Antarctic microalgae: physiological acclimation to environmental change

• Main Author: Rajanahally, Meghana Amarnath
• Other Authors: Lester, Phil, Convey, Peter
• Format: Master Thesis
• Language: English
• Published: Victoria University of Wellington 2014
• Subjects: Antarctica; Algae; Sea ice; Antarctic; Southern Ocean; Antarc*; ice algae
• Online Access: http://researcharchive.vuw.ac.nz/handle/10063/3643

Sea ice algal communities play a very significant role in primary production in the Southern Ocean, being the only source of fixed carbon for all other life in this habitat and contributing up to 22% of Antarctic primary production in ice-covered regions. Therefore it is important to understand how these organisms adapt to this highly variable and harsh environment Previous studies have described their acclimation to changes in environmental conditions but we still do not understand the physiological basis of these responses. This study examines the effects of varying levels of photosynthetically active radiation (PAR), ultraviolet-B (UV-B) radiation and temperature on bottom ice algal communities and individual algal species using pulse-amplitude modulation (PAM) fluorometry, the production of mycosporine-like amino acids (MAAs) and superoxide dismutase (SOD) activity. The experiments conducted in this thesis show that bottom ice algae are capable of acclimating to the higher levels of PAR and temperature that would likely be experienced during sea ice melt As temperature was increased past a threshold temperature of thylakoid integrity, it became the major stressor, causing decreases in photosynthetic yield at around 14°C, even at ambient PAR exposure. Similarly, a thylakoid integrity experiment independently suggested that the critical temperature for the onset of thylakoid damage was 14°C, which correlated well to the 14°C incubation observations, although this is a temperature that sea ice algae are unlikely to encounter in the polar regions. It is likely that sea ice algae produce additional MAAs, known to be cellular sunscreens, in response to increasing levels of UV-B, allowing tolerance of this stressor. This is the first study in the marine environment to demonstrate that algae can produce MAAs in response to increasing PAR and temperature, even in the absence of UV-B, indicating that MAAs may be more than just sunscreen compounds. The levels of UV-B used in this study were representative of those ...