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Streamed live on Feb 25, 2016
Despite numerous successful adaptations to an aquatic existence, seagrasses have high light requirements that make them vulnerable to anthropogenic disturbance. We explored the response of Chesapeake Bay eelgrass to increased CO2 availability within the context of a warming coastal ocean using a combination of manipulative experiments, physiological/biochemical investigations and mathematical modeling. Eelgrass survival, shoot size, growth rate, vegetative shoot propagation, and flowering shoot production responded in a positive, logarithmic fashion to CO2 enrichment, despite prolonged summertime exposure to water temperatures up to 30° C that typically result in shoot die-back. Rising CO2(aq) appears to increase the high temperature tolerance of plants by improving the Q10 response of photosynthesis relative to respiration, thereby maintaining positive carbon balance that facilitates higher growth rates and improved survival of vegetative shoots at high temperature. The response of Chesapeake Bay eelgrass growing near the southern limit of its distribution on the Atlantic coast is providing predictive insight into how climate change may alter the geographic distribution of this critically important species in other coastal environments that may be subjected to multiple stressors linked to climate change.
Richard C. Zimmerman is a biological oceanographer with over 30 years experience in experimental plant physiology, primary productivity of coastal ecosystems, aquatic optics and instrument development for ocean observation. He received B.S., M.S. and Ph.D. degrees in Biology from the University of Southern California. Current research interests include the combined impacts of climate change and water quality on submerged aquatic vegetation and estuarine phytoplankton, and the development of compact lidar systems for remotely observing the vertical structure of the surface ocean.