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Ocean acidification reduces the growth of two Southern Ocean phytoplankton

Citation

Andrew, SM and Strzepek, RF and Branson, O and Ellwood, MJ, Ocean acidification reduces the growth of two Southern Ocean phytoplankton, Marine Ecology Progress Series, 682 pp. 51-64. ISSN 0171-8630 (2022) [Refereed Article]


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Copyright (2022) Inter-Research

DOI: doi:10.3354/meps13923

Abstract

Model projections for the Southern Ocean indicate that light, iron (Fe) availability, temperature and carbon dioxide (CO2) will change concurrently in the future. We investigated the physiological responses of Southern Ocean phytoplankton to multiple variables by culturing the haptophyte Phaeocystis antarctica and the diatom Chaetoceros flexuosus under various combinations of light, Fe, temperature and CO2. Using statistical models, the influence of each environmental variable was analysed for each physiological response, ultimately predicting how ‘future’ conditions (high temperature and high CO2) would influence the 2 phytoplankton species. Under future conditions, cellular chlorophyll a and carbon to nitrogen molar ratios were modelled to increase for both species in all light and Fe treatments, but at times were inconsistent with measured values. Measured and modelled values of the photochemical efficiency of photosystem II (Fv/Fm) declined in cultures of P. antarctica due to concurrent increases in temperature and CO2, under all light and Fe treatments. The trends in Fv/Fm for C. flexuosus were less clear. Our model and observations suggest that when temperature and CO2 are concurrently increased, the growth of both species remains largely unchanged. This modelling analysis reveals that high CO2 exerts a strong negative influence on the growth of both phytoplankton, and any ‘future’ increase in growth can be attributed to the positive effect of warming rather than a CO2 fertilisation effect.

Item Details

Item Type:Refereed Article
Keywords:iron, light, temperature, photosynthesis, climate change
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Biological oceanography
Objective Division:Environmental Management
Objective Group:Management of Antarctic and Southern Ocean environments
Objective Field:Antarctic and Southern Ocean oceanic processes
UTAS Author:Strzepek, RF (Dr Robert Strzepek)
ID Code:150898
Year Published:2022
Deposited By:Australian Antarctic Program Partnership
Deposited On:2022-07-04
Last Modified:2022-08-08
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