Taxon-specific survival strategies to prolonged darkness and re-exposure to light in diatoms and flagellates: impact on phytoplankton community structure in the Southern Ocean

Pezzola, Caterina (2021) Taxon-specific survival strategies to prolonged darkness and re-exposure to light in diatoms and flagellates: impact on phytoplankton community structure in the Southern Ocean. Master's Research Project 1, Marine Biology.

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Abstract

Phytoplankton populations in the Southern Ocean have to withstand prolonged periods of darkness (i.e. polar night, sea-ice cover), followed by extended periods of daylight. The development of adaptations to seasonal changes in irradiance were investigated through laboratory experiments. In our study, three Antarctic diatoms (Thalassiosira antarctica, Fragilaropsis minimum, Chaetoceros brevis) and three flagellates (Pyramimonas sp. (Prasinophyceae), Phaeocystis antarctica (Haptophyceae), Polarella glacialis (Dinophyceae)) were light deprived for 8 weeks. To test the ability to recover upon return of irradiance, a sub- sample was weekly re-exposed to dim light for 5 consecutive days. Chl-a concentration and photosynthetic characteristics of photosystem II were examined both during the dark treatment and after recovery in irradiance. Both diatoms and flagellates showed a loss of photosynthetic efficiency during darkness. After 5 days of re-exposure to light, diatoms showed better recovery compared to flagellates. The effects of 8 weeks of darkness on Chl-a synthesis and PSII functionality were reversible in all three diatom species. Flagellates on the other hand could hardly overcome the photodamage and displayed poor shape by the end of the experiment. The ability to stay viable and overcome damage may grant diatoms competitive advantage over flagellates and allow the exploitation of nutrient stocks upon return of irradiance, and eventually shape spatial distribution.

Item Type:	Thesis (Master's Research Project 1)
Supervisor name:	Poll, W.H. van de
Degree programme:	Marine Biology
Thesis type:	Master's Research Project 1
Language:	English
Date Deposited:	31 May 2021 14:46
Last Modified:	31 May 2021 14:46
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/24476

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