Back to the Himalayas …

It is always nice to tie up loose ends left in earlier posts, so I was pleased to find a recent paper that put a name on a diatom that I had illustrated, but not been able to name, during my examination of material from a high altitude lake in Ladakh (see “Diatoms from Pangong Tso”).   I had assumed that this was a species of Gomphonema; however, Pat Kociolek and colleagues have placed it in a completely new genus, Gomphosinica.

Following their paper, the diatom that was abundant in the littoral of Pangong Tso is most likely Gomphosinica lacustris and this would be the first record of the genus in India.  The type location for this species is Kalakule Lake in the Kunlum Mountains of Xianjiang Province, northwest China, some 800 km north of Ladakh, and on the other side of the Tibetan Plateau.   They describe their sample as “planktonic in the lake”, whereas the populations I described formed distinct growths in the littoral zone (see “Return to Pangong Tso”).  They also have recorded it from Sichuan province, in southwest China.   Pangong Tso actually marks the Indian-Chinese border, so it should not be a great surprise to have found it here.

Altogether, Pat Kociolek and colleagues found three new species of Gomphosinica in China, and transferred a previously-described species of Gomphonema found in Nepal to the genus.  However, they also found four species in Montana, in the USA, and made one further transfer of a Gomphoneis first described from the Great Lakes.  Bear in mind, too, that Gomphosinica species are distinctive, so it is unlikely that the absence of Gomphosinica in regions other than China and the USA is an oversight on the part of diatomists.  There is clearly more to learn about the biogeography of this genus.

Having said that Gomphosinica is distinctive, it is hard to say exactly how it differs from Gomphonema based on what we can see with the light microscope alone.  The distinctive features can only be seen with scanning electron microscope, and it would be interesting to get some molecular barcodes from members of this genus to see how these compare with those from Gomphonema and relatives.  This might also shed some light on the differences between the North American and Asian species.

The same journal part also contained a paper on diatoms from the Doon Valley, near Dehra Dun in Uttarakhand, which may shed some light on the diatoms that I found nearby in the Ganges at Rishikesh (see “Diatoms from a holy river”).   I named these using the identification literature that I had to hand (mostly from Europe) and included “Gomphonema pumilum” in my list.  This new paper suggests that there may be local species which look very similar, including G. juettnerii and G. doonensis.   My population does not fit the dimensions of either of these exactly, and my inclination would still be that at least the larger of the two specimens I illustrated is G. pumilum, but there is enough in this paper to remind me that trusting a European flora when studying the diatoms of Asia is dangerous.   Whether these diatoms actually fill different niches in their respective ecosystems, or whether they are just genetically-distinct forms of what is, basically, food for relatively unfussy invertebrate larvae on both continents is a question for another day.

Note: the photograph at the top of the post is an early-evening view of a river in the Outer Himalaya Zone in the vicinity of Dehra Dun.

Reference

Karthick, B., Nautiyal, R., Kociolek, J.P. & Ramachandra, T.V. (2015).  Two new species of Gomphonema (Bacillariophyceae) from Doon Valley, Uttarakhand, India.  Nova Hedwigia, Beiheft 144: 166-174.

Kociolek, J.P., You, Q-M., Wang, Q-X. and Liu, Q. (2015).  A consideration of some interesting freshwater gomphonemoid diatoms from North America and China, and the description of Gomphosinica gen. nov..  Nova Hedwigia, Beiheft 144: 175-198.

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Diatoms from the Valley of Flowers

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My visit to the Valley of Flowers in India (see “Into the Valley of Flowers …”) is a fast fading memory but I have finally managed to get the diatom samples that I smuggled into my suitcase properly mounted and spent some time last weekend peering down my microscope and trying to match what I could see with the habitat that I remembered.

