Whilst I was enjoying myself in Venice and the Dolomites, most of my family were hard at work earning an honest crust or studying. One, however, was looking at mountains considerably higher than anything that Europe has to offer. As she was, technically, reconnoitring locations for a study visit to Kashmir and Ladakh next summer she will tell us that it was work rather than holiday, but we should treat this claim with a generous pinch of salt.
Pangong Tsu, looking east towards the distant mountains of Tibet. September 2014 (photo: H. Kelly)
One souvenir of her visit was a small sample of algae from the littoral zone of the remote Pangong Tsu at an altitude of 4266 metres on the Indian-Tibetan border. Problem #1 for anyone working in such locations is how to preserve samples for the journey home. There is a simple solution: buy a bottle of cheap local vodka. My limited experience of Indian spirits is that using them to preserve algae is a better option than drinking them and, in any case, the high altitude of Ladakh will give the partially-acclimated traveller a cracking headache without any need for chemical assistance. The downside is that the cell contents are not preserved very well but as diatomists are mostly interested in the silica cell wall this is not a problem.
A view of the periphyton from the littoral zone of Pangong Tsu (approx.. 33° 45’ N, 78° 38’ E), photographed at 400x magnification.
A first look at the sample down my microscope revealed a number of diatoms that looked broadly familiar though which differ in detail from species with which I am familiar with in Europe. There were, for example, a lot of cells of Gomphonema, each at the end of a long stalk, though these were not a species that I recognised. Within this tangle of stalks, I could see a number of zig-zag chains of a species of Diatoma but, again, it was not a form I had seen in Europe. There were other taxa, too, but I will wait until I have cleaned the material and prepared a permanent slide before commenting further.
Gomphonema cells from the littoral zone of Pangong Tsu, September 2014. The four cells on the left are in valve view; the two on the right are in girdle view. The stalk is visible on the right hand image. Scale bar: 10 micrometres (= 1/100th of a millimetre).
Cells of Diatoma from the littoral zone of Pangong Tsu, September 2014. The lefthand image is in valve view; the central and right hand images are in girdle view. The central image shows a cell that has recently divided. The cells are joined at the corners to form zig-zag colonies. Scale bar: 10 micrometres (= 1/100th of a millimetre).
There seems to be very little published on Pangong Tsu, as befits its remote location. One early visitor was the famous limnologist G. Evelyn Hutchinson, as part of the Yale North India Expedition in the early 1930s. The papers that I did find told me that the water of Pangong Tsu is slightly brackish, as the lake has no outlets and water is lost by evaporation. However, I usually associate Gomphonema with freshwater habitats, suggesting that the brackish influence is very weak. There is also evidence of very high concentrations of phosphorus in the lake, although nitrogen concentrations are very low. This suggests that growth of the organisms in the lake may be limited by nitrogen rather than phosphorus, as is usually the case in lakes. I would be interested to know why a lake that is so remote contains phosphorus concentrations that are usually associated with human activity.
The next step is to make some permanent slides from the material and have another look, then see if any of the diatoms in this sample correspond to species found elsewhere in the region or beyond. There is a chance, based on the lake’s isolation and recent discoveries that the diversity of diatoms was much greater than hitherto thought, that there may be some previously undescribed species living in this unusual habitat.
Bhat, F.A., Yousuf, A.R., Aftab, A., Arshid, J., Mahdi, M.D. & Balkhi, M.H. (2011). Ecology and biodiversity in Pangong Tsu (lake) and its inlet stream in Ladakh, India. International Journal of Biodiversity and Conservation 3: 501-511.
Hutchinson, G.E. (1933). Limnological studies at high altitudes in Ladakh. Nature (London) ##: 132-136.
Hutchinson, G.E. (1937). Limnological studies in Indian Tibet. Int. Hydrobiol. 35: 134-177.