Introduction of new species

The list of species introduced to the Baltic Sea already, for example, is very big (about 70 species), and in many cases the new comers replace the entire bottom communities, like the west-Atlantic polychaete species Marenzelleria viridis (www.ku.lt/nemo/mainnemo.htm )

• Artificial introduction

  Sometime people introduce new species to habitats, or reintroduce species to the place where it was common in previous time, in order to restore natural values or to gain commercial profit.

  In the period of 1980-1985, few thousands of king-crab Paralithodes camtchatica, normally inhabiting the northern part of the Pacific ocean, were transported to Barents Sea. About 15 years passed and now Paralithodes is common along the Norvegian and Russian shore of Kola peninsula. Last year it was found in the White sea. In 2002 Norway and Russia decided to open quota for fishery, but there are still very limited data how this great crab affects the bottom communities of the Barents Sea. According to recent news, after few years of tre very successful breeding, the abundance of Paralithodes along the Shoreline of the Kola penincula is so high, that the populations of many invertebtrate species like sea-stars, were seriously treated (just eaten). (Fyodorov, 2002).

• Occasional introduction

  However, more often it happens that species are introduced unconsciously or by accident. Effects on the local ecosystem may be considerable.

  Tankers, when navigating without cargo (oil), have to fill their tanks by the sea water. It means, that they transport billions of cubic meters of sea water over thousands of miles. In the particular case of tanker navigation by channels and rivers from Caspian Sea to the Black Sea and back, scientists warned authorities, because of the danger of introduction of Mnemiopsis to the very sensitive ecosystem of the Caspian sea, but nothing was regulated (www.caspinfo.ru/library/bulletin/caspvk/1_33.html).

  Another example is that of Caulerpa algae introduced to the Mediterranean by a unique occasion. One specimen of Caulerpa living in a sea aquarium in Monaco was thrown into the sea. Now this species is occupying large areas through the coast of France and Italy. www.coastalguide.org/eco/index.html