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Biogeosciences An interactive open-access journal of the European Geosciences Union
Biogeosciences, 12, 4235-4244, 2015
https://doi.org/10.5194/bg-12-4235-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
20 Jul 2015
Resilience to temperature and pH changes in a future climate change scenario in six strains of the polar diatom Fragilariopsis cylindrus
M. Pančić1,2, P. J. Hansen3, A. Tammilehto1, and N. Lundholm1 1Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark
2National Institute of Aquatic Resources, DTU Aqua, Section for Marine Ecology and Oceanography, Technical University of Denmark, Charlottenlund, Denmark
3Marine Biological Section, University of Copenhagen, Helsingør, Denmark
Abstract. The effects of ocean acidification and increased temperature on physiology of six strains of the polar diatom Fragilariopsis cylindrus from Greenland were investigated. Experiments were performed under manipulated pH levels (8.0, 7.7, 7.4, and 7.1) and different temperatures (1, 5, and 8 °C) to simulate changes from present to plausible future levels. Each of the 12 scenarios was run for 7 days, and a significant interaction between temperature and pH on growth was detected. By combining increased temperature and acidification, the two factors counterbalanced each other, and therefore no effect on the growth rates was found. However, the growth rates increased with elevated temperatures by ~ 20–50 % depending on the strain. In addition, a general negative effect of increasing acidification on growth was observed. At pH 7.7 and 7.4, the growth response varied considerably among strains. However, a more uniform response was detected at pH 7.1 with most of the strains exhibiting reduced growth rates by 20–37 % compared to pH 8.0. It should be emphasized that a significant interaction between temperature and pH was found, meaning that the combination of the two parameters affected growth differently than when considering one at a time. Based on these results, we anticipate that the polar diatom F. cylindrus will be unaffected by changes in temperature and pH within the range expected by the end of the century. In each simulated scenario, the variation in growth rates among the strains was larger than the variation observed due to the whole range of changes in either pH or temperature. Climate change may therefore not affect the species as such, but may lead to changes in the population structure of the species, with the strains exhibiting high phenotypic plasticity, in terms of temperature and pH tolerance towards future conditions, dominating the population.

Citation: Pančić, M., Hansen, P. J., Tammilehto, A., and Lundholm, N.: Resilience to temperature and pH changes in a future climate change scenario in six strains of the polar diatom Fragilariopsis cylindrus, Biogeosciences, 12, 4235-4244, https://doi.org/10.5194/bg-12-4235-2015, 2015.
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Short summary
Climate change may not affect phytoplankton species as such, but may lead to changes in population structure of a species, with strains exhibiting high phenotypic plasticity dominating the population. Simulated climate scenarios showed that combined effects of increased temperature and acidification counterbalanced each other in the ecologically important model organism Fragilariopsis cylindrus. The variation among strains was larger than the variation observed due to the changes in parameters.
Climate change may not affect phytoplankton species as such, but may lead to changes in...
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