Photosynthetic studies on Antarctic autotrophs from James Ross Island: Field and aboratory experience
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| Year of publication | 2014 |
| Type | Conference abstract |
| MU Faculty or unit | |
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| Description | To study long-term effects of atmospheric warming, open top chambers (OTCs) were installed over typical vegetation covers at the James Ross Island in 2007/2008. Altogether, 9 OTCs with microclimate and vegetation cover monitoring are recently in operation: 3 OTCs at coastal area, 3 at a plateau of a deglaciated mesa, and 3 at a glacier forefield at a mesa. In this presentation, only moss-dominated coastal location is focused because it shows the highest species richness. At this experimental plot, the below-specified long-term photosynthetic measurements are carried out. To estimate photosynthetic processes and physiologically active time of Bryum sp. inside OTCs and at outside control plots, several fluorometers (Photon Systems Instruments, CZ) were used. Since February 2010, when they were installed in close vicinity of the J.G.Mendel station (northern part of the James Ross Island), they have been permanently in operation. In 1h step, they measure chlorophyll fluorescence and effective quantum yield of photosynthetic processes in photosystem II (YieldPS II) as dependent on hydration/dehydration and microclimatic parameters. For the calculations, the equation YieldPS II = (F´m - Fs)/F´m is used, where Fs is steady state chlorophyll fluorescence (Fs) on light and F´m is maximum chlorophyll fluorescence in light adapted state (F´m). In this way, yearly data on photochemical processes of photosynthesis are available showing inhibition of photosynthesis due to e.g. freezing, and unavailability of light during winter season. In laboratory, several experiment have been done focusing e.g. resistance to PAR- and/or UV-induced photoinhibition of photosynthesis in Usnea antarctica, Umbilicaria decussata and Xanthoria elegans. Species-specific differences in photoprotective mechanisms have been studied. Resistances to partial dehydration of lichen thalli, low and freezing temperatures have been addressed as well. |
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