FN Archimer Export Format PT J TI Dynamics of benthic metabolism, O2, and pCO2 in a temperate seagrass meadow BT AF Berg, Peter Delgard, Marie Lise Polsenaere, Pierre McGlathery, Karen J. Doney, Scott C. Berger, Amelie C. AS 1:1;2:1;3:2;4:1;5:1;6:1; FF 1:;2:;3:PDG-ODE-LITTORAL-LERPC;4:;5:;6:; C1 Department of Environmental Sciences, University of Virginia, Charlottesville Virginia, usa Resources and Environment Laboratory, IFREMER, L'Houmeau, France C2 UNIV VIRGINIA, USA IFREMER, FRANCE SI LA ROCHELLE SE PDG-ODE-LITTORAL-LERPC IN WOS Ifremer UPR copubli-int-hors-europe IF 3.778 TC 37 UR https://archimer.ifremer.fr/doc/00504/61565/65490.pdf LA English DT Article AB Seagrass meadows play an important role in “blue carbon” sequestration and storage, but their dynamic metabolism is not fully understood. In a dense Zostera marina meadow, we measured benthic O2 fluxes by aquatic eddy covariance, water column concentrations of O2, and partial pressures of CO2 (pCO2) over 21 full days during peak growing season in April and June. Seagrass metabolism, derived from the O2 flux, varied markedly between the 2 months as biomass accumulated and water temperature increased from 16°C to 28°C, triggering a twofold increase in respiration and a trophic shift of the seagrass meadow from being a carbon sink to a carbon source. Seagrass metabolism was the major driver of diurnal fluctuations in water column O2 concentration and pCO2, ranging from 173 to 377 μmol L−1 and 193 to 859 ppmv, respectively. This 4.5‐fold variation in pCO2 was observed despite buffering by the carbonate system. Hysteresis in diurnal water column pCO2 vs. O2 concentration was attributed to storage of O2 and CO2 in seagrass tissue, air–water exchange of O2 and CO2, and CO2 storage in surface sediment. There was a ~ 1:1 mol‐to‐mol stoichiometric relationship between diurnal fluctuations in concentrations of O2 and dissolved inorganic carbon. Our measurements showed no stimulation of photosynthesis at high CO2 and low O2 concentrations, even though CO2 reached levels used in IPCC ocean acidification scenarios. This field study does not support the notion that seagrass meadows may be “winners” in future oceans with elevated CO2 concentrations and more frequent temperature extremes. PY 2019 PD NOV SO Limnology And Oceanography SN 0024-3590 PU Wiley VL 64 IS 6 UT 000495506200019 BP 2586 EP 2604 DI 10.1002/lno.11236 ID 61565 ER EF