Allochthonous and vagrant ichthyofauna in Hellenic marine and estuarine waters

A review of the non-indigenous ichthyofauna occurring in the Hellenic marine and estuarine waters is presented, including Atlantic origin colonizers, aquaculture introduced and Lessepsian alien species. 34 non-native species have been registered. The majority of allochthonous fish are Lessepsian immigrants, which represent approximately 80% of the ascertained non-native ichthyofauna in Hellenic waters; their establishment, spread, habitat, abundance and interaction with indigenous fish are discussed

On the finding of the Indo-Pacific fish Scomberomorus commerson in Rhodes (Greece)

The occurrence of the Indo-Pacific fish Scomberomorus commerson was observed for the first time in the Hellenic waters of the SE Aegean Sea during the spring 2008. The record may represent a first indication of a population expansion of this alien species along the southern coasts of the Aegean Sea

First occurrence of Actaeodes tomentosus (H. Milne Edwards, 1834) (Brachyura: Xanthidae: Actaeinae) in the Mediterranean Sea

The presence of the crab Actaeodes tomentosus, native to the Indo-Pacific Ocean and the Red Sea, is documented for the first time in the Mediterranean Sea, on the basis of two specimens collected from Rhodes Island (Aegean Sea), a marine area particularly vulnerable to warm-water alien invasions. Along with the recent report of Xanthias lamarckii in similar conditions and region, the finding of another non-indigenous xanthid opens many questions regarding their occurrence in the area. Apart from the Lessepsian migration, other possible vectors of introduction are therefore examined

Description of the first Lessepsian squid migrant, Sepioteuthis lessoniana (CEPHALOPODA: Loliginidae), in the Aegean Sea (Eastern Mediterranean)

Loliginid squids of the Sepioteuthis lessoniana complex are widely spread in the Indo-Pacific Ocean, where they constitute a commercially important resource for neritic fisheries. Sepioteuthis lessoniana is the only Lessepsian squid migrant till now, recorded for the first time in the Mediterranean in 2002 along the Turkish Levantine coasts. Two maturing males, with mantle lengths 193 mm and 244 mm, have been recently caught near the coasts of Rhodes Island (SE Aegean), extending the species distribution northward, into Hellenic waters. Their identity was confirmed by comparison of the main body, beak characteristics and morphometric measurements with those available in the literature for this species. Suspected expansion of the Lessepsian loliginid into the Aegean Sea, due to the gradual warming of the sea, is discussed

Occurrence of the lessepsian species Portunus pelagicus (Crustacea) and Apogon pharaonis (Pisces) in the marine area of Rhodes Island

A large number of Red Sea species are colonizing the eastern Mediterranean Sea via the Suez Canal, mainly following the Anatolian coasts and spreading westwards. Portunus pelagicus is one of the most common Red Sea swimming crabs, first recorded in the Levantine Basin in 1898. Four specimens of P. pelagicus were collected in different marine areas of Rhodes Island from 1991 to 2000, while three specimens of the lessepsian fish Apogon pharaonis, first recorded in the Mediterranean in 1947, were caught during 2002 in the NW coast of Rhodes. The sub-tropical character of the marine area around Rhodes seems to facilitate the propagation of lessepsian species. These migrants have reached the island at different velocity and degree of establishment of their populations. The occurrence of the blue swimmer crab P. pelagicus and of the bullseye cardinal fish A. pharaonis increases the number of the decapod Crustacea and fish species of Red Sea origin observed in Greek waters

Macrophthalmus graeffei A. Milne Edwards, 1873 (Crustacea: Brachyura: Macrophthalmidae): a new Indo-Pacific guest off Rhodes Island (SE Aegean Sea, Greece)

A new alien crab, the macrophthalmid Macrophthalmus graeffei, is reported from the eastern coastline of Rhodes Island. The species, of Indo-West Pacific origin, is known from muddy sediments up to about 80 m depth. In the Mediterranean, its presence has been observed along Levantine coasts as well as along the Turkish coast of the Aegean Sea.Macrophthalmus graeffei increases to twelve the number of alien brachyurans present in the Hellenic SE Aegean Sea, ten of them having Indo-Pacific origin

A new alien crab for the Mediterranean Sea: Xanthias lamarckii (H. Milne Edwards, 1834) (Crustacea: Decapoda: Brachyura: Xanthidae)

A single specimen of Xanthias lamarckii was collected on March 2013 from the shallow waters of Chtenia, a rocky islet near Rhodes Island, south-eastern Aegean Sea. The occurrence of this Indo-West Pacific species is reported for the first time in the Mediterranean waters and documents the ongoing process of biological invasion of the basin. The vector of introduction of X. lamarckii is unknown so far, waiting for future information on establishment and spread of the species in its new environment

Update of marine alien species in Hellenic waters

The list of marine alien species in Hellenic waters is updated taking into account new findings (published and unpublished data). According to the present work, the number of these species has increased from 90 (known until end 2003) to 128. Most of them are zoobenthic species followed by fish and macroalgae. An interannual analysis revealed an important increase of alien species during the last years. The study of their geographic distribution showed that their majority is present in the southeastern Aegean. More than 55% of them are well established, while about 40% are casual records. Their main pathway of introduction seems to be the Suez Canal followed by shipping, whereas the Straits of Gibraltar, aquaculture and the Straits of Dardanelles appear to play a less important role in their invasion of Hellenic waters. These findings are discussed considering environmental and anthropogenic factors

Gonioinfradens paucidentatus (A. Milne Edwards, 1861) (Crustacea, Decapoda, Portunidae): a new alien crab in the Mediterranean Sea

The first record for the Mediterranean Sea of the Red Sea/Indo-Pacific portunid Gonioinfradens paucidentatus (red swimming crab) is documented. A detailed description of the specimens collected at Rodos Island (southeastern Aegean Sea) is given, while possible introduction vectors of the species in the area are discussed

Thirty years after - dramatic change in the coastal marine habitats of Kos Island (Greece), 1981-2013.

Results of recent fieldwork were compared with data collected in 1981, taken as a reference condition. Surveys were conducted with the same method (time-based visual census along random paths), in the same sites, by the same people. Semi-quantitative inventories of conspicuous species were analysed by univariate and multivariate techniques. Available information on the main potential stressors indicated that a regime shift has occurred in these 30+ years: sea surface temperature rose by1-2°C, human pressure grew impressively, and invasion by several alien species took place. Consistently, a phase shift occurred in the biological communities. Of the 120 conspicuous species found in total, only 51 were common to both surveys; 31 species ('losses') were found in 1981 but not again in 2013, 38 ('gains') were found exclusively in 2013, 16 ('winners') increased their abundance, 8 ('losers') got scarcer, and 27 underwent little or no change. Gains included 7 alien, 2 nitrophilic, and 7 thermophilic species. Multivariate analysis evidenced biotic homogenisation in 2013 and huge change in rocky reef habitats. The once flourishing algal forests have disappeared to leave space to sponges and wide areas of bare substratum. This has most probably been the result of overgrazing by alien herbivorous fishes (Siganus luridus and S. rivulatus), whose establishment and spread has been favoured by seawater warming; the synergic action of local human impacts was also evidenced