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ALIEH SPECIES: ECOLOGICAL THREAT

Дата публикации: 12 ноября 2021
Автор(ы): Yuri DGEBUADZE
Публикатор: Научная библиотека Порталус
Рубрика: ЭКОЛОГИЯ
Источник: (c) Science in Russia, №6, 2013, C.95-102
Номер публикации: №1636709009


Yuri DGEBUADZE, (c)

by Acad. Yuri DGEBUADZE, Deputy Director for Science, RAS Institute of Environmental Problems and Evolution named after A. Severtsov

 

Today living organisms invading ecosystems located beyond boundaries of their natural habitats or biological invasions of alien species are a global problem. Aliens from other continents-whether viruses, bacteria, fungi, algae, mosses, ferns, higher plants, invertebrates, fishes, reptiles, birds, and mammals-can destroy local ecosystems and damage aboriginal species.

 

RECENT BIOLOGICAL INVASIONS IN RUSSIA

 

Invasion of alien species (or species-settlers) is a continuous process; but if in the past, animals and plants migrated by natural reasons associated with global geological and climatic transformations of the Earth; in the last 400-500 years this process was directly or indirectly accelerated by human activity. A well-known example of natural biological invasion is an interchange of representatives of the terrestrial fauna between Eurasia and America through Beringia, which had a direct effect on the territory of the present-day Russia. Migration processes have been and are still registered in aquatic ecosystems in the watershed areas of large river systems that differ significantly by genesis and composition of fauna. In particular, similarity of the fish fauna of the upper reaches of the rivers of Altai, Southern Siberia and Mongolia proves contacts between water basins of the Pacific and Arctic oceans and the Central Asian closed drainage basin. Nevertheless, by the 18th century, when a serious scientific inventory of the flora and fauna of Russia was launched, most natural habitats had already been formed. At the same time, the anthropogenic changes in the environment and a number of aboriginal species accompanied by invasion of alien species had also begun.

 
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Distribution of alien species of fish in the river basins of Russia. (Ratio to the general number of species.)

 

Even though the greater part of our country is characterized by moderate and cold climate, and the completed studies showed that all alien species migrate preferably to the southern regions, there is a series of circumstances accelerating invasion processes in Russia too. First of all, it is a vast territory covering several biogeographical zones. In addition to active freight traffic and absence of controlled migration of living organisms, a deliberate introduction ("acclimatization") policy was implemented in the USSR and later in Russia to improve productivity of ecosystems and assortment of obtained products, let alone underdeveloped appropriate legislation.

 

The analysis of periodicals published by the USSR AS and the RAS carried out in the late 1990s revealed over 500 alien animal species living in the RF territory. In fact, it is an underestimation, if we take into account a general slowdown of biodiversity studies registered in the late 20th century.

 

The multiyear deliberate introduction of alien species carried out by public organizations and individuals affected natural biological diversity. This way of penetration of settlers have led to a situation when 1,150 alien plant species (earlier all of them prevailed beyond the boundaries of the region, not expanded their natural habitats within it), 191 species of herbivorous insects (most of them are pests destroying agricultural, forest and park plantations), 59 fish species and 62 species of mammals are met only in the European part of Russia.

 

By the late 20th century, a number of invasion corridors was formed in Russia giving way to alien species colonizing a new territory. As for land organisms (first of all plants and insects), migration routes are associated with transportation of agricultural products and wood; as for aquatic organisms, penetration of alien species is attributed to basins of big rivers, development of hydropower plants and navigation activities. As for the latter, a special role is attributed to interconnected channels. Migration of aquatic organisms through invasion corridors is also promoted by newly formed water basins allowing limnophilous organisms (adapted to dead waters of the lake type) to gradually conquer vast territories.

 

Today we can definitely state that there are 4 large transcontinental water invasion corridors in our country: Black Sea-Caspian-the Volga basin, Ob-Irtysh, Lake Baikal-Yenisei, and Amur rivers. It is quite interesting that the share of alien species there makes up at least 20 percent, which is clearly seen in fish species.

 

Since a majority of large rivers in Russia flow from north to south (the Volga) or from south to north (the Ob, Yenisei, Lena), global climatic changes of the recent decades (warming) have contributed a lot to the process of migration of alien species of aquatic organisms. In the Volga basin, a period of creation of large water bodies was accompanied by deliberate introduction of aquatic organisms. In the 1940s-1980s, scientists made attempts to introduce 18 fish species to the

 
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Volga--whitefish from north-west of Russia, carps from the Amur, North American freshwater catfishes, catastomides, and cyprinidonts from North America. After creation and eutrophication of water bodies, the invasion process sharply accelerated, partly on account of self-settlement of aquatic organisms. In the 1940s-1970s, most water bodies on the Volga were conquered by lake dwellers typical of the north-west of Russia--European cisco and smelt. Then, in the late 20th century, 7 species of sculpins, Black Sea pipefish and Black-Caspian Sea sprat set out on their way from south to north (from the Sea of Azov through the Volga-Don Channel and from the Caspian Sea through the Volga). In this situation, younger waterbodies turned out more sensitive to the invasion of alien species.

