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

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

Torquigener flavimaculosus Hardy and Randall, 1983 (Pisces: Tetraodontidae) off Rhodes island marine area: a new alien fish in the Hellenic waters

The presence of the pufferfish Torquigener flavimaculosus was recorded during the winter 2006-2007 off Rhodes Island (SE Aegean Sea). The species, known from the western Indian Ocean, has established populations from the Levantine basin to Fethiye, Turkey. This finding expands the known range of the species in the Mediterranean to the south-eastern Aegean Sea

Tetraodontid colonizers in the Aegean Sea; Second record of the spiny blaasop,Tylerius spinosissimus(Actinopterygii: Tetraodontiformes: Tetraodontidae)

A second record of the small Indo-Pacific fish Tylerius spinosissimus (Tetraodontidae) (known as spiny blaasop) was documented at the beginning of 2009 in the waters of Rhodes Island (south-eastern Aegean Sea, Greece). The finding shows the putative establishment of a population of this alien fish in the Mediterranean with a centre the Dodecanese plateau

Alien Fish Species in the Eastern Mediterranean Sea: Invasion Biology in Coastal Ecosystems

The spread of non-indigenous species (NIS) in the eastern Mediterranean Sea is an ongoing and accelerating process. Non-indigenous species are regularly reported from various coastal habitats in the eastern Mediterranean Sea but fundamental knowledge on the assemblage structure of coastal fish communities are lacking. This thesis aims to increase the knowledge on the fish assemblage structure and function of Posidonia oceanica meadows and sandy habitats in a coastal area of the eastern Mediterranean Sea and give insight into invasion biology by investigating the potential impact of introduced fish species to the local ecology and food-web of the marine systems under study. Functional and feeding guilds were developed to investigate the fish assemblage structure and function of coastal fish communities and to assess the potential role of NIS in the food web. In addition, diet nvestigations were considered important first steps in order to evaluate the potential role and impact of recently established NIS in the recipient region. During the sampling campaign two species were for the first time reported in the area. Posidonia oceanica was found to be a multifunctional habitat for fish species. It was found to be a highly important nursery habitat for several species during summer and a habitat that could under certain seasons concurrently be used by both adults and juveniles. Four functional guilds were created to describe the habitat use of P. oceanica meadows for each species encountered; juvenile migrants, seagrass residents, seasonal migrants and occasional visitors. Affinity of each species to P. oceanica was assessed in a comparison with each species distribution on open sand within the same depth range. Among the 88 species encountered, eleven were found to be non- indigenous of Indo-Pacific and Red Sea origin, three of them using segrass mainly as juveniles, and four as residents. In a comparison of fish assemblage structure between seagrass and sandy habitats quantitative sampling in combination with classification of fish species into six major feeding guilds revealed the position and contribution of non-indigenous species (NIS) in the food web of Posidonia oceanica and sandy habitats. In P. oceanica beds and on sandy bottoms 10 and five species, respectively, were non-indigenous of Indo-Pacific and Red Sea origin. The proportional contribution of NIS individuals on P. oceanica beds was lower than that of sandy bottoms (12.7 vs. 20.4 %) a pattern that also followed for biomass (13.6 vs. 23.4 %), indicating that low diverse systems may be more prone to introductions than species-rich communities. The two habitats had similar fish feeding guilds, but the biomass contribution from NIS varied within each guild, indicating different degrees of impact on the available resources. Size was considered highly important due to habitat shift of species with increased size. Two of the aspects considered in this study, the chance of establishing and the chance of being very dominant will depend upon competitive abilities strongly coupled to size and grounds for habitat shift. However, success of establishment will also depend on appropriate food resources in the recipient community as well as competitive abilities and level of competition in the food web within habitats. No support could be found for the theory that taxonomic affiliation could facilitate invasion success. The non-indigenous bluespotted cornetfish Fistularia commersonii was found to be a strictly piscivore predator and the diet consisted of 96 % by number and >99 % by weight of fish. The diet of F. commersonii was related to time of year, and fish size. Size classification and habitat of prey groups (benthic, supra-benthic, and pelagic) showed that with increased body length it extended its diet to larger prey and more generalist feeding. Fistularia commersonii was found to prey on commercial important native species (e.g. Spicara smaris, Boops boops, Mullus surmuletus) and the absence of NIS from its diet was mainly attributed to the absence of NIS with elongated body shape. The feeding ecology of two common indigenous (Sphyraena sphyraena and Sphyraena viridensis) and one abundant non-indigenous barracuda, Sphyraena chrysotaenia, of Indo-Pacific origin, was investigated. Confamilial feeding interactions was studied to investigate overlap in feeding preferences in relation to availability of prey items. Dietary analyses revealed that all three species examined were specialized piscivores with their diet consisting to more than 90 % of fish, both by number and weight. All three predators examined showed a significant selectivity towards Atherina hepsetus. Diet breadth and size of prey increased with increased body size, whereas diet overlap between indigenous and NIS decreased, attributed to increased diet breadth and specific life characteristics of indigenous species developing into larger predators extending their foraging habits. During winter, condition of the NIS was significantly lower than that of the indigenous species, indicating that winter temperature in the studied area may be a limiting factor for further population growth of this Indo-Pacific species. This study filled the gap in knowledge about the feeding preferences of the most abundant piscivorous species found on the coasts of the studied area. Additionally, congeneric affiliation of fish introductions was not found to be an important factor explaining successful establishment of NIS. The non-indigenous toxic pufferfish, Lagocephalus sceleratus, was reported for the first time in the Mediterranean in 2003 and two years later in the coastal habitats of Rhodes. The ecological and societal impact of the pest pufferfish was investigated in coastal habitats of Rhodes. Seasonal quantitative sampling in two common coastal habitats was used to investigate habitat use of different life-stages. Sandy areas were found to be highly important for the early life stages of L. sceleratus. In contrast, Posidonia oceanica habitats were mainly preferred by larger (> 29 cm) reproductive adults with a maximum recorded size of 64 cm. Lagocephalus sceleratus was fond to be an invertebrate and fish feeder while size classification revealed a tendency for an ontogenetic diet shift with increased size to a molluscivore feeding. The ontogenetic diet shift is most probably attributed to a shift in habitat use with increasing size. During early life stages L. sceleratus inhabited sandy bottoms where it fed on various invertebrates, including the genus Nassarius and Dentaliidae. The predominant molluscan species found in the diet of larger (> 20 cm) L. sceleratus individuals was Sepia officinalis while predation of Octopus vulgaris was less successful. Sepia officinalis and O. vulgaris are of economic interest in the area and the impact of L. sceleratus on local stocks of these species is discussed. Societal impacts were also evident in the area due to increased public attention concerning the lethal effects of the toxic L. sceleratus, if consumed. Seasonal variations in the condition of L. sceleratus did not show any significance and the high conditional values together with information on high numbers caught during samplings, signifies its ability to become an important member of the coastal fish community. Combined ecological, economical and social effects clearly classify L. sceleratus a pest in the area