Abstract
The current amendments to the Mediterranean marine Non-Indigenous Species (NIS) inventory for the period 2017-2019 are the result of a continuous literature search and update of the Hellenic Centre for Marine Research (HCMR) offline database. They take into account recent findings, previously missed records, back-dated records based on the re-examination of existing material or phylogenetic studies and changes in nomenclature. During the period 2017-2019, 70 new species were added to the inventory of established species, 25 that had escaped our attention in the past and 23 newly introduced, which have already established self-sustaining populations. Meanwhile, 22 species previously known only with casual records have established viable populations and a total of 36 species have expanded their distribution into new Marine Strategy Framework Directive regions, primarily the Central Mediterranean and the Adriatic Sea. Intensified research efforts, prompted by the reporting obligations created by recent legislation, complemented by ever expanding networks and initiatives involving citizen scientists have certainly contributed to higher rates of discovery of alien species presences. However, the expansion of tropical and sub-tropical species into the cooler waters of the Aegean, the Adriatic and the western Mediterranean indicates that the warming of Mediterranean waters due to climate change is also facilitating the geographic expansion of NIS in the region. The rate of new introductions in this 3-year period is 8 species per year for the whole Mediterranean, without taking into account casual records or species with reporting lags. Only 4 species per year enter through the Suez Canal, while a considerable number of species are introduced through shipping vectors and the aquarium trade. Acknowledging the dynamic nature of invasions and the uncertainty inherent in compiling check lists, we consider the present work as the most accurate and up-to-date NIS list to inform policy, management and decision-making.
Highlights
Alien species inventories constitute a fundamental first step and a very important tool for the implementation of relevant policies and the delineation of management approaches (Vanderhoeven et al 2017)
As management efforts/policy initiatives to tackle alien and invasive species are intensified at the global and regional level (CBD (Convention on Biological Diversity) 2011; IMAP 2017), it is imperative that such inventories are regularly updated and remain current, especially since the introduction rate of new alien species globally does not appear to level off (Seebens et al 2017 but see Zenetos 2019 for the Mediterranean), while their spread into new areas is facilitated by increasing volumes of trade and global transport networks (Latombe et al 2017; Seebens et al 2015)
The financial investments for alien species research and management have increased significantly in Europe since the early 1990s (Scalera 2010) and national monitoring schemes that cover Non-Indigenous Species (NIS) are in place in many Member States (ICES 2019)
Summary
Alien species inventories constitute a fundamental first step and a very important tool for the implementation of relevant policies and the delineation of management approaches (Vanderhoeven et al 2017).
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