The sample I collected came from a first order stream which appeared from the mouth of a glacier a couple of hundred metres above us on the [north] side of the valley.  About 500 metres downstream it joined the Pushpanati River, a tributary of the Aleknanda, itself a tributary of the mighty Ganges.   It was just over a metre wide and a few centimetres deep and had a mixture of pebbles and gravel as its substratum.  Some of the larger stones were encrusted with what looked like growths of Chamaesiphon  (see “A bigger splash …“).  There were also a few flocs of green algae which turned out to be Zygnema, a relative of Mougeotia and Spirogyra ( see “Fifty shades of green …”) with two distinctive star-shaped chloroplasts.  They are not at their best in the photograph below because they made the journey from India to the UK soused in local vodka (a cheap and effective preservative for algae: your liver will not begrudge you this particular experience …).

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Vinood, our guide, looking at the stream that I sampled in the Valley of Flowers, August 2016.

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Vodka-soused Zygnema sp from a glacier-fed tributary stream of the Pushpanati River (Valley of Flowers),  August 2016.  Scale bar: 20 micrometres (= 1/50th of a millimetre).

The diatoms were a surprise as almost all belonged to a single species, Diatoma mesodon, a species familiar to me from very high quality streams in Europe.  Ninety-five percent of all the diatoms I looked at belonged to this species, an unusually high proportion compared with other samples that I have examined, especially as there are no human pressures in the area that might influence diversity.   The Diatoma cells formed zig-zag chains, though these fell apart during the preparation process and the images just show individual valves.   Other diatoms present in small numbers included Meridion circulare var. constrictum (syn: Meridion constrictum) and two species of Eunotia, all of which suggest relatively soft water.

The low diversity intrigued me.   I have seen very low diversity with headwater streams, possibly because there is low potential for organisms from upstream to “seed” the location.   As small tributaries merge, so incocula from the sparse assemblages of these headwater streams will combine to create more diverse communities downstream.  Curiously, a recent paper argues the opposite: that headwaters are, in fact, hotspots of microbial diversity, and that this declines with increasing distance downstream.   However, this study takes a much broader view than just algae.  The authors suggest that it the close connection between headwater streams and the surrounding catchment leads to soil bacteria being washed into the stream.   So this result does not really contradict my observation; rather it highlights the limited insight that one may glean through looking at a single group of organisms.

Had I had more time (and more samples containers), it would have been interesting to follow the valley as far upstream as possible, to see if the other streams flowing down from the hillside had similar assemblages of algae, or if their algae were different.   My guess is that the patchwork of habitats would mean that the total diversity for the valley (“beta diversity”) would be considerably greater than the diversity at any particular site (“alpha diversity”).   If anyone wants to test this hypothesis, then all they need to do is make a three day journey from Delhi, with an extra day set aside for acclimatisation, followed by a two day hike up to a height of 3500 m.  And don’t forget to pack that bottle of vodka …

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Diatoma mesodon from a glacier-fed tributary stream of the Pushpanati River (Valley of Flowers), August 2016.   a. – e.: valve views; f. – g.: girdle views.  Scale bar: 10 micrometres (= 1/100th of a millimetre.

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Other diatoms from a glacier-fed tributary stream of the Pushpanati River (Valley of Flowers),  August 2016,  a. – b.: valve and girdle views of Meridion circulare var. constrictum; c. Eunotia islandica; d. E. paratridentula; e. Cymbella cf naviculiformis.  Scale bar: 10 micrometres (= 1/100th of a millimetre).

Reference

Besemer, K., Singer, G., Quince, C., Bertuzzo, E., Sloan, W. & Battin, T.J. (2016).  Headwaters are critical reservoirs of microbial diversity for fluvial networks.  Proceedings of the Royal Society of London Series B 280: DOI: 10.1098/rspb.2013.1760

Into the Valley of Flowers …

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I can safely say that our hotel in Ghangharia was one of the worst in which I have ever stayed.  The rooms were draughty, dirty and damp, there was no hot water and the cheerful Nepali kitchen staff had a very limited grasp of health and safety.  This is one of the downsides of being a Guinea pig for a tour party: we stayed in two excellent hotels and three perfectly adequate ones but, occasionally, we have to suffer so that next year’s paying guests don’t have to.   The tented camp, just outside the village, looks like a much better bet for next year.

