Anonim

Hunt for invaders
Hidden in the containers of fruit and vegetables, stuffed into the suitcases of unwise tourists, clandestine in the ballast waters of ships. Here's how animals move between continents. Invading new territories and driving out the inhabitants - plants and animals - that populate them.

A Mustang horse. An example of a beneficial animal invasion. In the Americas the horses were brought by the Europeans. Some escaped specimens returned to the wild, giving life to the Mustang breed domesticated later by the Red Indians.
A Mustang horse. An example of a beneficial animal "invasion". In the Americas the horses were brought by the Europeans. Some escaped specimens returned to the wild, giving life to the Mustang breed domesticated later by the Red Indians.

They take planes, ships, trains and cars. They travel thousands of kilometers, flying over oceans, crossing mountains, crossing deserts and, once they reach their destination, they are so good that most of the time they do not go away anymore. They are the "exotic" animals and plants that, brought by man more or less intentionally, change their domicile of origin and colonize new areas permanently. Often causing problems to local biodiversity.
Since the dawn of time, men, in their migrations, have introduced seeds, sprouts and animals brought from the countries of origin and introduced into the conquered ones. A striking example? The horse, brought to the Americas by Spanish conquistadors. Some specimens escaped to Mexico, became wild and reached the grasslands. Where they were tamed again.
How intrusive you are!
Now, however, thanks to the development of communications, commerce and tourism, the number and variety of invaders is reaching guard levels in many countries. Clanders in the cargo of timber and vegetables, like the dangerous African scorpions found at Malpensa this spring, souvenirs in the suitcases of little-known tourists or legal travelers (but not always) destined for exotic pets, the invaders are reaching all the continents.
"The presence of allochthonous animals, that is those that from the evolutionary point of view do not belong to the place where they are, " explains Massimiliano Rocco of the WWF's Traffic office "represents a danger for the biodiversity of the host country and a disruption of the pre-existing balance, which has been created over millions of years of evolution. Their introduction must be monitored and regulated because it causes radical changes, the extinction of endemic species and, not least, the possible spread of diseases and infections ". More than 7, 000 species of animals are at risk, according to recent data presented by IUCN, the International Union for the Conservation of Nature, of which 30% is threatened precisely by the presence of invaders.

Hunt for invaders
Hidden in the containers of fruit and vegetables, stuffed into the suitcases of unwise tourists, clandestine in the ballast waters of ships. Here's how animals move between continents. Invading new territories and driving out the inhabitants - plants and animals - that populate them.

At first sight harmless, actually able to drive the Italian testugini out of their habitat. This is the red-cheeked tortoise.
At first sight harmless, actually able to drive the Italian testugini out of their habitat. This is the red-cheeked tortoise.

Tough life
Not always the alien species reached a new environment manage to survive. Sometimes the climate, the availability of food, the predators block their advance. But in other cases, on the other hand, these travelers overcome resistance and, thanks to great adaptability, successfully settle. When this happens they engage in a ruthless struggle with the locals for the space and food resources and often the employed make a bad end.
This is the case, among many, of the red-cheeked tortoise, originally from the southern United States and brought to Italy as a pet in the seventies. Since then the Trachemys scripta elegans, escaping from aquariums or voluntarily released, lives happily even in our peninsula. At the expense of our local tortoise, now almost extinct.
Failed experiments
The examples do not end there. Thinking of being able to decimate the insects that infested the sugar cane plantations, the Australians in the 30s brought home the fearsome Bufo marinus, a large toad and one of the most poisonous toads, from South America. This "weapon" did not serve its purpose but since then many greedy Bufo snakes are becoming extinct. Why? Because the poison of these amphibians - used by some Amazonian populations to kill their arrowheads - is fatal even for snakes.
But the problem does not only concern animals, plants and their preservation but also our health. Well known and hated by Italian and European allergy sufferers is Ambrosia. Disguised as a harmless map, it arrived from the United States in the 1960s and thanks to the enormous production of pollens (a plant can generate, according to some studies, even a billion), spread along the banks of rivers, in cultivated fields, near the roads. And in the hot season it leaves no way out for the sensitive noses of people with allergies.

Hunt for invaders
Hidden in the containers of fruit and vegetables, stuffed into the suitcases of unwise tourists, clandestine in the ballast waters of ships. Here's how animals move between continents. Invading new territories and driving out the inhabitants - plants and animals - that populate them.

In the ballast waters of merchant ships or as deposits on their hulls. Even so, fish and invertebrates travel around the world.
In the ballast waters of merchant ships or as deposits on their hulls. Even so, fish and invertebrates travel around the world.

Inconvenient travel
Even the seas if they see it ugly. More than 100 species of alien fish have been counted in the Mediterranean. Even more are the molluscs, crustaceans and vegetables.
Many of these animals arrive from the Red Sea through the Suez Canal, others escape from farms, others from aquariums.
Especially the invertebrates reach our seas traveling in the ballast waters of large boats. The ships, in fact, cannot sail empty and must load water in the ports of departure. With water they collect larvae, eggs, spores, small marine animals that, once at their destination, are unloaded to make room for the goods. This means that typical organisms of the Chinese or African seas arrive in the Mediterranean, altering the composition of flora and fauna.
At the table with the invader
But the gluttony of Italian gourmets for exotic products has also played its part. This is the case of the plump and succulent Filipino clam (Tapes philippinarum) which, introduced in the Mediterranean in the 70s for breeding, has almost made a clean sweep of our local clam.
And the release of the film "Finding Nemo" is bearing fruit: almost twenty species of tropical fish are reported off the coast of Florida. It is believed that, by emulating the cartoon, many children have freed their aquarium guests at sea, including the poisonous lionfish.
Biodiversity at risk
"The causes of the globalization of biodiversity are manifold and for the last 50 years the problem has become global, " explains Franco Andaloro, of the ICRAM, a central institute for scientific and technological research applied to the sea "to stem the entry into our sea of alien species it is necessary to monitor their evolution in the new environment, develop strategies and raise awareness among fishermen and public opinion ".
In a few months the Atlas of Alien Species will be ready, the first made by a Mediterranean country, which the ICRAM has prepared at the request of the Ministry of the Environment. "It will help us understand and safeguard our habitat, " concludes Andaloro.
It's nice to see tropical little fish splashing around in the waters of the Tyrrhenian Sea, being able to buy colorful exotic parrots that often don't even speak, take home from a trip overseas small seeds to sprout on the balcony or be able to eat delicacies from distant countries. But the problem is that then sending them home is really difficult.

Paola Grimaldi