Meeting Abstract
In addition to higher average temperatures, global climate change is also resulting in higher temperature variability, increasing the risk that species’ tolerance limits will be exceeded. Our study was designed to determine how prior thermal history and the intensity of an acute high temperature challenge might affect post-stress photosynthetic performance of microalgae on rocky shores. We manipulated temperature variability on artificial substrata in the mid-intertidal zone, allowing microalgae to settle under low, natural, or high variation for at least one month. We then measured community-level net photosynthetic rate (NPR) for each experimental plate under benign conditions with a LICOR LX-1600, before and after exposure to one of five peak temperatures (18, 24, 28, 32, or 36 °C) during a 4.5-hour simulated low tide. The more extreme the acute temperature challenge, the more negative the effect on post-exposure NPR. More surprisingly, microalgae grown on low variation plates in the field were twice as vulnerable as microalgae on normal and high variability plates. We are using scanning electron microscopy (SEM) and high-performance liquid chromatography (HPLC) to analyze changes in the identity and relative abundances of microalgal taxa for indications of variation in microalgal functional group composition and diversity.
