Metabolic response of Ilyanassa obsoleta egg capsules to increased temperature under immersed and emersed conditions
Authors:Brittany Bjelde, Janet Garcia, Anne Todgham
Mentor:Anne Todgham, Assistant Professor of Biology, San Francisco State University
Egg capsules laid on the mud flats of intertidal zones are prone to increasing temperature challenges during emersion and immersion due to the nature of the tidal cycle. There has been little research done on the energy requirements of early developmental stages of organisms under emersion and immersion and whether increased temperature is an added stressor. In addition to temperature changes during low tide periods, climate change scenarios are predicting 2-4°C increases in temperature and increased frequency of heat waves in the next 90 years. In this study we examined changes in oxygen consumption of Ilyanassa obsoleta, an invasive mud snail, in response to increases in temperature under immersed and emersed conditions. We hypothesized that the embryos under immersed conditions and higher temperatures would consume the most oxygen since the higher temperatures would increase their metabolic demand. To test this hypothesis, we measured the metabolic rate of egg capsules at 16°C, 22°C, and 28°C in both emersed and immersed conditions. Our results showed that there was no effect of increased temperature treatments on the metabolic rate of the embryos in immersed conditions. However, there was an effect of higher temperature on the metabolic rate of embryos under emersed conditions where the metabolic rate increased at 28°C. The metabolic rate of immersed embryos showed temperature insensitivity that may have indicated that diffusion of oxygen through the egg capsule was efficient to meet the metabolic demand of increased temperature. Under emersed conditions, our data suggests that the effects of desiccation and increased temperature resulted in elevated energy demands of the embryos. Future studies are needed to examine how native species from the same mudflat as Ilyanassa obsoleta will respond to increasing temperatures under immersed and emersed conditions, allowing us to predict how the mudflat intertidal community will shift with changing global temperatures.