PARENT SESSION
Oral Session 10: Physiology I: Temperature, Light, and Growth.
Presiding: C Knight
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room C 123.

Thermal acclimatization of Asparagopsis taxiformis from different biogeographic regions.

Padilla-Gamino, Jacqueline^*,1, Carpenter, Robert¹, ¹ Department of Biology, Northridge, CA 91330-8303

ABSTRACT- As climate changes, temperature shifts may be one of the most important factors that allow non-indigenous species to become established in new locations. In order to predict the propensity for some but not other species to become invasive, we need to understand the biology of introduced species, and the physiological basis of acclimation. This investigation addresses how temperature influences the physiological performance of Asparagopsis taxiformisin two of the most diverse and productive marine ecosystems (coral reefs and kelp forests). The experiments were performed at Santa Catalina Island (California) associated with temperature ranges of 14-21°C and Kaneohe Bay (Hawaii) associated with temperature ranges of 24-28°C. Photosynthetic and respiration rates (oxygen production/consumption), parameters from ETR-PFD curves (ETRmax, R, alpha, Ic and Ik) and photosynthetic pigment content were compared between locations to observe their temperature acclimation responses. The results indicate that maximum photosynthetic rate was more affected by temperature for Asparagopsisin Hawaii. Individuals from California show a broader temperature optimum for photosynthesis. Additionally, chlorophyll fluorescence yield from dark-adapted samples differed with California individuals showing maximum yields at 15°C while individuals from Hawaii had maximum yields at 25°C. Measurements will continue in the winter to compare laboratory acclimation and seasonal acclimatization to observe the phenotypic plasticity of thermal tolerance limits at different temporal scales.

Key words: red algae, photosynthesis, physiology, thermal stress