Size scaling of photophysiology and growth in four freshly isolated diatom species from Ryder Bay, western Antarctic peninsula

• Published in: Journal of Phycology
• Main Authors: Kulk, Gemma, Buist, Anton, van de Poll, Willem H, Rozema, Patrick D, Buma, Anita G J
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2019
• Subjects: Carbon uptake; diatoms; electron transport; photophysiology; size scaling; west Antarctic peninsula; SOUTHERN-OCEAN PHYTOPLANKTON; FRAGILARIOPSIS-CYLINDRUS BACILLARIOPHYCEAE; NORTHERN MARGUERITE BAY; PHAEOCYSTIS-ANTARCTICA; CHLOROPHYLL FLUORESCENCE; INTERANNUAL VARIABILITY; DIADINOXANTHIN CYCLE; EXCESSIVE IRRADIANCE; TAXA PHOTOSYNTHESIS; ELECTRON-TRANSPORT; Antarctic; Antarctic Peninsula; Marguerite; Marguerite Bay; Ryder; Ryder Bay; Southern Ocean; Antarc*; Antarctica
• Online Access: https://hdl.handle.net/11370/59eba522-a940-4e5b-baf2-847e88be0f5c; https://research.rug.nl/en/publications/59eba522-a940-4e5b-baf2-847e88be0f5c; https://doi.org/10.1111/jpy.12813; https://pure.rug.nl/ws/files/80571703/Kulk_et_al_2019_Journal_of_Phycology.pdf

Diatoms are one of the dominant groups in phytoplankton communities of the western Antarctic Peninsula (WAP). Although generally well-studied, little is known about size dependent photophysiological responses in diatom bloom formation and succession. To increase this understanding, four Antarctic diatom species covering two orders of magnitude in cell size were isolated in northern Marguerite Bay (WAP). Fragilariopsis sp., Pseudo-nitzschia cf. subcurvata, Thalassiosira cf. antarctica, and Proboscia cf. alata were acclimated to three different irradiances after which photophysiology, electron transport, carbon fixation and growth were assessed. The small species Fragilariopsis sp., Pseudo-nitzschia cf. subcurvata, and large species Proboscia cf. alata showed similar photoacclimation to higher irradiances with a decrease in cellular chlorophyll a and an increase in chlorophyll a specific absorption and xanthophyll cycle pigments and activity. In contrast, pigment concentrations and absorption remained unaffected by higher irradiances in the large species Thalassiosira cf. antarctica. Overall, the small species showed significantly higher growth rates compared to the large species, which was related to relatively high light harvesting capacity and electron transport rates in the smaller species. However, photophysiological responses related to photoinhibition and photoprotection and carbon fixation showed no relationship to cell size. The present study supports the dominance of small diatoms at low irradiances during winter and early spring, but does not provide photophysiological evidence for the dominance of large diatoms during the phytoplankton bloom in the WAP. This suggests that other factors such as grazing and nutrient availability are likely to play a major role in diatom bloom formation. This article is protected by copyright. All rights reserved.