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Effects of ocean acidification on the photosynthetic performance, carbonic anhydrase activity and growth of the giant kelp Macrocystis pyrifera


Fernandez, PA and Roleda, MY and Hurd, CL, Effects of ocean acidification on the photosynthetic performance, carbonic anhydrase activity and growth of the giant kelp Macrocystis pyrifera, Photosynthesis Research, 124, (3) pp. 293-304. ISSN 0166-8595 (2015) [Refereed Article]

Copyright Statement

Copyright 2015 Springer Science+Business Media Dordrecht

DOI: doi:10.1007/s11120-015-0138-5


Under ocean acidification (OA), the 200 % increase in CO2(aq) and the reduction of pH by 0.3-0.4 units are predicted to affect the carbon physiology and growth of macroalgae. Here we examined how the physiology of the giant kelp Macrocystis pyrifera is affected by elevated pCO2/low pH. Growth and photosynthetic rates, external and internal carbonic anhydrase (CA) activity, HCO3 - versus CO2 use were determined over a 7-day incubation at ambient pCO2 400 ľatm/pH 8.00 and a future OA treatment of pCO2 1200 ľatm/pH 7.59. Neither the photosynthetic nor growth rates were changed by elevated CO2 supply in the OA treatment. These results were explained by the greater use of HCO3 - compared to CO2 as an inorganic carbon (Ci) source to support photosynthesis. Macrocystis is a mixed HCO3 - and CO2 user that exhibits two effective mechanisms for HCO3 - utilization; as predicted for species that possess carbon-concentrating mechanisms (CCMs), photosynthesis was not substantially affected by elevated pCO2. The internal CA activity was also unaffected by OA, and it remained high and active throughout the experiment; this suggests that HCO3 - uptake via an anion exchange protein was not affected by OA. Our results suggest that photosynthetic Ci uptake and growth of Macrocystis will not be affected by elevated pCO2/low pH predicted for the future, but the combined effects with other environmental factors like temperature and nutrient availability could change the physiological response of Macrocystis to OA. Therefore, further studies will be important to elucidate how this species might respond to the global environmental change predicted for the ocean.

Item Details

Item Type:Refereed Article
Keywords:Macrocystis, ocean acidification, kelp, climate change, seaweed, physiological ecology, carbon dioxide, photosynthesis
Research Division:Environmental Sciences
Research Group:Climate change impacts and adaptation
Research Field:Ecological impacts of climate change and ecological adaptation
Objective Division:Environmental Policy, Climate Change and Natural Hazards
Objective Group:Adaptation to climate change
Objective Field:Ecosystem adaptation to climate change
UTAS Author:Hurd, CL (Professor Catriona Hurd)
ID Code:100172
Year Published:2015
Web of Science® Times Cited:69
Deposited By:IMAS Research and Education Centre
Deposited On:2015-05-06
Last Modified:2017-10-31

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