Collaborative Research: Impact of Climate Warming and Ocean Carbonation on Eelgrass (Zostera marina L.)

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Intellectual Merit: The past few decades have accumulated mounting evidence of profound anthropogenic effects on fundamental biogeochemical processes across the planet, especially in coastal environments that support a diverse array of highly productive ecosystems including coral reefs, seagrass meadows, and estuaries. The ecological significance of seagrasses is largely due to the remarkable degree of adaptation they exhibit to a submerged aquatic existence. Despite numerous successful adaptations, however, seagrasses have high light requirements that make them vulnerable to anthropogenic disturbances. The paradoxical vulnerability results largely from their high reliance on dissolved aqueous CO2 for photosynthesis. The potential for rising atmospheric CO2 concentrations to have significant warming impacts on the global climate has long been recognized, but the potential impacts of the "other CO2 problem", also known as ocean acidification, have only recently begun to be appreciated. As with other impacts of climate change, the increased concentrations of dissolved aqueous CO2 [CO2 (aq)] in the oceans of the world will elicit both negative and positive responses among organisms, ultimately potentiating ecological losers and winners. This project will explore the response of eelgrass to increased CO2 (aq) within the context of a warming coastal ocean using a combination of manipulative experiments, physiological/biochemical investigations and mathematical modeling. The investigators hypothesize that rising CO2(aq) will increase the high temperature tolerance of plants by improving the Q10 response of photosynthesis relative to respiration, thereby leading to higher growth rates, improved survival of vegetative shoots at high temperature, and even flowering output and seed production. This project will investigate the key relationships between environmental parameters that have both negative (ocean warming) and positive (ocean carbonation) impacts on the light requirements and dynamics of carbon balance in these critically important marine angiosperms. By focusing on Chesapeake populations growing near the southern limit of eelgrass distribution on the Atlantic coast, the investigators will gain 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 less temperature stress but similar levels of ocean carbonation.Broader Impacts: This work will provide training in plant physiology and biochemistry to the co-PI, Dr. Victoria Hill and will support the dissertation research of at least two graduate students over the course of the 4-year study. Collaboration with the Virginia Aquarium and Marine Science Center will facilitate the development of educational interpretation and programming from this project that will be specifically targeted to the 650,000 to 700,000 people that visit the Aquarium each year.