On the plus side, the low cloud disappeared overnight and we awoke to blue skies with just a few puffy cumulus clouds and gulped lungfuls of cool mountain air in order to banish the fetid atmosphere of the hotel.   The track out of Ghangharia was quiet: the Sikh pilgrims have to walk further and climb higher than those of us heading to the Valley of Flowers, so had made earlier starts.   We paid our 600 rupee entrance fees at a hut beside the path just after our route diverged from the path that the Sikhs took, and followed the track through a fir forest overhung by enormous vertical cliffs of much-folded ancient rocks.

The Valley of Flowers is a hanging valley – a glacial valley which ends in an abrupt drop as it joins with the valleys below.  This meant another stiff climb along a path that zig-zagged up a hillside and across the site of recent landslides.  We were now walking at about 3500 metres, and I was reminded of the limitations of my acclimatisation programme with every step.  But we had reached the tree line and the valley had broadened out to give us our first views of the valley that Smythe had first seen in 1931.   From where we stood at the western end, the valley extended for about five km due west before reaching the foot of the Tipra glacier. Behind these, peaks (several climbed for the first time by Smythe and his associates) rose to 6600 metres although, during our visit, most were hidden by clouds.  On either side of the valley there were lateral moraines deposited by the glacier in colder times whilst the Pushpawti river, carrying the glacier’s meltwater, has gouged out a V-shaped notch along the mid-line of the valley.

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Looking west up the Valley of Flowers towards Tipra glacier with stands of balsam in the foreground.  The photograph at the top of the post shows our first view of the Valley on arrival from Ghanghria.

There was a profusion of flowers but, to our mutual surprise, the most abundant by far, especially close to the mouth of the valley, was Himalayan balsam, scourge of British river banks (see “The politics of pests”).  After a while, however, we started seeing more diversity, especially in areas where the balsam was less prevalent and as we pushed further into the valley.  Everyone has to leave the valley by nightfall, which limits the distance that visitors can penetrate to a couple of kilometres, so there were many areas that Smythe described but which we could not visit.  Nonetheless, Heather, the real botanist in the family, photographed about 100 different species (her own accounts will follow) at a time of year when important groups such as Primula and the orchids are long past their best.

The prevalence of balsam was intriguing.  This is its native habitat, and we don’t have enough knowledge of the plant communities in this part of the world to know how typical these extensive stands of balsam are at these altitudes.  Smythe reported its presence but also commented that it was ruining pastures in the area.  However, he only made a couple of visits so his opinion, too, may not be definitive.  We did learn from a park ranger that the cover of balsam had increased in recent years.  When the valley was declared as a World Heritage Site grazing was banned and though this was at a very low level (a single family), we did wonder whether this had a role in maintaining habitat.   On the other hand, the balsam here is much more varied than the monocultures of Impatiens glandulifera that we are used to seeing in the UK, where it was introduced and perhaps we are approaching it with minds pre-conditioned by negative attitudes at home?   I. glandulifera is found in the valley, but I. sulcata, the Giant Himalayan balsam, is more common here.   There is no doubt that the splashes of pink-purple flowers across the floor of the valley were a dramatic fulfilment of many peoples’ expectations as they first entered the valley.

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Valley of Flowers, looking west at about 1.5 km from the foot of Tilpri glacier.   The plants in the foreground are (probably) Campanula latifolia (bellflower) and Selinum wallichianum (milk parsley), one of several umbellifers that are found in the valley.

By now, the sun was sinking and we needed to start retracing our steps back down to Ghanghria.   Our personal odyssey was over; we had seen the Valley of Flowers. For Heather, at least, it is probably “au revoir” rather than “goodbye” as there is a strong chance that she will bring a tour party back here next year or the year after.   For me, who knows?

