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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
Citation
Fernandez, PA and Roleda, MY and Leal, PP and Hurd, CL, 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, Physiologia Plantarum, 159, (1) pp. 107-119. ISSN 0031-9317 (2017) [Refereed Article]
Copyright Statement
Copyright 2016 Scandinavian Plant Physiology Society
Abstract
Ocean acidification (OA), the ongoing decline in seawater pH, is predicted to have wide-ranging effects on marine organisms and ecosystems. For seaweeds, the pH at the thallus surface, within the diffusion boundary layer (DBL), is one of the factors controlling their response to OA. Surface pH is controlled by both the pH of the bulk seawater and by the seaweeds’ metabolism: photosynthesis and respiration increase and decrease pH within the DBL (pHDBL), respectively. However, other metabolic processes, especially the uptake of inorganic nitrogen (Ni; NO3− and NH4+) may also affect the pHDBL. Using Macrocystis pyrifera, we hypothesized that (1) NO3− uptake will increase the pHDBL, whereas NH4+ uptake will decrease it, (2) if NO3− is cotransported with H+, increases in pHDBL would be greater under an OA treatment (pH = 7.65) than under an ambient treatment (pH = 8.00), and (3) decreases in pHDBL will be smaller at pH 7.65 than at pH 8.00, as higher external [H+] might affect the strength of the diffusion gradient. Overall, Ni source did not affect the pHDBL. However, increases in pHDBL were greater at pH 7.65 than at pH 8.00. CO2 uptake was higher at pH 7.65 than at pH 8.00, whereas HCO3− uptake was unaffected by pH. Photosynthesis and respiration control pHDBL rather than Ni uptake. We suggest that under future OA, Macrocystis pyrifera will metabolically modify its surface microenvironment such that the physiological processes of photosynthesis and Ni uptake will not be affected by a reduced pH.
Item Details
| Item Type: | Refereed Article |
|---|---|
| Keywords: | Macrocystis, kelp, ocean acidification, nitrogen, climate change |
| Research Division: | Biological Sciences |
| Research Group: | Plant biology |
| Research Field: | Phycology (incl. marine grasses) |
| Objective Division: | Environmental Policy, Climate Change and Natural Hazards |
| Objective Group: | Adaptation to climate change |
| Objective Field: | Ecosystem adaptation to climate change |
| UTAS Author: | Fernandez, PA (Ms Pamela Fernandez Subiabre) |
| UTAS Author: | Leal, PP (Mr Pablo Leal Sandoval) |
| UTAS Author: | Hurd, CL (Professor Catriona Hurd) |
| ID Code: | 112297 |
| Year Published: | 2017 |
| Web of Science® Times Cited: | 10 |
| Deposited By: | Ecology and Biodiversity |
| Deposited On: | 2016-11-03 |
| Last Modified: | 2018-08-28 |
| Downloads: | 0 |
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