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

• Published in: Biogeosciences
• Main Authors: E. Leu, M. Daase, K. G. Schulz, A. Stuhr, U. Riebesell
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2013
• Subjects: Ecology; QH540-549.5; Life; QH501-531; Geology; QE1-996.5; Arctic; Svalbard; Norway; Kongsfjord*; Kongsfjorden; Ocean acidification; Phytoplankton
• Online Access: https://doi.org/10.5194/bg-10-1143-2013; https://doaj.org/article/0eab36a083424a2fa053ae45d65c45a3

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 m 3 each were exposed to 8 different p CO 2 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 p CO 2 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 p CO 2 . While diatoms (together with prasinophytes and haptophytes) increased during phase 3 mainly in the low and intermediate p CO 2 treatments, dinoflagellates were favoured by high CO 2 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.