 

It is absolutely clear that the climatic factor stimulates invasion of land animals too. For example, the muskrat

 
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was introduced to our country in the early years of the last century but, encouraged by global warming, continued expanding its habitat northwards. It was initially introduced as a hunting species (but the idea fell short of expectations). The muskrat changed its integument (aquatic and semi-aquatic) and produced significant pressure on bivalves. In some areas, the muskrat is a "reservoir" and vector of diseases.

 

In case of mammals, the invasion of alien species has another highly critical aspect as a part of them are synanthropic animals (live together with humans), and they settle not only near built-up and agricultural areas, but also in natural aboriginal ecosystems. For example, in the late 20th century the brown rat from China (the commonly spread species) expanded its habitat to human settlements. In the past, rats proved to be a cause of spreading plague or Black Death all over the world and besides, every year they consume up to 20 percent of global food stocks.

 

In addition, for many years there were efforts to introduce domesticated and wild reindeer to the northeastern regions of Russia. In the early 1920s, the species was also brought to the Wrangel Island. The animals soon settled there and lived as a half-free species. The Wrangel Island is the only nesting place of the snow goose, a rare disappearing species. Several years after the introduction of the reindeer, the number of nesting snow geese began declining. From 1960 to 1973 their population reduced to 6,000 pairs (from 400,000), which was first of all caused by the invasion of alien species--a reindeer that seriously damaged nesting areas.

 

Unfortunately, none of these dismal results of introduction of alien species taught "improvers of nature"

 
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anything. In 2003, the Kamchatka marmot was introduced to the Paramushir Island, while in 2005 the reindeer was introduced to the Shumsha Island of the Greater Kuril Range. It is necessary to point out that in accordance with Article 8(h) of the Convention on Biological Diversity which Russia joined in 1992 in Rio de Janeiro, the member states should "prevent introduction, control or eliminate alien species, which threaten aboriginal ecosystems, habitats or species". It is commonly known in the expert society that island ecosystems are especially sensitive to any exposure, including invasion of alien species. Taking into account the fact that the above-mentioned islands are not inhabited by man, it is hardly possible to consider introduction of new species rational.

 

One should always remember that introduction of an alien species is a serious intervention in nature, the unfavorable results of which are hard to correct. In many cases, migrating species in contact with aboriginal populations essentially change the biocenosis that leads to large-scale environmental, economic, and social aftereffects.

 

It is worth saying that national scientists have repeatedly emphasized the necessity to be more careful while selecting new species to be introduced. Nevertheless, some specialists kept promoting the idea of setting animals in a new place even after publication in the early 1960s of a series of scientific papers dedicated to a detailed review of the results of the so-called "acclimatization" works (unfortunate name of deliberate introduction of new species) proving uselessness and even harmfulness of many of them, while others began to sound the alarm. Thus, after analyzing the results of numerous introductions of game species to the territory of the USSR, Moscow University Professor Vladimir Geptner concluded that "most of them were not successful or almost useless and had a small or doubtful economic effect". The famous zoologist Andrei Nasimovich was also very reasonable expressing his ideas: "It is more efficient to rehabilitate local species than introduce species from neighboring habitats with different natural conditions."

 

There is a widely accepted standpoint that extensive exploitation of natural resources (in particular, fish reserves) is not a problem, since you can increase the production efficiency by way of introduction of alien species. With this approach in mind, national specialists have supported large-scale dissemination of aquatic organisms for many years.

 

However, even a superficial analysis of these activities shows: the vast majority of deliberate introductions of alien species should be recognized as unsuccessful. The preliminary analysis of environmental conditions in the regions of potential introduction and special scientific studies turned out to be of no use: new species fail to naturalize or affect the environment in an unexpected way. For example, according to the analysis of data on introduction offish species to the territory of the USSR and later Russia carried out by the biologist Yevgeny Burmakin, despite all efforts (1,398 water bodies were covered), the results achieved are rather unsuccessful: the biological effect was registered only in 12 percent of water bodies, introduced species survived only in 15 percent of water bodies, 32 percent of introduction efforts failed, in 41 percent of cases no effect was registered. In the late 20th century, the long introduction experiments carried out in Russia did not show expected results (poor production efficiency) or resulted in an uncontrolled settlement of species in adjacent water bodies.

