Today, the beginning of the 21st century the global shipping turnover has increased to the extent that almost 80 percent of all cargo shipments are implemented by long-distance vessels. In the context of a rapid development of navigation, some species of marine organisms are frequently transported to different parts of the World Ocean, in many cases located thousands of kilometers away from their original habitat. How do migration processes take place?
Suppose that an oil tanker arrives in a port of destination and discharges oil into an intake structures. After that the tanker becomes much lighter, the center of gravity is displaced, disturbing its seagoing characteristics. Even a small storm can lead to an emergency. To prevent this, each tanker has special ballast tanks filled with outside water. It is a "house" for many marine organisms. Some of them can turn into dangerous "aliens" and colonize new territories. Alexander Zvyagintsev, Dr. Sc. (Biol.), senior research officer of Ecology of Shelf Communities at the Laboratory, RAS FEB Institute of Marine Biology named after A. Zhirmunsky, discusses risks of these processes in an article published in the Far Eastern Scientist newspaper.
About 10 bln tons of ballast water containing over 700 species of aquatic organisms, many of which can become a serious threat to marine ecosystems, economy and even human health are carried annually in the tanks of cargo vessels. Some "alien" species are transported by way of the so-called ship's overgrowth, i.e. animals and plants settle on the underwater parts of the vessel, which is also a serious problem. No customs or quarantine service can stop or somehow limit the flow of underwater migrants. Total global damage by such growth is about USD 50 bln annually.
Dissemination and settlement of new species is one of the reasons of instability of marine ecosystems. If the population of aboriginal species reduces or even disappears, this is an indicator of chan ... Читать далее