Publication Date:
2024-03-15
Description:
Relative to their surface area, estuaries make a disproportionately large contribution of dissolved organic carbon (DOC) to the global carbon cycle, but it is unknown how this will change under a future climate. As such, the response of DOC fluxes from microbially dominated unvegetated sediments to individual and combined future climate stressors of temperature change (from delta −3 to delta +5 °C compared to ambient mean temperatures) and ocean acidification (OA, 2*current CO2 partial pressure, pCO2) was investigated ex situ. Warming alone increased sediment heterotrophy, resulting in a proportional increase in sediment DOC uptake; sediments became net sinks of DOC (3.5 to 8.8 mmol C/m**2/d) at warmer temperatures (delta +3 and delta +5 °C, respectively). This temperature response changed under OA conditions, with sediments becoming more autotrophic and a greater sink of DOC (up to 4* greater than under current pCO2 conditions). This response was attributed to the stimulation of heterotrophic bacteria with the autochthonous production of labile organic matter by microphytobenthos. Extrapolating these results to the global area of unvegetated subtidal estuarine sediments, we find that the future climate of warming (delta +3 °C) and OA may decrease estuarine export of DOC by ∼ 80 % (150 Tg C/yr) and have a disproportionately large impact on the global DOC budget.
Keywords:
AIRICA analyzer (Miranda); Alkalinity, total; Alkalinity, total, standard deviation; Aragonite saturation state; Benthos; Bicarbonate ion; Bicarbonate ion, standard deviation; Bottles or small containers/Aquaria (〈20 L); Calcite saturation state; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, flux; Carbon, inorganic, dissolved, flux, standard deviation; Carbon, inorganic, dissolved, standard deviation; Carbon, organic, dissolved; Carbon, organic, dissolved, flux; Carbon, organic, dissolved, flux, standard deviation; Carbonate ion; Carbonate ion, standard deviation; Carbonate system computation flag; Carbon dioxide; Clarence_River_estuary; Coast and continental shelf; DEPTH, sediment/rock; DEPTH, water; Entire community; EXP; Experiment; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Gross primary production of oxygen; Gross primary production of oxygen, standard deviation; Laboratory experiment; Net primary production of oxygen; Net primary production of oxygen, standard deviation; Nitrogen, inorganic, dissolved; Nitrogen, inorganic, dissolved, standard deviation; OA-ICC; Ocean Acidification International Coordination Centre; Other studied parameter or process; Oxygen saturation; Partial pressure of carbon dioxide, standard deviation; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; pH, standard deviation; Potentiometric; Primary production/Photosynthesis; Production/respiration ratio; Production/respiration ratio, standard deviation; Replicates; Respiration; Respiration rate, oxygen; Respiration rate, oxygen, standard deviation; Salinity; Soft-bottom community; South Pacific; Surface area; Temperate; Temperature; Temperature, water; Temperature, water, standard deviation; Time in minutes; Time point, descriptive; Treatment; Type; Volume
Type:
Dataset
Format:
text/tab-separated-values, 2737 data points
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