Resilience to UV radiation and high PAR in the marine Chlorophyte Dunaliella tertiolecta and the interaction of increased CO2 in the context of global change

Résumé

UVR is considered a prime factor able to cause detrimental effects on phytoplankton (Vincent & Roy 1993). It is particularly relevant when considering the increase in ultraviolet-B radiation reaching the ocean surface due to the depletion of stratospheric ozone layer, and aggravated by other global change conditions (McKenzie et al. 2011; Zepp et al. 2007). This work has demonstrated that D. tertiolecta is highly resilient to both UVR and high PAR during long-term exposure: it responds to stress, and it can unexpectedly survive for at least 6 days. To explain how a photoautotrophic unicellular alga is able to cope with the damaging effects of the two abiotic stressors used, D. tertiolecta was exposed to different treatments and periods of PAB. It always showed a remarkable ability to survive, and even to recover some functions once the stress finished. Moreover, the interference of rising CO2, as a main driver of global change, has been assessed in the PAB survival and stress tolerance. Despite that high PAR and UVR in any of the experiments did not produce significant cell mortality, the physiological response and the repair mechanisms triggered were not always the same. References: Mckenzie RL, Aucamp PJ, Bais AF, et al. 2011. Ozone depletion and climate change: impacts on UV radiation. Photochemical and Photobiological Sciences 10, 182–198. Vincent WF, Roy S. 1993. Solar ultraviolet-B radiation and aquatic primary production: damage, protection, and recovery. Environmental Reviews 1, 1–12. Zepp RG, Erickson DJ, Paul ND, Sulzberger B. 2007. Interactive effects of solar UV radiation and climate change on biogeochemical cycling. Photochemical & photobiological sciences: Official journal of the European Photochemistry Association and the European Society for Photobiology 6, 286–300.