And, yes, I did collect some diatoms from a stream whilst I was in the Valley of Flowers.  I’ll write more about those at some point.  Somehow, too, I must have communicated my interest in the diversity of the microbial world to the kitchen staff of our hotel, as they kindly sent me back down the track to civilisation with a payload of grumbly enteric bacteria.  But you don’t want me to write too much about that …

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The Valley of Flowers, showing abundant stands of Persicaria polystachya, a very common plant along river banks (i.e. in the habitat where we would expect to find Himalayan balsam, Impatiens glandulifera, in the UK).

Hill tales from the ‘plane …

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From Rishiketh, we followed the Hindu and Sikh pilgrims as they made their way up the Ganges to the many sacred sites amidst the headwaters.   The road followed a narrow, twisting route high above the river, and Mohan, our driver, was often slowing to a crawl as we passed places where the debris from recent landslides littered the road.  Each turn opened up new views of tree-clad hills, with hamlets clinging to steep slopes and narrow terraces following the contours for rice cultivation.  We passed orange-clad sadhus (Hindu holy men) who were walking the whole distance to Badrinath (some 300 km from Rishiketh) and were, in turn, overtaken by less patient pilgrims in cars sporting orange flags and honking horns.  Macaque and, occasionally, langur monkeys, stared curiously at this procession through their valley whilst cows wandered to and fro across the highway in search of grazing.

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Rice fields clinging to a hillside near Joshinath in the upper Alaknanda Valley, Uttrakhand Province, August 2016.  The upper picture shows sunset over the Alaknanda just below Srinagar.

This is a pilgrimage, of sorts, for Heather and myself too.  Thirty years ago, I gave her a copy of Frank Smythe’s Valley of Flowers as an engagement present and our destination on this long, slow journey into the high Himalayas is the valley that Smythe first described back in 1937, and which is now a World Heritage Site, famed amongst botanists for its rich alpine flora (over 500 species of flowering plants).  Our slow progress up the valley was partly dictated by the terrain, but also by my need to acclimatise to the high altitude. Smythe first stumbled into the valley by chance whilst on a climbing expedition and, when the clouds shift, we get glimpses of high peaks in the far distance.

At Deoprayag, 68 km from Rishiketh, the Bhagirathi and Alaknanda rivers join to form the Ganges.  There is a  mass of brightly-coloured houses, each almost on top of the one below and, at the bottom, ghats, emphasising the importance of the confluence to Hindus.  Our route is along the Alaknanda, so we drop down to the bridge across the Bhagirathi, passed chai stalls and wayside eateries, and followed the road towards Badrinath, another important Hindu shrine, and Govind Ghat, the start point for the Sikh pilgrims’ trek as well as for the Valley of Flowers.  A little further on, we stopped at a busy little café with a row of pots bubbling away at the front for our lunch and ate vegetable thali with hot roti straight from the stove.

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Deoprayag, Uttrakhand Province, August 2016, where the light brown Bhagirathi (on the left of the picture) and the darker brown Alaknanda (on the right) join to form the River Ganges.

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Lunch stop at Biyasi, between Rishiketh and Srinagar, Uttrakhand Province, August 2016.

The complicated interplay between the sacred and secular continued as we moved up the Aleknanda valley.  The enormous power of the Ganges and her tributaries, fed by the monsoon rains and glacial meltwater, is a resource that a country with few other energy sources, a population of over a billion and huge ambitions cannot be wasted.  The first of several hydropower projects that we saw was at Srinagar, about 80 km above the confluence.   When the dam was closed in 2013, a temple to the goddess Hari Devi had to be relocated.  Within weeks, the devastating floods occurred in the valley, with over 15,000 fatalities.  Now, the government is paying for the temple to be rebuilt in exactly the same location, on a platform resembling a small oil rig accessed via a bell-lined gantry.

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The Hari Devi temple just upstream of Srinagar, Uttrakhand Province, August 2016.

