Long-term acclimation to elevated pCO2 alters carbon metabolism and reduces growth in the Antarctic diatom Nitzschia lecointei.
Increasing atmospheric CO2 levels are driving changes in the seawater carbonate system, resulting in higher pCO2 and reduced pH (ocean acidification). Many studies on marine organisms have focused on short-term physiological responses to increased pCO2, and few on slow-growing polar organisms with a relative low adaptation potential. In order to recognize the consequences of climate change in biological systems, acclimation and adaptation to new environments are crucial to address. In this study, physiological responses to long-term acclimation (194 days, approx. 60 asexual generations) of three pCO2 levels (280, 390 and 960 µatm) were investigated in the psychrophilic sea ice diatom Nitzschia lecointei. After 147 days, a small reduction in growth was detected at 960 µatm pCO2. Previous short-term experiments have failed to detect altered growth in N. lecointei at high pCO2, which illustrates the importance of experimental duration in studies of climate change. In addition, carbon metabolism was significantly affected by the long-term treatments, resulting in higher cellular release of dissolved organic carbon (DOC). In turn, the release of labile organic carbon stimulated bacterial productivity in this system. We conclude that long-term acclimation to ocean acidification is important for N. lecointei and that carbon overconsumption and DOC exudation may increase in a high-CO2 world.
Department of Biological and Environmental Sciences, University of Gothenburg, Göteborg, Sweden anders.torstensson@bioenv.gu.se.
Anders
A
Torstensson
Department of Biological and Environmental Sciences, University of Gothenburg, Göteborg, Sweden.
Mikael
M
Hedblom
Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden.
My
M
Mattsdotter Björk
Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden Institute of Marine Research, Tromsø, Norway.
Melissa
M
Chierici
Department of Biological and Environmental Sciences, University of Gothenburg, Göteborg, Sweden.
Angela
A
Wulff
D000064:Acclimatization; D000864:Antarctic Regions; D002245:Carbon Dioxide; D002254:Carbonates; D017377:Diatoms / Q000254:growth & development* / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D012623:Seawater / Q000737:chemistry
D002254:Carbonates; D002245:Carbon Dioxide
Southern Ocean; algae; bacterial production; climate change; polar; primary production