Seawater carbonate chemistry and concentration boundary layers around complex assemblages of macroalgae in a laboratory experiment, supplement to: Cornwall, Christopher Edward; Hepburn, Christopher D; Pilditch, Conrad A; Hurd, Catriona L (2013): Concentration boundary layers around complex assemblages of macroalgae: Implications for the effects of ocean acidification on understory coralline algae. Limnology and Oceanography, 58(1), 121-130

• Main Authors: Cornwall, Christopher Edward, Hepburn, Christopher D, Pilditch, Conrad A, Hurd, Catriona L
• Format: Dataset
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 2013
• Subjects: Arthrocardia corymbosa; Benthos; Coast and continental shelf; Containers and aquaria 20-1000 L or < 1 m**2; Laboratory experiment; Light; Macroalgae; Other; Other metabolic rates; Plantae; Rhodophyta; Single species; South Pacific; Temperate; Species; Identification; Distance; Irradiance; Treatment; Flow velocity, water; pH; pH, standard deviation; pH, standard error; Oxygen; Oxygen, standard deviation; Oxygen, standard error; Concentration boundary layer, thickness; Concentration boundary layer, thickness, standard deviation; Concentration boundary layer, thickness, standard error; Salinity; Salinity, standard error; Temperature, water; Temperature, water, 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; Alkalinity, total; Alkalinity, total, standard error; Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard error; Carbon dioxide; Carbon dioxide, standard error; Bicarbonate ion; Bicarbonate ion, standard error; Carbonate ion; Carbonate ion, standard error; Carbonate system computation flag; Fugacity of carbon dioxide water at sea surface temperature wet air; Aragonite saturation state; Calcite saturation state; Experiment; Potentiometric; Microoptode; Calculated; Potentiometric titration; Calculated using seacarb after Nisumaa et al. 2010; Ocean Acidification International Coordination Centre OA-ICC; Cornwall; Hurd; Pacific; Ocean acidification
• Online Access: https://dx.doi.org/10.1594/pangaea.823580; https://doi.pangaea.de/10.1594/PANGAEA.823580

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. : In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Lavigne and Gattuso, 2011) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI). The date of carbonate chemistry calculation by seacarb is 2013-11-29.