AME 70:1-15 (2013)  -  DOI: https://doi.org/10.3354/ame01633

Effect of ocean acidification on bacterial abundance, activity and diversity in the Ross Sea, Antarctica

Elizabeth W. Maas1,*, Cliff S. Law1, Julie A. Hall1, Stu Pickmere2, Kim I. Currie3, F. H. Chang1, K. Matt Voyles1, Dianna Caird1

1National Institute of Water and Atmospheric Research, Private Bag 14901, Wellington, New Zealand
2National Institute of Water and Atmospheric Research, PO Box 11-115, Hamilton, New Zealand
3National Institute of Water and Atmospheric Research, Centre for Chemical and Physical Oceanography, University of Otago, Dunedin, New Zealand

ABSTRACT: Three ocean acidification experiments were conducted on water from the same location in the Ross Sea, Southern Ocean, to ascertain how surface-water mixed populations, including the microbial community, would respond to changes in pH (pH 7.80 and 7.65). Bacterial extracellular enzymes, abundances, thymidine uptake rate, the diversity of the active fraction of the bacterial community and phytoplankton diversity were measured in response to changes in pH. Bacterial abundance increased at lower pH, and the active fraction of the bacteria decreased, concurrently becoming less diverse within 8 d. However, as the active fraction of the bacterial community evolved, changes in bacterial extracellular enzyme rates occurred, with phosphatase, β-glucosidase and lipase activity increasing up to 2-fold in the acidified incubations. These results suggest that carbohydrates and lipids may be hydrolysed faster with more rapid regeneration of nutrients at lower pH. The changes observed in our experiments indicate that the bacteria in the Ross Sea adapt quickly to lower pH but that bacterial diversity will be lost. However, this loss of diversity did not adversely affect bacterial activity and in fact enhanced their ability to break down carbohydrates and lipids and recycle phosphate. These changes will alter the rate of carbon and phosphate regeneration, potentially accelerating decomposition in surface waters and short-circuiting the biological pump.


KEY WORDS: Ocean acidification · Bacterial abundance · Extracellular enzymes · Bacterial diversity · RNA-T-RFLP · Ross Sea


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Cite this article as: Maas EW, Law CS, Hall JA, Pickmere S and others (2013) Effect of ocean acidification on bacterial abundance, activity and diversity in the Ross Sea, Antarctica. Aquat Microb Ecol 70:1-15. https://doi.org/10.3354/ame01633

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