We needed two overnight stops to cover the distance from Rishiketh to Govind Ghat, where we left the road set off on foot with cheerful groups of Sikh pilgrims along a footpath that wound along a forested valley of a tributary of the Alaknanda deeper into  the hills.   The vegetation changed as we climbed: pines, hazel and chestnut were amongst the trees that we recognised from home during the early stages of our trek.  These had replaced a mass of less-familiar trees – “jungle”, in the truest sense – on the lower slopes.  As the valley narrowed and the path grew steeper, the broadleaf trees became less common and first deodar cedars, later spruce and fir, appeared amongst the pines.

The early morning drizzle petered out as we climbed; rain ponchos were stowed and we walked on in tee-shirts and shorts, stepping aside periodically as columns of pack ponies pushed past us laden with supplies for the villages above us.  We paused at a chai stall, catching our breath as we looked back down the valley and at the churning river far below.  Then, we turned our eyes back to the path and continued upwards, pausing again to talk with a group of Sikh women from Leicester who were making the pilgrimage. By this stage I welcomed every opportunity to stop to catch my breath; I suspect that an extra day of acclimatisation would probably have been beneficial.

Lunch was fresh potato paratha, eaten with hot lime pickle and more chai, in a shack on a hillside, exchanging pleasantries with the stately patriarch of the Leicester clan before pushing on for the last kilometre or so, through a stand of fir trees and into the scruffy village of Ghangharia.  This is where the pilgrims – whether of Govind Singh or Smythe – spend their last night before the culmination of their journey.

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“Pharmoethnobotany” near Bhyundar, Uttrakhand Province, during our trek to the Valley of Flowers, August 2016.

Reflections from the River Ganges

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From Shimla we made our way across the Himalayan foothills to Deera Dun and, from there, to the Hindu holy town of Rishiketh, where our hotel room which overlooked the River Ganges, swollen and turbid following the monsoon rains. Rishiketh is, along with Varanasi, Allalahabad and Hardiwar, a place where Hindus believe that the veil between the earthly and celestial realms is at its thinnest, making prayers and puja performed here particularly auspicious. This may seem, at first sight, to be a long way from the science that I usually write about in this blog but a lot of my posts relate to how humans use rivers, and this includes spirituality (see also “Dipping a toe in the River Jordan

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Hindus performing puja in the River Ganges at Rishiketh. The upper picture shows sunrise over the Ganges, August 2016.

Travelling along the upper stretches of the Ganges emphasises that such uses should not be dismissed lightly: the river and its tributaries run through steep-sided unglaciated valleys, with little flat land for agriculture or development. The flux of Hindu pilgrims upstream from Rishiketh to shrines at Kedarnath and Badrinath provides a major source of income for the local economy. I’m writing this post in a village called Ghangharia which has one of the highest Sikh Gurudwara in the world (3048 m) and we shared the 11 km journey from the closest road with a constant stream of friendly Sikh pilgrims. This village is largely dependent upon these pilgrims, who use this as a base to trek to a high altitude lake associated with Guru Govind Singh.

But it is not enough simply to consider the benefits of spiritually purely in economic terms. Hindus venerate the river as a god. I have a private theory that one of the origins of religion is trying to explain “low frequency, high impact” events and the Ganges has plenty of these. When the monsoons fail, the crop lands that the Ganges irrigates cannot feed the people. When the monsoons are especially intense, there is widespread flooding and loss of life. In 2013 there were severe floods in the Bhyunder Valley, in which Ghangharia is situated, with a huge loss of life locally. One small village that we saw was half buried by river sediments – including huge boulders – moved by the flood waters. The inhabitants will have seen many monsoons pass over without any harm falling on their village. Yet, in 2013, catastrophe struck. The natural inclination at times like these is to wonder “why here? why now? why me?”

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Part of the village of Pulna, in Uttarakhand Province, India, submerged by river sediments following catastrophic floods in 2013.