 

In recent years, freight transportation, first of all sea traffic, has intensified invasion processes. For example, the analysis of ballast waters of ships carried out in many ports throughout the world showed: over 7,000 living bodies are transported daily in ballast waters. As a result of this occasional transportation, over 150 alien species have migrated to the Azov-Black-Sea Basin and about 60 alien species to the Caspian Sea. Many of them produced a great effect on the ecosystems of our southern seas. For example, the Gastropoda class of conch shell, one of the oldest marine settlers. Everybody who visited the Black Sea could have seen this nice shell. After it settled there 50 years ago, it has already experienced two population peaks and annihilated a great number of mussels and oysters that are target species and important elements of natural associations.

 

Another example of destructive invasion is the warty comb jelly. This small jelly-body invertebrate 10-12 cm long got into the Azov-Black-Sea Basin in the early 1980s supposedly with ballast waters. It is originally from North America. In a decade, by the late 1980s, the warty comb jelly increased in number--its biomass in samples was 12-13 kg per 1 m3. The sea was overcrowd-

 
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ed with this species. Living in a water column, it consumes marine invertebrates and plankton organisms. The size range of these organisms is large: from 10 mc to 1.5 cm. Rather quickly, this species eliminated food reserves originally consumed by pelagic fish. Moreover, it annihilated and reduced the population of shell-fish, inhabiting the pelagic zone. As a result of its settlement, fish catch in the Black Sea reduced sixfold, which affected the Clupeonella genus and consequently our fishermen suffering great economic and social losses. According to some assessments, the damage from the invasion of this species to the Black Sea was up to 250 mln USD a year. In 1999, it was registered in the Caspian Sea, presumably taken there with ballast waters. Finally, the volumes offish catch rapidly reduced there too.

 

STUDIES OF ALIEN SPECIES IN RUSSIA

 

Russian biologists focused on the problem of migration of alien species, as it is understood nowadays, only in the early 1990s, even though some aspects of the invasion problem is being studied in our country over a century.

 

First, scientific works were aimed to identify living organisms useful for man, which could be brought from remote regions and naturalized in new habitats. They studied both the species capable of increasing productivity of aboriginal ecosystems and expand the assortment of recourses used by people and the species that could help in pest control. Without assessing the expediency of these studies, we are sure that the obtained scientific results were useful for understanding the invasion process, especially for assessing adaptation potentialities of alien species. Moreover, in the course of these studies, scientists thoroughly described phases and terms of naturalization of alien species after their deliberate introduction. Then, scientists analyzed results of their continuous introduction activities and prepared summaries on a number of alien species.

 

There were published monographs on the Colorado potato beetle, zebra mussel, muskrat, peled, musk ox and some other alien species in the USSR and later in Russia. Some authors made attempts to assess the effect produced by alien species on recipient ecosystems.

 

In the late 20th-early 21st centuries the invasion process intensified in Russia. Scientific research in this field of knowledge became more active. There appeared scientific works describing in detail invasion processes, impact of certain alien species on the aboriginal species and ecosystems. In particular, you can get familiarized with the results of research works dedicated to the Canadian pondweed that was spreading almost throughout Russia for a century, the warty comb jelly, maxillopods, Polychaeta that migrated to the Baltic Sea, Baikal amphipods introduced to the fresh waters in the northwest of Russia, the Kamchatka crab introduced to the Barents Sea, the goby fish migrated to the European part of Russia, Western Siberia and Baikal, the Black and Caspian sea Clupeonella genus that settled in the Volga reservoirs, the smelt that was introduced to some lakes and reservoirs in the north-western part of the country, the European beaver reintroduced and colonizing almost the whole of Russia.

 
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It was found that disturbed ecosystems are most sensitive to invasions. In most cases, such disbalance is caused by human activity, which results in liquidation or transformation of habitats and overuse of certain biological resources. Scientists also found a connection between invasion processes and global climatic changes.

 

Identification of the main transit invasion routes is a significant finding of the recent years. The most important progress has been achieved in identifying ways of penetration of weed-infested plants and pests into Russia. Most of them are connected with the traffic of agricultural products. Augmented in the last 20-30 years, migration of aquatic organisms is caused by construction of channels, dams and intensification of freight transportation. Scientists have launched monitoring of aquatic organisms migrating through the Black Sea-Caspian-Volga transit way, important for the European part of Russia, and also of organisms brought by ballast waters of ships.

 

Speaking of other undisputed achievements of national science in the field of invasions, it is worth mentioning years of complex studies carrried out in the Karelian lake of Syamozero, which showed that only one new species of fish (smelt) is able to transform the whole nutritive structure of a water ecosystem. Transformations registered in the Syamozero have been triggered by smelt that turned into a dominating species in the recipient ecosystem.

