Articles | Volume 10, issue 2
Biogeosciences, 10, 1143–1153, 2013

Special issue: Arctic ocean acidification: pelagic ecosystem and biogeochemical...

Biogeosciences, 10, 1143–1153, 2013

Research article 20 Feb 2013

Research article | 20 Feb 2013

Effect of ocean acidification on the fatty acid composition of a natural plankton community

E. Leu1,*, M. Daase1, K. G. Schulz2, A. Stuhr2, and U. Riebesell2 E. Leu et al.
  • 1Norwegian Polar Institute, FRAM Centre, 9296 Tromsø, Norway
  • 2Helmholtz Centre for Ocean Research Kiel (GEOMAR), 24105 Kiel, Germany
  • *now at: Alfred-Wegener-Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany

Abstract. The effect of ocean acidification on the fatty acid composition of a natural plankton community in the Arctic was studied in a large-scale mesocosm experiment, carried out in Kongsfjorden (Svalbard, Norway) at 79° N. Nine mesocosms of ~50 m3 each were exposed to 8 different pCO2 levels (from natural background conditions to ~1420 μatm), yielding pH values (on the total scale) from ~8.3 to 7.5. Inorganic nutrients were added on day 13. The phytoplankton development during this 30-day experiment passed three distinct phases: (1) prior to the addition of inorganic nutrients, (2) first bloom after nutrient addition, and (3) second bloom after nutrient addition. The fatty acid composition of the natural plankton community was analysed and showed, in general, high percentages of polyunsaturated fatty acids (PUFAs): 44–60% of total fatty acids. Positive correlations with pCO2 were found for most PUFAs during phases 2 and/or 3, with the exception of 20:5n3 (eicosapentaenoic acid, EPA), an important diatom marker. These correlations are probably linked to changes in taxonomic composition in response to pCO2. While diatoms (together with prasinophytes and haptophytes) increased during phase 3 mainly in the low and intermediate pCO2 treatments, dinoflagellates were favoured by high CO2 concentrations during the same time period. This is reflected in the development of group-specific fatty acid trophic markers. No indications were found for a generally detrimental effect of ocean acidification on the planktonic food quality in terms of essential fatty acids.

Final-revised paper