This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
Marine intertidal zone organisms have evolved elevated thermal tolerance limits in response to thermal stress associated with times that low tide coincides with heat waves. Climate-change projected increases in the frequency and severity of such events are hypothesized to have an impact on these organisms due to the energetic expenditure of maintaining elevated heat tolerance. That elevated heat tolerance has an energetic cost is a long-standing assumption in thermal physiology but the actual costs have not been quantified. This project will compare thermal tolerance across life-history stages (embryonic, larval planktonic, juvenile and adult) in species of closely related porcelain crabs from temperate and tropical intertidal and subtidal habitats that experience a wide gradient in maximal habitat temperature. In species with different thermal tolerances, basal metabolic rates, temperature sensitivity of metabolism and metabolic enzymes, energy storage, and growth rates will be examined. Larvae differ in thermal habitat from the other stages since the larvae are planktonic and not subjected to thermal extremes of the intertidal zone. Larvae are expected to avoid the physiological costs associated with elevated thermal tolerance, and the largest difference between larval and other life history stage thermal tolerance is expected in the most heat tolerant species. From the difference between larval and adult metabolism the actual energetic cost of elevated thermal tolerance will be quantified. Quantification of those costs will be useful for assessing how climate change increases in thermal stress will impact energetics of marine intertidal zone invertebrates across their distribution in the natural environment.
The broader impacts of this project include education of a postdoctoral researcher for one year, a MS graduate student for two years, and undergraduate research assistants recruited through the SFSU BREED REU program as well as an Animal Physiology Laboratory course taught by the PI.
