Project: Ocean Acidification: Understanding the Impact of CO2 and Temperature on the Physiological, Genetic, and Epigenetic Response of a Model Sea Anemone System with Different Symbionts

The projected rise in carbon dioxide (CO2) in the atmosphere is considered a primary threat to marine systems throughout the world due to both ocean acidification and rising ocean temperatures. Coral reefs are very sensitive to these projected changes in the earth's climate, with continued losses in growth as well as disruption (also known as bleaching) in the symbiotic relationship between the algae (Symbiodinium) living within a diversity of host animals, including stony corals, soft corals and sea anemones. While much information has been gleaned as to how acidification may affect stony corals, considerably less is known about the interactive effects of acidification and temperature to other symbiotic anthozoans.

To this end, this proposal will investigate the long-term impacts of elevated CO2 and temperature on the model sea anemone, Aiptasia pallida, while harboring four different genotypes of Symbiodinium. The primary goals of this project are (1) to determine the sensitivity and capacity for acclimation in molecular and physiological processes while exposed to elevated CO2 and temperature, and (2) to assess the degree to which acclimated adult animals may confer (or transfer) an imprinted physiological characteristic to the next generation of asexual offspring. A series of long-term experiments will be conducted with each animal/algal combination (holobiont) in order to collect initial (3 month) stress markers and genomic data and then follow animal response and asexual reproduction through several generations for one year. The possibility for enhanced resilience or acclimation will be measured by tracking the recovery of each holobiont, followed by repeated exposure to elevated temperature while held in high CO2. This project will tease apart fine scale mechanisms of stress, acclimation, or amelioration that may vary as a function of algal genotype and host animal response, and the degree to which environmental imprinting may pre-acclimate propagules. Project results will provide information regarding how future acidification and warming will affect cnidarian-algal symbioses, and the fundamental profile of their flexibility in stress response processes across organismal, metabolic, genomic and epigenetic scales.