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Section: Biology
Multitudinous Whisper of Uzon

Multitudinous Whisper of Uzon

Uzon…the multitudinous whisper of this word makes you think of tiny jets of vapor and gas, hissing and whistling, gushing out of the earth's interior. The caldera of this dormant volcano is like a cup buried among cold, rough mountains and boasting of its bright colors, warms springs and roaming bears. Extreme tourists from all over the world are ready to pay good money and spend days waiting for a helicopter in order to make it to this hard-to-reach and luring corner of Kamchatka. This fantastic world lost at the ends of the earth, however, is not only a Mecca for lovers of nature but kind of a natural laboratory that attracts scientists anxious to get an insight into the origin of life

Volcanoes – a most impressive manifestation of mighty natural powers – always urge us to find out how this natural laboratory works and where the not yet fully studied processes of liberation and transformation of the earth’s interior energy and substance take place.

Being close to the crater of an active volcano is not safe though: the intensity of its eruption is unpredictable and lava temperature exceeds 1000 °С; poisonous gases and hot ash may be dejected. Dormant volcanoes are a different story: their magma chambers are hot enough to heat the peripheral areas and hydrothermal systems for tens of thousands and even millions of years to come. These volcanoes are frequented by volcanologists, geologists, and biologists.

A remarkable modern ore forming hydrothermal system of our planet is the caldera of dormant volcano Uzon located in the active volcano belt of Kamchatka’s Eastern volcanic zone. The distance between it and Petropavlovsk-Kamchatsky is only 80 kilometers but getting there is not easy…

Kamchatka’s oasis

First publications about the hot springs of Uzon date back to the expeditions led by Carl von Ditmar organized by the Russian Academy of Sciences in 1851—1855. The Uzon caldera impressed Ditmar deeply: “We stopped at the edge of an old colossal crater. And down there, in the domain of snow devoid of any vegetation, like a miracle, there lay a huge trough smiling to us from its depth with a riot of lush luxurious vegetation.”

From a helicopter window, the caldera looks like a gigantic magic carpet 9 x 12 km in area, with blue saucers of numberless large and small lakes. Vapor plumes, like grey-bearded genii, tower above the simmering springs. Snaking all around the valley are hot water streams of every spectrum color thanks to additions of mineral salts and colonies of bacteria and weeds.

The caldera is situated in the western part of the Uzon-Geyser volcano-tectonic depression named after its two constituent structures (the Geyser Valley was discovered a hundred years after Ditmar’s expedition).

CALDERA (from the Spanish caldero, a “big pot”) is a depression with steep flanges and comparatively even bottom that has formed as a result of the volcano’s peak falling down as a consequence of a powerful explosion or, more typically, in consequence of the top collapsing or subsiding under the erupted masses. A caldera is distinguished from a crater by its origin and larger size (minimum of 10—15 km across). Calderas are often taken by lakes; their characteristic features are fumaroles and mud springs.
FUMAROLE (from the Italian fumo, “smoke”) is a source of hot gases in craters and on volcano slopes, as well as in the crust of cooling down lava flows. As a rule, thick vapor curls above large fumaroles because magma contains a fair amount of water. Apart from water, fumaroles discharge gases dissolved in magma: carbon dioxide, sulfur oxides, sulfuretted hydrogen, halogen hydrogen, etc. Fumarole smoke can be dangerous for man but for some bacterium species they are nutritious.
MUD SPRING is an outlet of subterranean water from aquifer rock in the form of a concentrated jet rising above the ground or the bottom of a water basin

The Uzon caldera formed in ancient times. About 370,000—750,000 years ago, in the place of the modern depression there was a large shield volcano. In the second half of mid-Pleistocene, as a result of an eruption, a huge crater appeared in the eastern part of the volcanic structure, which generated mighty flows of glassy material, acid in composition. The lava that remained in the crater foamed to make pumice deposits in the east of the caldera.

The caldera acquired its up-to-date look about 40,000 years ago after a series of powerful faults and expansions.

At the bottom of the hot cup

The caldera’s bottom is a fairly flat depression 650 meters above the sea level. Its black basalt flanges go up another 500—950 meters. Far in the south the volcanic massif of Zubchatka shows blue. There is a true sign: if its peaky ridge is not overcast, the weather will remain good.

The caldera is cut across with a number of tectonic faults, through which hot solutions come up to the surface. Their warmth heats the neighboring rocks, which is why the narrow strip of the caldera (maximum 200—400 m wide and 1.3—3.0 km long) has virtually no snow. Lakes filled with warm bluish and greenish water attract ducks, which often stay the winter here.

In the heated areas of the caldera called thermal fields there are hundreds of vapor and gas punctures, no-drain funnels, mud pools and mud springs with seething water. The total thermal output from natural thermophores amounts to 70,000 kilocalories per second. Water temperature in large springs reaches 96 °С, which is the boiling point at the height of 650 m. The springs steam profusely before the bad weather preceded by lower atmospheric pressure. You can hear the simmering of small crater puddles and hooting of fountains periodically gushing with water or watery mud.

