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Suomen Luonto
English summaries 2/2000

Russian bears rehabilitated
by Staffan Widstrand

pages 4-11

The Pazhitnovs, a family of researchers living in Russiaís Toropets region, have developed the habitat of taking orphaned bear cubs into their care from all over western Russia. Valentin Pazhitnov has cared for over 70 cubs, rehabilitating them for a normal life in the wild. He is quick to point out that he is a bear trainer, not a substitute mother bear. Valentin studiously avoids letting the cubs become permanently attached to a particular human being. During the period when they most easily become attached to a person by imprinting, they are hardly ever allowed to see one.

The Toropets region provides a home for 70-90 bears per every thousand square kilometres of territory. It is twice the size of those areas in Finland and Sweden harbouring the densest populations of brown bears. Annually, some 6-10 % of the population is shot, half of it legally. Bears are also shot at their winter lairs, ensuring that a few cubs are orphaned every year. Many of these end up in the Pazhitnovsí care. Cubs also arrive from as far away as the Urals and Estonia. An effort is made to return cubs, at the age they would normally become independent, to protected areas where there are few, if any, bears already. These attempts have met with a high degree of success, very few of the released bears having later sought the sanctuary of human beings and been shot as a consequence.

Life inside the rock
by Juho Rahkonen

Pages 20-21

Most of Finlandís bedrock is of Precambrian age, consisting of an extremely hard material in which caves rarely form. There are slightly less than a thousand chambers in Finland which can technically be called caves. Such caves are extremely small in comparison to those in central and southern Europe, for instance, the largest Finnish one being the Torhola cave at Lohja. This is slightly over 30 metres in depth and has three room-like chambers.

The caves are used by overwintering moths, flies, gnats, harvestmen and spiders. The haemolymph these invertebrates contain forms substances like glycerol and proteins that act as an antifreeze. The only vertebrates found in the caves are bats, which are able to remain torpid in the constantly cool air throughout the winter. The author has looked for animals in dozens of caves over several winters. He has only found one butterfly species there, and this is the small tortoiseshell (Aglais urticae). A few specimens of two geometer species have also turned up. By far the commonest moth is the herald moth (Scoliopteryx labatrix), dozens of which may hibernate in the space of just a few square metres. All of Finlandís known caves have been discovered by this insect.

Crucian carp survives oxygen-free conditions
by Antti Koli

Pages 22-23

Although the Crucian carp may attain a weight of five kilos in Finland, it generally remains as a finger-length fish dwelling in small pools. It is able to survive on little food and, in winter, in conditions of low oxygen or even of no oxygen at all. Mankind has introduced the Crucian carp into many places since, due to its toughness, it forms an ideal bait for anglers.

The Crucian carp has evolved an enviable capability. In anaerobic conditions where the oxygen has disappeared the fish lives by fermentation, producing alcohol - and making it slightly tipsy. A specimen living in conditions of oxygen depletion may continuously have 0.5 promills (1 promill = 0.1 percent) of alcohol in its bloodstream. Thus, it may not legally drive an automobile, but it would not be risking a stiff prison sentence for being well over the limit.

During fermentation, sugar stored as glycogen ("animal starch") in the liver is broken down. In anaerobic conditions glycogen is transformed into lactic acid, which enzymes then convert into ethanol (ethyl alcohol). Ethanol is released by the liver into the blood stream, and is then excreted through the gills into the surrounding water. In this way, small Crucian carps living in ponds produce thousands of litres of ethanol.

In the realm of ice
by Esko Kuusisto

Pages 24-31

In Finlandís region, there is a lot of ice in the Baltic Sea and on lakes during winter. Even in the mildest winter, it would be possible to build 10,000 Cheops pyramids out of the ice which forms there. Freezing begins in the lakes of the higher fells of northwestern Finland as early as August, and the last to freeze up are the central parts of the Gulf of Finland, Gulf of Bothnia, and the Archipelago Sea - if these freeze at all. Ice crystals appearing on calm water form around particles at the surface. The optical axes of these crystals are vertical. If a breeze tilts the crystals, the axes are tilted, too, and then rod-like crystals form in the ice.

A continuous layer of hard, transparent ice forming at the water surface will as likely as not become covered with snow and this blanket will protect the surface of the ice against extreme cold. Since the water beneath the ice is warmer, it presses upwards against the ice and ice formation is slowed down. This gives rise to a slushy layer which during the next fall in temperature (frost) produces brittle ice made up of tiny crystals. Should freezing be uneven, a layer of slush may become trapped between such ice and the harder ice at the surface.

The freezing of rivers is a far less regimented affair. Especially in rapids the water may lose a lot of its heat, thereby forming super-cooled water. This may either freeze in the water into what is called frazil ice, or form an icy coating on stones on the bed of the rapids. This leads to a rise in the water level, which in turn causes flooding of the land adjacent to the river channel.

The thickness of lake ice in winter has been routinely measured at observation stations for almost a century. Measured at Kilpisjärvi, in Finlandís northwestern corner, the maximum thickness of ice recorded so far has been 114 cm. This was measured on May Day Eve in 1966. In southern Finland, the layer of ice is much thinner, amounting in mild winters to a mere 30-40 cm. In severe winters there will be a layer of ice over 1 metre thick in the Bay of Bothnia. Individual ice masses in pack ice may reach a depth of 10 metres.

Who will benefit from gene foods?
by Juha Valste

Pages 60-61

Gene manipulation, hybrid DNA and transgenic plants and animals came to the publicís attention during the closing stages of the 20th century. Fear has been expressed at the idea of transgenic crop plant varieties and a move has been made to have them banned. However, they appear to have arrived to stay. Researchers consider the new method merely a logical extension of the "old" technique of selective plant breeding. In itself the method is not hazardous, but it can unfortunately also be used for undesirable, dangerous, purposes. Why has no attempt been made to use the hybrid DNA technique for improving the nutritional value of crop plant products and their suitability for human consumption, rather than striving towards resistance to herbicides or insecticides?

The spread of transferred genes into wild populations and their proliferation is extremely improbable. Even were this to occur, the result would not be catastrophic, as Nature herself has been carrying out gene transfers from one species to another for hundreds of millions of years.

At present, only a few giant enterprises operating in the chemicals industry are deriving any benefit from gene foods. These firms have patented genetically modified soybean and maize strains. The companies maintain that farmers and consumers will also benefit, although there is no evidence of this. A very real danger is that the number of cultivated crop plant varieties will be even further reduced, leading to increasingly less genetic variation among them.



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