The Mediterranean, Black, and Caspian Seas represent three fragmentsof the former Tethys Sea, and are thus of great interest tounderstanding the evolution of the entire region where Eurasia,Africa and the Arabian Peninsula meet. Fishing activity and maritimetraffic through the Dardanelles and Bosporus, and via the Lenin Canalto the Caspian Sea, have greatly intensified. Moreover, all majorEuropean rivers are now linked by canals, meaning that ships cannavigate from the mouth of the Volga to the Baltic, from the Danubeto the Rhine, and from there to all other major European Rivers. Suchan anastomosed system not only allows ships to pass between basins:biota follow in their wake, and thus the Black Sea and Caspian faunaand flora, long sequestered in their closed basins, are suddenlygiven an opportunity to "escape". On the other hand, alien invadersincreasingly find their way to the three seas,as stowaways in ballastwater tanks or attached to the hulls. Some of the newcomers expandedto enormous numbers in the receiving ecosystem, where they may causegreat economic damage. The book provides an up-to-date overview ofthe situation in the Ponto-Caspian with regard to the jelly invasionsthat have been perturbing the local pelagic ecosystems since theearly 1980s, contrasting that with biological invasions elsewhere, totry and identify general underlying principles.
