Oct. 9th, 2002

Edmond "Ed" Grin

D -7 before departure!

Exploring Life Underwater and the Waves of Light

Today we will have a first look at experiment procedures related to one of the UV radiation experiments of the expedition. As you've seen, the sub-title of the expedition is “Exploring the Life at the Extreme”. Why? The search for the origin of life is helping us to discover and understand the adaptation strategies of living organisms. These strategies allowed them to survive in extreme environments since the early Archean period (about 3.5 Ga ago) when life may have begun on Earth in and/or near water.

The Licancabur local is a unique site to study the evolution of living organisms subjected to extreme condition. We understand from previous archeological expeditions to the volcano that the summit lake in the caldera at 19500 ft (5916 m) is a swampy (residual?) pond that host insects and living organisms, and possibly also algae. The high altitude, and the clearest sky of the world of the Atacama desert, combines to form a unique site to investigate the effects of UV.
During the reconnaissance expedition last July we observed flamingos eating algae in the high altitude lakes (lagunas) at 13000 ft --about 4145 meters [see Fig. 1] at the foot of Licancabur. That really puzzled us to see these birds so high. The environment of the lagunas is also something we would like to understand. Because they are lower than the Licancabur Lake, they will provide us intermediate points of information on how the solar radiation, specifically the UV radiation, affects the living organisms at various altitudes. We will be then able to compare the results with the summit lake.

Some parts of the solar radiation have detrimental effects on the organisms. Life has to develop strategies to survive. It must select habitats that will allow their biological machinery, particularly the genetic component (DNA) and the photosystem to adapt. The effects of the solar radiation can be well investigated in the photosystem of algae.

Now, just a few words about the solar light that will help us understand how we will study the effects of the solar radiation on algae. The solar light spectrum --illustrated by the rainbow or light passing through a glass prism-- includes light that is visible to our retina as well as ultraviolet (UV) and infrared light that are both undetectable by the human eye. If you want to learn more about light wavelength, you can check the following URL: http://spaceguard.ias.rm.cnr.it/ tumblingstone/issues/num8/light/Spectrum.htm

The UV spectrum is commonly divided in three ranges (see Fig. 2): The UV-A is responsible for tanning the human skin. The UV-B causes the most photochemical degradation as well as sunburns. It also degrades materials such as plastic. This is why --as you will see in the next paragraphs-- we cannot use this type of material for our experiments. Instead, we will use a special non-degradable plexiglas. UV-C radiation is absorbed in the ozone layer. The most damaging light wavelengths are the UV-C and UV-B short- regions of the spectrum.

Our research on the effects of the UV radiation at both the Licancabur and the lagunas will be divided into the field experiments which will allow us to observe the organisms living in these lakes in their natural sub-lacustrine (under water) habitat and the laboratory analysis of samples that we will bring back from the field.

The procedure of the field work is mainly to install grazer enclosures in shallow water in the lakes where we believe algae are living. We will test the effects of the UV radiation by harvesting the biomass (living organisms) from the underside of submerged 60 X 60 cm plexiglas sheets suspended on plexiglas rods 10 cm above the bottom lake sediment.
Each station will be composed of one UV filtering plexiglas sheet that absorbs the incident UV light. The same material is actually used to protect valuable museum artifacts and photos from damaging effects of UV rays. The filtering sheet is coupled with a UV transmitting sheet specially formulated to resist the degradation caused by continuous exposure to UV. A mesh of nylon will be mounted around the sheet to form a closed gazer chamber that will protect the algae from unwanted "intruders" that could disturbed the experiment (mostly small fishes --if any-- or any other bigger animals).

We will do a preliminary harvest before we leave, after about 2 weeks of exposure but we will also leave this experiment much longer. In fact, we will come back in 2003 and after one year we will harvest the underside of the sheets and collect the algae off the gazer chamber for further analysis in laboratory. We will compare the two harvests to discover what are the notable differences between the algae that were protected by the filtering plexiglas and those which were not. There will be 4 stations in each laguna and one or two in the summit lake installed in shallow water.

Cool Ideas of Experiments about Solar Radiation…

You can study the effects of the solar radiation on a leaf of salad or spinach that you can enclosed between two nickels. Leave the leaf with its stem in the water in a plate during a week or more. After this period of time, remove the nickels. You will see the effect of the depletion of light below the nickel. Compare this experiment with a leaf protected by a good UV filtering sun glass.