Mediterranean non indigenous species at the start of the 2020s: recent changes

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, backdated 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 subtropical 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.

Numerous new records of tropical non-indigenous species in the Eastern Mediterranean highlight the challenges of their recognition and identification

“…The Eastern Mediterranean Sea is a hotspot of non-indigenous species introductions. The opening of the Suez Canal in 1869 broke a long-standing biogeographic barrier and enabled hundreds of Red Sea species to enter the basin and establish populations ( Por 1978 ; Galil 2009 ; Zenetos et al 2010 , 2017 ; Zenetos and Galanidi 2020 ). These so-called Lessepsian species are now recorded from all countries bordering this basin west to Greece ( Katsanevakis et al 2009 ; Çinar et al 2011 ; Ammar 2018 ; Zenetos et al 2018 ; Bariche and Fricke 2020 ; Crocetta et al 2020 ) and some have already reached the central Mediterranean, e.g., Tunisia (Ounifi-Ben Amor et al 2015), Italy ( Occhipinti-Ambrogi et al 2011 ), and even France ( Daniel et al 2009 ; Bodilis et al 2011 ).…”

First record of a seed shrimp (Ostracoda: Podocopida) Cypretta campechensis (Cyprididae) in a perennial lake (Coimbatore, India): Its molecular identification

“…Barcode [70,71] . The biogeographic range of Subeucalanus subtenuis, Subeucalanus mucronatus, Subeucalanus subcrassus and Pareucalanus langae have been extended in the western Indian Ocean; the Indo-Pacific region consist of genetically divergent, allopatric populations of Subeucalanus pileatus, Pareucalanus sewelli, Rhincalanus rostrifrons, Arietellus pavoninus, Codium pulvinatum and Boccardia proboscidea; genetically divergent lineages of Subeucalanus crassus and Rhincalanus nasutus have been inadequately characterized (Suatoni et al, 2006; Zenetos and Galanidi, 2020) [72,73] . The sequence divergence has also been reported in Candacia, Pareucalanus, Rhincalanus and Temora (Pitz et al, 2020) [74] .…”

Possible implications of sea level changes for species migration through the Suez Canal

“…(e.g., reduction in pool of potential non-indigenous species). In fact, there are mixed reports regarding the recent migration trends, with some indicating a general slowdown in the rate of species entry into the Mediterranean 6 , 44 , and others pointing to an increasing introduction rate of fish via the SC 45 .…”