences in water temperature. In this study, we sought to determine the threshold at which the growth and development of Pacific chorus frogs (Pseudacris regilla) respond to increases in water temperature from egg through metamorphosis stage. We hypothesized that (1) the effect of water temperature on P. regilla growth and development would plateau at an increase from control tank temperatures of 3°C; and (2) a heat shock would decrease the response of P. regilla to increases in average temperatures. We assigned groups of three P. regilla eggs to a total of 94 tanks in a temperature-controlled room in Spokane, Washington that had one of seven dynamic temperature treatments representing baseline temperature (BT), BT+1°C, BT+2°C, BT+3°C, BT+4°C, BT+5°C, and BT+6°C. A subset of tanks experienced a heat shock treatment. We measured the date of egg hatching, date of tadpole metamorphosis, mid-experiment stage and mass of tadpoles, final mass of metamorphs, and morphological traits of metamorphs. Preliminary results indicate that eggs in warmer tanks hatched earlier (p<0.05). This advance in egg hatching timing was reduced in tanks that received the heat shock treatment compared with those that did not (p<0.05). For tanks without the heat shock, eggs reached a threshold in tanks with BT+4°C (p<0.01), where tanks warmer than BT+3°C experienced earlier hatch dates. Further data analysis on tadpole development rate, growth rate, and morphological characteristics is ongoing. This work identifies the thresholds at which a common amphibian responds to temperature stress. Further, we highlight the importance of an early-life heat shock to egg development in this amphibian.