Ocean acidification and high irradiance stimulate the photo-physiological fitness, growth and carbon production of the Antarctic cryptophyte Geminigera cryophila

• Published in: Biogeosciences
• Main Authors: Trimborn, Scarlett, Thoms, Silke, Karitter, Pascal, Bischof, Kai
• Format: Text
• Language: English
• Published: 2019
• Subjects: Antarctic; The Antarctic; Antarc*; Ocean acidification
• Online Access: https://doi.org/10.5194/bg-16-2997-2019; https://www.biogeosciences.net/16/2997/2019/

Ecophysiological studies on Antarctic cryptophytes to assess whether climatic changes such as ocean acidification and enhanced stratification affect their growth in Antarctic coastal waters in the future are lacking so far. This is the first study that investigates the combined effects of the increasing availability of p CO 2 (400 and 1000 µ atm) and irradiance (20, 200 and 500 µ mol photons m −2 s −1 ) on growth, elemental composition and photophysiology of the Antarctic cryptophyte Geminigera cryophila . Under ambient p CO 2 , this species was characterized by a pronounced sensitivity to increasing irradiance with complete growth inhibition at the highest light intensity. Interestingly, when grown under high p CO 2 this negative light effect vanished, and it reached the highest rates of growth and particulate organic carbon production at the highest irradiance compared to the other tested experimental conditions. Our results for G. cryophila reveal beneficial effects of ocean acidification in conjunction with enhanced irradiance on growth and photosynthesis. Hence, cryptophytes such as G. cryophila may be potential winners of climate change, potentially thriving better in more stratified and acidic coastal waters and contributing in higher abundance to future phytoplankton assemblages of coastal Antarctic waters.