Publication Date:
2024-03-15
Description:
Metabolic processes have the potential to modulate the effects of ocean acidification (OA) in nearshore macroalgal beds. We investigated whether natural mixed assemblages of the articulate coralline macroalgae Arthrocardia corymbosa and understory crustose coralline algae (CCA) altered pH and O2 concentrations within and immediately above their canopies. In a unidirectional flume, we tested the effect of water velocity (0-0.1 m/s), bulk seawater pH (ambient pH 8.05, and pH 7.65), and irradiance (photosynthetically saturating light and darkness) on pH and O2 concentration gradients, and the derived concentration boundary layer (CBL) thickness. At bulk seawater pH 7.65 and slow velocities (0 and 0.015 m/s), pH at the CCA surface increased to 7.90-8.00 in the light. Although these manipulations were short term, this indicates a potential daytime buffering capacity that could alleviate the effects of OA. Photosynthetic activity also increased O2 concentrations at the surface of the CCA. However, this moderating capacity was flow dependent; the CBL thickness decreased from an average of 26.8 mm from the CCA surface at 0.015 m/s to 4.1 mm at 0.04 m/s. The reverse trends occurred in the dark, with respiration causing pH and O2 concentrations to decrease at the CCA surface. At all flow velocities the CBL thicknesses (up to 68 mm) were much greater than those previously published, indicating that the presence of canopies can alter the CBL substantially. In situ, the height of macroalgal canopies can be an order of magnitude larger than those used here, indicating that the degree of buffering to OA will be context dependent.
Keywords:
Alkalinity, total; Alkalinity, total, standard error; Aragonite saturation state; Arthrocardia corymbosa; Benthos; Bicarbonate ion; Bicarbonate ion, standard error; Calcite saturation state; Calculated; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard error; Carbonate ion; Carbonate ion, standard error; Carbonate system computation flag; Carbon dioxide; Carbon dioxide, standard error; Coast and continental shelf; Concentration boundary layer, thickness; Concentration boundary layer, thickness, standard deviation; Concentration boundary layer, thickness, standard error; Containers and aquaria (20-1000 L or 〈 1 m**2); Distance; EXP; Experiment; Flow velocity, water; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Identification; Irradiance; Laboratory experiment; Light; Macroalgae; Microoptode; OA-ICC; Ocean Acidification International Coordination Centre; Other; Other metabolic rates; Oxygen; Oxygen, standard deviation; Oxygen, standard error; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Partial pressure of carbon dioxide (water) at sea surface temperature (wet air), standard error; pH; pH, standard deviation; pH, standard error; Plantae; Potentiometric; Potentiometric titration; Rhodophyta; Salinity; Salinity, standard error; Single species; South Pacific; Species; Temperate; Temperature, water; Temperature, water, standard error; Treatment; Warrington
Type:
Dataset
Format:
text/tab-separated-values, 7360 data points
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