Invading the Greek Seas: Spatiotemporal Patterns of Marine Impactful Alien and Cryptogenic Species

The Greek Seas are greatly exposed to the proliferation of marine alien species. At least 242 species have been reported within territorial waters, three-quarters which considered established, while their rate introduction is increasing. Some these exhibit high invasiveness, imposing severe impacts on native ecosystems and ecosystem services. spatiotemporal outside natural boundaries depends several parameters, including biological characteristics, distribution range, pathway, time initial introduction. Knowing current potential essential for implementation effective management actions. To investigate impactful cryptogenic (ICAS) in Seas, we combined all records available until end 2020 from eight types data sources: (1) scientific literature, (2) grey (3) offline databases, (4) online (5) personal observations independent researchers, (6) communications with divers diving centers, (7) situ underwater sampling, (8) social networks. results 5478 georeferenced refer 60 ICAS belonging 16 taxonomic groups. number overall present an increasing trend northern southern parts our study area, there a clear distinction community composition between subregions. This latitudinal gradient mainly due large thermophilous Lessepsian West Indo-Pacific origin, reach area through unaided dispersal. On other hand, transport stowaways appear be more prevalent areas located near ports, show significant differences numbers compared sites far ports. Most (>40% total) were associated rocky reefs, partly reflecting preference this habitat type but also presence conspicuous, reef-associated fish. published records, as well ICAS, shows dramatic increase time, highlighting urgent need immediate proactive actions scientifically informed control measures.