In the south, the steamy lowland borders on spongy, boggy tundra with patches of dry glades thickly overgrown with berries: bilberries, honeysuckles and mossberries. In the east and north-east, the caldera’s bottom is somewhat elevated. Here and on low hills found in other parts of the caldera grow evergreen creeping cedars. In the center of the cup there are clusters of straight-stemmed birch trees and Kamchatka grayish rock birches with crooked chalk-stone branches.

The caldera’s northern sector has five thermal fields. The largest in area and thermal output is Vostochnoye, stretching 1.5 km in latitude. It is a favorite research spot of volcanologists and biologists. Their retreat is right here, next to a brook. The old camp cabin fell apart a few years ago, and a new one was built in its place.

Thermal field Vostochnoye

The Vostochnoye thermal field starts with Lake Bannoye. Its deep cup is filled with cloudy grayish-whitish water of a very comfortable temperature (39—45 °С). Thanks to radon found in the lake, bathing in it calms down the nervous system: the tiredness you feel after a long day goes away immediately, giving way to pleasant languor.

The lake’s configuration and character of bank deposits suggest that the lake funnel derived from an explosion. In July 1989 a new explosion occurred in Lake Bannoye. It has turned out that the lake has a false bottom at a depth of 32 m, which is a crust of molten native sulfur.

In its central part, the field is a flat depression covered with fine gravel of dark color – debris of clinker, basalt, and pumice. A great many large and small funnels are simmering with hot water and mud, a suspension of clayey substances. Most funnels have no drain; though the water temperature in them does not exceed 70—80 °С, they are seething because of volcanic gassing.

Next to the funnels with clear water there are mud springs with cloudy water and mud pools. The funnels sometimes join to form a system of “saucers” divided by narrow bridges. The ground in these places is infirm, and just a few inches deep the temperature goes above 100 °С. Careless travelers can literally get into hot water (hot clay, to be more exact): it is very difficult to get out, and the heat quickly becomes unbearable despite the rubber boots. A firm rule for researchers here is to wear high rubber boots in a large size so that you can take them off quickly.

The northern flange of the thermal field is a high terrace overgrown with berries. Next to the thermal field, the flange is divided into sloping hills, whose southern slopes have no vegetation. Their wet clayey sides glittering in the sun show multi-color streaks and rings with holes in the center through which the solutions transpired. There are some deep (1.5—2.0 meter) depressions, where thick clayey mass mixed by gases is seething and champing.

On elevated areas you can see beds of tuff having a rich content of yellow-green crystal sulfur: sulfur hillocks. Gas and vapor jets with sulfuretted hydrogen used to gush out here, and you can still come across them – they form sort of peculiar towers and yellowish-white sulfur sinters. Free of any vegetation, the bald area in the center of the thermal field is speckled with countless large and small funnels, saucer-shaped mud springs, and mud pools. Outstanding is the enormous steaming surface of Chloride Lake, named after the chloride-sodium composition of its waters.

In the western part of the Vostochnoye thermal field there is an oil area. If you dig a hole 20—30 cm deep, it will be filled with hot water with oily drops on the surface. The Oil Area can be traced if you follow the tracks of bears: the animals are considered to get rid of importunate parasites by rolling in on the oil-bearing ground.

Duck flocks have taken a fancy to warm Lake Utinoye (“Duck Lake”), which does not freeze over in the winter. It hides under a hill overgrown with tall birches, quite shapely for this locality. Ever-green branches of creeping cedar overhanging the water glass themselves in the calm expanse of the lake, making it look greenish and witchingly mysterious...

Life in boiling water

The problem of life origin and its further evolution on the Earth remains topical in academic circles.

As is known, in its early age our planet was a fiery object, gradually cooling down. Bearing in mind potential “eternity” of the Earth’s first inhabitants, microorganisms, which reproduce by replication, there is no doubt that studies into these “living fossils” can open up new aspects of life evolution. Positively, such fossils are the now existing thermophile bacteria and archaeobacteria, a living memory of our planet’s hot past.

It should be noted that the phenomenon of thermophilia is inherent exclusively to the lower monads. If a systematic group has a thermophilic genus, in all likelihood, it will be closest to the “progenitors”. Kamchatka and one of its pearls, the Uzon caldera, is a unique place for carrying out this kind of research.


