Adaptive strategies of Mnemiopsis leidyi A. Agassiz 1865 in different environments of the Eurasian seas.

Comprehensive synthesis of the harmful invader ctenophore Mnemiopsis leidyi adaptive strategies and its validation as of a single polymorphic species has been presented. Its high morphological and physiological variability in different environments were demonstrated. M. leidyi being native for eastern coasts of Americas, since the early 1980s began to invade in the Eurasian seas and now it is recorded in a wide range of recipient habitats. Analysis of M. leidyi morphological and eco-physiological variability, phenology and rate of reproduction was performed for different environments based on author's data and published sources. Prominent morphological features of M. leidyi, previously used to subdivide it in three species, in fact are a phenotypical variability, associated with environmental conditions. In recipient environments, M. leidyi pre-adapts for rapid colonization, due to a high metabolism and reproduction rates. It created extensive populations with the various patterns of annual cycle and distribution and heavily impacted the ecosystems.