It is easy for a westerner, watching the outward manifestation of faith, to be condescending about the veneration of a river as a god. Should not science and reason, we wonder, not now replace these old superstitions? Up to a point, yes. However, the floods in the UK last winter are evidence of the limitations of our empirical approach, particularly when dealing with low probabilities but there is a deeper reason too. A consequence of the western scientific approach has been an inclination to dominate the natural world, to use our knowledge to overrule natural forces. Man dictates how a river should behave using cement and concrete: we have lost the awe and reverence for nature that arises from a sense of its enormous potential power.

A binary split in attitudes to nature is too simplistic. My experience is that ecologists generally do have a reverence for the natural world, and some understanding of the complex interactions that interfere with straightforward cause-effect relationships. But we often work within organisations and structures created by engineers and bureaucrats, who have more simplistic notions about how the natural world should be governed. And, whatever I write about Hindus revering the Ganges as a god, in principle, the river is horribly polluted and, in the upper portions, impounded for hydroelectricity. There is a disconnect between theory and practice, particularly ironic as the central Hindu notion of karma is all about linking actions to consequences in the future. Or, as one Hindu philosopher put it, “… the cause holds the effect … in its womb”. There is, it would seem, scope for a healthy symbiosis between modern ecological thinking and a belief system that reveres, rather than tries to dominate, nature.

‘Plane Tales From The Hills

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I usually write a post and then struggle to find a suitable title. This time, reading Rudyard Kipling on a flight to India, the title came first and all I need to do was find words to fit it. The honest truth is that an event-free flight is the best kind of flight, and BA257 was just that. My highlight on long-haul flights is usually catching up on films that I have missed; this time I whetted the appetite for travel with Werner Herzog’s Queen of the Desert, a biopic about Gertrude Bell. I should claim her as a local hero (the Bell family once owned the pit in my village) except that her contribution to dividing up the Middle East in the aftermath of the First World War unwittingly helped to precipitate the current mess. But, hey, who needs historical accuracy when you have Nicole Kidman looking ice-cool and elegant amidst the desert heat? (Tony Blair is a local lad, too, so there must be something about the north east that makes its children completely unsuited to  Middle Eastern geopolitics …)

That’s “Plane Tales” explained. Sort of. Now for “From The Hills”. I’m writing this from Clarke’s Hotel, a venerable relic of the Raj in the former hill station of Shimla. I first visited Shimla (or “Simla”, as it was known in Kipling’s day) over 30 years ago. This time, I am back, meeting up with Heather as she reconnoiters another route for Indus Experience. She’s been here for three weeks already and whilst I soak up the exotic ambience, she marvels at such modern contrivances as the hot bath and cold beer.

Half a day in the heat of Delhi’s strength-sapping heat is enough to make you realise why the colonial administration decamped to the foothills of the Himalayas during the hottest period of the year. We (myself and Helen, a fellow “plus one”) followed in their footsteps, catching a train from Delhi to Kalka, and then transferring to a narrow gauge train for the final five hours to Shimla. I first read about this in Paul Theroux’s The Great Railway Bazaar, which inspired me to add this to my itinerary on my first trip to India. Kalka is just at the edge of the Indian plain, and the train starts a long, slow climb almost as soon as it leaves the station, negotiating tight curves and over a hundred tunnels as it makes its way to Shimla. In the early stages it moves through dense broad-leaved woodland, but these gradually give way to pine forests as the train climbs and, as it approaches Shimla, the pines are interspersed with Deodar cedar trees too. An ironic whoop of delight greeted our first sight of Himalayan Balsam in its natural habitat.

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The “toy train” making its way from Kalka to Shimla, August 2016. The top photograph shows a view of the Himalayan foothills from the train.