Bears usually come here in April and May. Everything around is still covered with snow – and the caldera is green with grass, a deli at the time of spring short rations.
The animals take pleasure in strolling, in a fitting manner, around the warm Uzon ground. She-bears produce offspring in January and in spring bring their tiny cubs, normally one or two, from the dens to the wide world. On Uzon they feel perfectly safe.
If a man approaches, the she-bear takes the cubs away without hurry to keep a distance she considers to be safe. But woe betides you if you happen to cross this invisible borderline: the bear may think that the situation is dangerous for her kids – and despite the seeming clumsiness bears can easily make 55 km/hour.
So it is not advisable to come close to the bears peacefully enjoying berries. Professional photographers who publish snapshots of bears taken from a very short distance have secrets of their own. As a rule, their models are he-bears totally carried away by fishing. Besides, the photographer’s safety is insured by a reserve worker standing nearby and armed with a rifle. Amateur photographers act at their own risk. We came across a family of photographers: one of them was taking photos of a he-bear while the other had at the ready a deterrent gas cylinder the size of an automobile fire extinguisher...
The maximum number of bears we managed to observe in the Uzon caldera was eleven animals including cubs. A mother bear looks after the young two years. After that she leaves them in the “great world”, and the cycle repeats.
There are exceptions to this rule, however: last year we saw on Uzon a friend of ours, a young bear who has been living there for a third year, nicknamed Sloppy for his untidy looks and nasty manners. She-bears show no respect toward him either and box his ears whenever they have a chance. Sloppy runs away from furious mothers right on the thermal fields, completely ignoring the hot puddles.
In principle, Kamchatka bears are very peaceful, which is not a surprise: they are the strongest among the local fauna and have no natural enemies. Only meeting the animals unexpectedly can be dangerous as bears may consider that you are trespassing on their territory or interfering with their activities – fishing or an afternoon nap. Therefore, when walking among tall creeping cedars, it is wise to make your presence known in advance by whistling, singing, or making noise.
Bears feeding in the multi-color bilberry-cowberry-mossberry tundra have become an indispensable part of the caldera landscape. People try not to bother them, and the animals pay them back with condescending indifference, as becomes the masters of Uzon.

Hot waters of the springs saturated with volcanic gases are a habitat of several specific microorganisms. Importantly, under certain environmental conditions microorganisms can lapse into a state similar to anabiosis, and their vital functions can pause for hundred thousands and even million years! These weightless creatures can be carried by wind any distance. As a result, emergence of new or going back to the former environmental conditions can trigger a meteoric growth of microbe communities. For instance, the cinder belched by volcanoes remains sterile for a very short period after the eruption: solitary microbes can be found there right after the first rain!

The oligonucleotide probes purpose designed at the Institute of Chemical Biology and Fundamental Medicine, SB RAS, which allow to assess how closely “related” the bacteria are based on their ribosome protein gene (16S рРНК), have made it possible to evaluate quickly the diversity of microorganisms without conventional cultivating. Moreover, similar techniques can help to identify organisms having new important properties – for example, the ability to produce heat-stable enzymes, which are currently widely used in biotechnologies.

Studies of microorganisms annually collected on Uzon have revealed at least two tendencies. First, the caldera’s thermophilic microbe communities alter depending on variations in the environment; new taxons are being routinely discovered. Second, there exists a specific set, not of organisms, but of relic gene systems that constantly circulate in these peculiar conditions and are detected with one or another bacterial strain.

And the smell of sulfur...

When you first come to Uzon, you are petrified by the peculiar smell of sulfuretted hydrogen, which at times is so strong that some travelers cannot sleep a few nights. Uzon is a great test site for investigating the circulation of sulfur as a necessary element of the living substance.

Sulfur has variable basicity, which allows it to form a great variety of compounds. Cyclic sulfur conversions occur mainly due to the reactions of oxidization and deoxidization. However, if the former can be purely “chemical”, the latter typically require bacteria. From the systematic point of view, the group of colorless sulfur bacteria united by physiological indicators is extremely diverse and not all the species and even genera described can be considered firmly established.

In the last decades the sulfur natural cycle has experienced an increasingly strong anthropogenic impact, which has led to accumulation of toxic sulfur compounds and is upsetting the sulfur natural balance. Sulfur bacteria are not just an invaluable material for evolution studies but the only factor capable of completing the cycle of this crucially important chemical element.

There are lots of sulfur bacteria on Uzon: small as they are, their mass clusters in the form of films and tousles are very well visible in the transparent water of hot rooks.

The caldera’s hot springs abound in cyanobacteria, the first photosynthesizing organisms on earth. These lower monads, which are loosely called blue and green seaweeds, produce oxygen when exposed to light, similarly to higher plants. On Uzon they cover the surface of thermal springs with a thin film, serving as sort of filters that prevent certain gases (like methane and carbon dioxide) from getting into the atmosphere.

Today, in the caldera of Uzon volcano nine benchmark sites have been selected to study the biodiversity of its microscopic inhabitants. Scientists are looking forward to finding not just new bacteria – “helpers” of mankind – but also evidence of the most ancient steps in the birth and evolution of life on earth.

One has only to step on the hot ground of this cooling volcano and see powerful vapor columns rising up above hot springs and geysers, spluttering mud pools, and multi-color rooks rich in minerals amid the bright carpet of erupted rocks to believe that this is the way our planet looked at its birth.

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The expedition was partly financed through the projects of SB RAS Presidium
The authors are grateful to the authorities of the Kronotsky State Biospheric Reserve and personally T. I. Shpilenok for assistance in handling administrative and organizational matters

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