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Higher sensitivity towards light stress and ocean acidification in an Arctic sea‐ice‐associated diatom compared to a pelagic diatom
Author(s) -
Kvernvik Ane C.,
Rokitta Sebastian D.,
Leu Eva,
Harms Lars,
Gabrielsen Tove M.,
Rost Björn,
Hoppe Clara J. M.
Publication year - 2020
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.16501
Subject(s) - pelagic zone , acclimatization , diatom , biology , arctic , ecology
SummaryThalassiosira hyalina and Nitzschia frigida are important members of Arctic pelagic and sympagic (sea‐ice‐associated) diatom communities. We investigated the effects of light stress (shift from 20 to 380 µmol photons m −2 s −1 , resembling upwelling or ice break‐up) under contemporary and future p CO 2 (400 vs 1000 µatm). The responses in growth, elemental composition, pigmentation and photophysiology were followed over 120 h and are discussed together with underlying gene expression patterns. Stress response and subsequent re‐acclimation were efficiently facilitated by T. hyalina , which showed only moderate changes in photophysiology and elemental composition, and thrived under high light after 120 h. In N. frigida , photochemical damage and oxidative stress appeared to outweigh cellular defenses, causing dysfunctional photophysiology and reduced growth. p CO 2 alone did not specifically influence gene expression, but amplified the transcriptomic reactions to light stress, indicating that p CO 2 affects metabolic equilibria rather than sensitive genes. Large differences in acclimation capacities towards high light and high p CO 2 between T. hyalina and N. frigida indicate species‐specific mechanisms in coping with the two stressors, which may reflect their respective ecological niches. This could potentially alter the balance between sympagic and pelagic primary production in a future Arctic.