Highly productive macrophytes produce diurnal and seasonal cycles in CO2 concentrations modulated by metabolic activity, which cause discrepancies between pH in the bulk water and near seaweed blades, especially when entering the diffusion boundary layer (DBL). Calcifying epiphytic organisms living in this environment are therefore exposed to a different pH environment than that of the water column. To evaluate the actual pH environment on blade surfaces, we measured the thickness of the DBL and pH gradients within it for six subarctic macrophytes: Fucus vesiculosus, Ascophyllum nodosum, Ulva lactuca, Zostera marina, Saccharina longicruris, and Agarum clathratum. We measured pH under laboratory conditions at ambient temperatures (2–3 °C) and slow, stable flow over the blade surface at five light intensities (dark, 30, 50, 100 and 200 µmol photons m−2 s−1). Boundary layer thickness ranged between 511 and 1632 µm, while the maximum difference in pH (∆pH) between the blade surface and the water column ranged between 0.4 ± 0.14 (average ± SE; Zostera) and 1.2 ± 0.13 (average ± SE; Ulva) pH units. These differences in pH are larger than predictions for pH changes in the bulk water by the end of the century. A simple quadratic model best described the relationship between light intensity and maximum ∆pH, pointing at relatively low optimum PAR of between 28 and 139 µmol photons m−2 s−1 to reach maximum ∆pH. Elevated pH at the blade surface may provide chemical “refugia” for calcifying epiphytic organisms, especially during summer at higher latitudes where photoperiods are long.
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Cornwall CE, Pilditch CA, Hepburn CD, Hurd CL (2015) Canopy macroalgae influence understorey corallines’ metabolic control of near-surface pH and oxygen concentration. Mar Ecol Prog Ser 525:81–95
Dong B, Han R, Wang G (2014) O2, pH, and redox potential microprofiles around Potamogeton malaianus measured using microsensors. PLoS ONE 9:e101825
Duarte CM, Hendriks IE, Moore TS, Olsen YS, Steckbauer A, Ramajo L, Carstensen J, Trotter JA, McCulloch M (2013) Is ocean acidification an open-ocean syndrome? Understanding anthropogenic impacts on seawater pH. Estuar Coast 36:221–236
Enriquez S, Rodriguez Roman A, Enríquez S, Rodríguez Román A (2006) Effect of water flow on the photosynthesis of three marine macrophytes from a fringing-reef lagoon. Mar Ecol Prog Ser 323:119–132
Fabry VJ, McClintock JB, Mathis JT, Grebmeier JM (2009) Ocean acidification at high latitudes: the bellweather. Oceanography 22:160–171
Fernández PA, Roleda MY, Leal PP, Hurd CL (2017) Seawater pH, and not inorganic nitrogen source, affects pH at the blade surface of Macrocystis pyrifera: Implications for responses of the giant kelp to future oceanic conditions. Physiol Plant 159:107–119
Gaylord B et al (2007) Spatial patterns of flow and their modification within and around a giant kelp forest. Limnol Oceanogr 52:1838–1852
Hansen L (1998) The intertidal macrofauna and macroalgae at five Arctic localities (Disko, West Greenland). The 1998 Danish-German Excursion to Disko Island, West Greenland, pp 92–109
Hendriks IE, Olsen YS, Ramajo L, Basso L, Steckbauer A, Moore TS, Howard J, Duarte CM (2014) Photosynthetic activity buffers ocean acidification in seagrass meadows. Biogeosciences 11:333–346
Hofmann GE et al (2011) High-frequency dynamics of ocean pH: a multi-ecosystem comparison. PLoS ONE 6:e28983
Høgslund S, Sejr MK, Wiktor J, Blicher ME, Wegeberg S (2014) Intertidal community composition along rocky shores in South-west Greenland: a quantitative approach. Polar Biol 37:1549–1561
Hurd CL (2000) Water motion, marine macroalgal physiology, and production. J Phycol 36:453–472
Hurd CL (2015) Slow-flow habitats as refugia for coastal calcifiers from ocean acidification. J Phycol 51:599–605
Hurd CL, Pilditch CA (2011) Flow-induced morphological variations affect diffusion boundary-layer thickness of Macrocystis pyrifera (Heterokontophyta, Laminariales). J Phycol 47:341–351
Hurd C et al (2009) Testing the effects of ocean acidification on algal metabolism: considerations for experimental designs. J Phycol 45:1236–1251
Hurd CL et al (2011) Metabolically induced pH fluctuations by some coastal calcifiers exceed projected 22nd century ocean acidification: a mechanism for differential susceptibility? Global Change Biol 17:3254–3262
Jones IJ, Eaton JW, Hardwick K (2000) The influence of periphyton on boundary layer conditions: a pH microelectrode investigation. Aq Bot 67:191–206
Kaandorp JA, Kübler JE (2001) The algorithmic beauty of seaweeds, sponges and corals. Springer Science & Business Media, Berlin
Krause-Jensen D, Duarte CM, Hendriks IE, Meire L, Blicher ME, Marba N, Sejr MK (2015) Macroalgae contribute to nested mosaics of pH variability in a subarctic fjord. Biogeosciences 12:4895–4911
Krause-Jensen D, Marba N, Sanz-Martin M, Hendriks IE, Thyrring J, Carstensen J, Sejr MK, Duarte CM (2016) Long photoperiods sustain high pH in Arctic kelp forests. Sci Adv 2:e1501938. doi:10.1126/sciadv.1501938
Mercado J, Gordillo F (2011) Inorganic carbon acquisition in algal communities: are the laboratory data relevant to the natural ecosystems? Photosynth Res 109:257–267
Olesen B, Krause-Jensen D, Marbà N, Christensen PB (2015) Eelgrass Zostera marina in subarctic Greenland: dense meadows with slow biomass turnover in cold waters. Mar Ecol Progr Ser 518:107–121
Pettit LR, Smart CW, Hart MB, Milazzo M, Hall-Spencer J (2015) Seaweed fails to prevent ocean acidification impact on foraminifera along a shallow-water CO2 gradient. Ecol Evol 5:1784–1793
R Core Team (2013) R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. http://www.R-project.org/
Sharon Y, Levitan O, Spungin D, Berman-Frank I, Beer S (2011) Photoacclimation of the seagrass Halophila stipulacea to the dim irradiance at its 48-meter depth limit. Limnol Oceanogr 56:357–362
Vogel S (1994) Life in moving fluids, 2nd edn. Princeton University Press, New Jersey
Wahl M, Saderne V, Sawall Y (2015) How good are we at assessing the impact of ocean acidification in coastal systems? Limitations, omissions and strengths of commonly used experimental approaches with special emphasis on the neglected role of fluctuations. Mar Freshwater Res 67:25–36
This study was funded by the Danish Environmental Protection Agency within the Danish Cooperation for Environment in the Arctic (DANCEA).
A correction to this article is available online at https://doi.org/10.1007/s00300-017-2214-0.
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Hendriks, I.E., Duarte, C.M., Marbà, N. et al. pH gradients in the diffusive boundary layer of subarctic macrophytes. Polar Biol 40, 2343–2348 (2017). https://doi.org/10.1007/s00300-017-2143-y
- Diffusive boundary layer
- pH gradients
- Subarctic macrophytes