lundi 17 janvier 2011

The fluorometry experiments on the ridge

I have finished the first part of the fluorescence measurements on the ridge. As you can see on the picture below, I have put plastic squares on the biofilms to mark the place where the fluorometer is located, and I have positioned the temperature sensors just nearby. The fluorometer and the PAR-meter (thanks Elie!) are working well.The PAR-meter is measuring the light of 400-700 nm wavelenght, which can be used by the photosynthetic organisms. The fluorometer measures the photosynthetic efficiency.
The best signal (high Fv/Fm amplitude during day)  was on the site 1 (you cannot see it on the photo above because it is under the ice).  I have noticed that the temperature and humidity were also the highest at site 1. I get the impression that the cover of ice does not hinder the photosynthetic activity. In fact, when we tried to estimate the snow transparency with the PAR-meter, we found that under 40 cm of snow, there was still enough light.

On the Utsteinen ridge, drifting and blowing snow are the most important sources of water, as you can see on this picture. When there is enough sunlight, the snow is melting and liquid water is present. This melting happens during a relatively short period, and depends on the angle of the slope and other factors (shadows of rocks,…).  The sun angle is quite small (up to ~35 degrees) in this part of Antarctica, even during summer. The reflection from the surface of the ice/snow is quite high at such an angle. Therefore, you really need to have a perfect slope orientation to have good conditions for life. Thus, small differences in the relief and topography can make a huge difference in the ‘habitability’ of the sites.
Cheers, Zorigto

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