 

The ecosystems suffer greater damage due to habitat-forming activities of another key species--the European beaver. By the early 20th century it almost disappeared in Russia. However, after an intense repeated introduction, which began in the USSR in the 1920s, and self-dissemination, the population of this animal became relatively big. At present, it got back its initial habitat. In case of the European beaver, taking into account large-scale transformations of ecosystems caused by climatic and anthropogenic activities, and irreversible nature of such transformations, it is necessary to say that reintroductions (regeneration of extinct populations in their natural habitats) are, in fact, invasions. The "old" species becomes alien to its original, but already transformed ecosystem. Settling of the European beaver in a new place changed seriously food chains of small rivers, as well proved on the example of upper reaches of the Volga River.

 

What was going on with the European beaver proves that reintroduction should be carried out very carefully, since, as a rule, the ecosystems receiving reintroduced species are already transformed and it will be very difficult to forecast the aftereffects of occurrence of "visitors from the past".

 

In recent years scientists have achieved a significant progress in modelling the invasion process. On the example of zooplankton associations as prototypes and certain parameters of real species it was established that the forecasting of a success of introduction of alien species is reliable only if the most important factors (excessive food reserves, injurious exploitation of natural resources and competition), influencing the results of competition between the aboriginal and introduced species, are taken into account. The models show that there is no interrelation between the biological diversity of an association and its resistance to the introduced species, while forecasts of the results of the invasion process require a detailed biological and mathematical analysis of each particular situation.

 

Recently, the first attempts to make an inventory of alien species of Russia completed with the results open for researchers and representatives of regulatory bodies. The databases on the key groups of organisms for regions (European part of Russia, basins of the Baltic and Far-Eastern seas, the Volga River) were created. Speaking of the Internet sources on the problem of alien species open to the public, we should mention creation of a targeted website "Alien Species in the Territory of Russia" (website of the RAS Institute of Environmental Problems and Evolution named after A. Severtsov http://www.sevin.ru). Its principal goals and tasks comprise: provision of information to the public, legislative bodies and scientific association on the problem of invasion of alien organisms; coordination of activities carried out by different specialists and institutions within the framework of one of the scientific research centers on invasion studies; creation of a single information space on the problem of invasion of alien species to the territories and water bodies of Russia.

 

Thanks to the commitment of the RAS specialists, higher education institutions, a number of specialized institutes, the problem of introduction of alien species in the RF territory has come into the center of scientific and public attention. For a short time, within the framework of a number of projects (including programs launched by the RAS Presidium, the Russian Foundation of Fundamental Research and the RF Ministry of Education and Science), the scientists identified the

 
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main invasion routes, created databases on alien species, assessed their impact on aboriginal ecosystems, worked out a monitoring system and, what is most important, formed a network of invasion monitoring stations.

 

All-Russia and international conferences held recently contributed a lot to the development of research on biological invasions of alien species. Many of these conferences resulted in the publication of thematic collections and monographs. The electronic magazine The Russian Journal on Biological Invasions is being published since 2008, in recent years an English version too.

 

However, there are a lot of things to do, since the framework of invasion studies is constantly expanding. In this respect we can point out the following advanced research works on the invasion of alien species: adaptation mechanisms of alien species and aboriginal species affected by invasion; vulnerability of ecosystems to invasions of alien species; ecological parameters of species after successful introduction; experimental and model studies of a trophic relations (competition, predator-victim, host-parasite) of an introduced species in the recipient ecosystem; multidisciplinary approach to studies of ecological after-effects of introduction of alien species.

 

At present, the most pressing problem is coordination of all research groups dealing with the problem of invasion of alien species organized within the RAS structure and other institutions. The section Invasions of Alien Species of the RAS Committee for Preservation of Biological Diversity established in 2002 is of great help to accelerate this process. The section members organized 3 international conferences and a round table, two collections of scientific articles have been published. The publication of The Alien Species of Russia book series is already in progress, five volumes of which have already been published: V. Chachshukhin, The Musk Ox: Reasons and Aftereffects of Biological Invasion; V. Chachshukhin, The American Mink; V. Bobrov, A. Varshavsky, L. Khlyap, The Alien Species of Mammals in the Ecosystems of Russia, Yu. Vinogradova, S. Mayorov, L. Khorun, The Black Book of Russia, V. Maslyakov, S. Izhevsky, The Invasions of Herbivorous Insects to the European Part of Russia.

 

Let us hope that the results of scientific studies will be applied in practice to forecast, control and prevent aftereffects of invasion of alien species. Otherwise, environmental safety of the country is in serious danger.

 

Illustrations supplied by the author

Опубликовано на Порталусе 12 ноября 2021 года

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