Shimla is a glorious, if slightly rundown, anachronism, with buildings evoking the Home Counties side-by-side with modern India. It is not difficult to imagine the mock-Tudor architecture as a backdrop to the shenanigans between colonial service wives and dashing subalterns that Kipling wrote about in Plain Tales From The Hills. The short walk between the Gothic Revival-style Christ Church, at one end of The Mall, the central thoroughfare, and Jakhu Temple, dedicated to the Hindu god Hanuman sets this contrast into perspective. “East is East”, wrote Kipling, “and West is West, and never the twain shall meet.” Shimla, in his time, would have encapsulated that, and some of his short stories touch on the complications that arose when love crossed the cultural and racial divides. In modern Shimla, the East has gradually reasserted itself. We are looking at the reciprocal of “Orientalism”: a mock Tudor building here having the same jolting effect as, maybe, Brighton Pavillon has to a British observer.

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Christ Church and the town library in the centre of Shimla. The statue of Hanuman can be seen just to the left of the church tower.

Life is, of course, rarely that simple. The day before we travelled to Shimla we had visited the tomb of Humayun, the second Moghul emperor, in Delhi. To western eyes, this elegant building, a precursor of the Taj Mahal, fits all of our preconceptions of what an Indian building should look like. But the Moghuls, too, were interlopers, bringing Persian ideas and culture into the sub-continent a couple of centuries before the British arrived. In my travels around the Hindu heartlands of northern India I have seen almost no vernacular architecture that resembled, in any way, these Moghul edifices.  Despite being the quintessence of what we think of as “Indian”, they are no more or less “authentic” than Shimla’s mock Tudor architecture. The difference is that we have enough cues to make the connections at Shimla, but not for the earlier waves of invaders.

Arriving at Persia via Delhi and Shimla does, at least, bring us to the land where Gertrude Bell, feisty north east lass, whatever Werner Herzog and Nicole Kidman would have us believe, made her first explorations. That closes the circle and, as much by luck than judgement, justifies the title of my blog. Which was, you have to admit, too good to waste …

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Humayun’s tomb in Delhi, August 2016.

Return to Pangong Tso

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Pangong Tso, from the Indian shore, looking towards China, July 2015 (photograph: Heathe Kelly).

You may remember that a year ago I wrote some posts about a high altitude lake on the India-China border (see “Subaquatic landscapes in Pangong Tso” and references therein).   This year, Heather made a second trip to Pangong Tso (described here) under the auspices of Indus Experiences and brought me back another sample from the littoral zone.   There was a beautiful thick biofilm here, an unusual bright yellow-brown colour and a jelly-like consistency, but bubbling away as the algae photosynthesised busily.   Once again, local vodka was pressed into service as a preservative and, once again, peering through my microscope a few days later, I could see that the sample was dominated by the same long-stalked Gomphonema species that I recorded a year ago (see “Diatoms from Pangong Tso”). The jelly-like consistency did worry me, as this is not what I would expect of a pure growth of diatoms and I did wonder if there were cyanobacteria growing amongst the diatoms that had not survived the journey home in their marinade of cheap vodka.

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Growths of diatoms (predominately a long-stalked Gomphonema sp) on a boulder in the littoral zone of Pangong Tso, India, July 2015. The right hand image is a close up showing oxygen bubbles being produced by the the jelly-like masses. Photographs: Heather Kelly.

Intriguingly, the Gomphonema seems to occur in two forms: a fatter form, with a width around eight micrometres, and a narrower form, about six micrometres wide. I’ve written before about how diatoms tend to get shorter over time (see “Diminishing with age”). What I did not make clear in this post is that cell breadth tends to stay relatively constant during this process.   This does not happen with every species but it is interesting to see that the fat and narrow forms have overlapping sizes, so it is not a simple matter of the narrow ones being the far end of the size reduction sequence. More work is definitely needed here although, alas, I don’t think Pangong Tso is on the itinerary for next year’s visit to India.

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Gomphonema sp from the littoral zone of Pangong Tso, north India, July 2015.   a. – d. represent the “fat” form; e. – h. are the narrower form(s). Scale bar: 10 micrometres (= 1/100th of a millimetre).