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Giant Kelp Unaffected by Ocean Acidification

Paper Reviewed
Fernández, P.A., Roleda, M.Y. and Hurd, C.L. 2015. Effects of ocean acidification on the photosynthetic performance, carbonic anhydrase activity and growth of the giant kelp Macrocystis pyrifera. Photosynthesis Research 124: 293-304.

Noting that "predicted changes in seawater carbonate chemistry can influence important biological and physiological processes of calcifying and non-calcifying marine organisms" and that "seaweeds are the base of the food web and major contributors to benthic primary production in coastal ecosystems," Fernández et al. (2015) designed an experiment to study the effects of declining oceanic pH on Macrocystis pyrifera, a "dominant, highly productive brown seaweed of temperate coastlines of the northern and southern Pacific."

To accomplish their objective, samples of Macrocystis were acquired from Otago Harbor, New Zealand and then grown in a laboratory for seven days under present day and predicted future atmospheric CO2 concentrations, which corresponded to seawater pH treatments of 8.05 and 7.59, respectively. Among their reported findings, the three researchers note there was no significant difference in photosynthetic rates of Macrocystis growing at either pH treatment level. Similarly, there was no significant difference in relative growth rate, although growth rates measured on days 3 and 7 averaged 28% and 17% higher, respectively, in the future pH treatment (pH of 7.59) than the present-day treatment (pH of 8.05) (see figure below).

The results of Fernández et al.'s work are encouraging in that they contrast with the seemingly never ending barrage of news stories predicting gloom and doom for marine life from ocean acidification. As demonstrated here, and in numerous additional reviews of other experiments posted on our website (found under the topics -- and sub-topics -- of Ocean Acidification and Ocean Acidification and Warming in our Subject Index), for many species, ocean acidification will be a non-problem ... and maybe even a blessing!

Posted 25 September 2015