Ocean acidification and the loss of phenolic substances in marine plants

• Main Authors: Arnold, Thomas, Mealey, Christopher, Leahey, Hannah, Miller, A Whitman, Hall-Spencer, Jason M, Milazzo, Marco, Maers, Kelly
• Format: Dataset
• Language: English
• Published: PANGAEA 2012
• Subjects: Acetovanillone; standard error; Aeolian_archipelago; Alkalinity; total; Aragonite saturation state; Benthos; Bicarbonate ion; Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; CO2 vent; Coast and continental shelf; Coumaric acid; Cymodocea nodosa; Description; Distance; Event label; EXP; Experiment; Ferulic acid; Field experiment; Field observation; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Gallic acid; Identification; Immunology/Self-protection; Mediterranean Sea; Mediterranean Sea Acidification in a Changing Climate; MedSeA; Mesocosm or benthocosm; North Atlantic; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.829532; https://doi.org/10.1594/PANGAEA.829532

Rising atmospheric CO2 often triggers the production of plant phenolics, including many that serve as herbivore deterrents, digestion reducers, antimicrobials, or ultraviolet sunscreens. Such responses are predicted by popular models of plant defense, especially resource availability models which link carbon availability to phenolic biosynthesis. CO2 availability is also increasing in the oceans, where anthropogenic emissions cause ocean acidification, decreasing seawater pH and shifting the carbonate system towards further CO2 enrichment. Such conditions tend to increase seagrass productivity but may also increase rates of grazing on these marine plants. Here we show that high CO2 / low pH conditions of OA decrease, rather than increase, concentrations of phenolic protective substances in seagrasses and eurysaline marine plants. We observed a loss of simple and polymeric phenolics in the seagrass Cymodocea nodosa near a volcanic CO2 vent on the Island of Vulcano, Italy, where pH values decreased from 8.1 to 7.3 and pCO2 concentrations increased ten-fold. We observed similar responses in two estuarine species, Ruppia maritima and Potamogeton perfoliatus, in in situ Free-Ocean-Carbon-Enrichment experiments conducted in tributaries of the Chesapeake Bay, USA. These responses are strikingly different than those exhibited by terrestrial plants. The loss of phenolic substances may explain the higher-than-usual rates of grazing observed near undersea CO2 vents and suggests that ocean acidification may alter coastal carbon fluxes by affecting rates of decomposition, grazing, and disease. Our observations temper recent predictions that seagrasses would necessarily be "winners" in a high CO2 world.