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Irákleion, Greece

Katsanevakis S.,Hellenic Center for Marine Research | Issaris Y.,Hellenic Center for Marine Research | Issaris Y.,National and Kapodistrian University of Athens | Poursanidis D.,WWF Hellas | And 2 more authors.
Marine Environmental Research

The relative vulnerability of various habitat types to Caulerpa racemosa var. cylindracea invasion was investigated in the National Marine Park of Zakynthos (Ionian Sea, Greece). The density of C. racemosa fronds was modelled with generalized additive models for location, scale and shape (GAMLSS), based on an information theory approach. The species was present in as much as 33% of 748 randomly placed quadrats, which documents its aggressive establishment in the area. The probability of presence of the alga within randomly placed 20 × 20 cm quadrats was 83% on 'matte morte' (zones of fibrous remnants of a former Posidonia oceanica bed), 69% on rocky bottoms, 86% along the margins of P. oceanica meadows, 10% on sandy/muddy substrates, and 6% within P. oceanica meadows. The high frond density on 'matte morte' and rocky bottoms indicates their high vulnerability. The lowest frond density was observed within P. oceanica meadows. However, on the margins of P. oceanica meadows and within gaps in fragmented meadows relative high C. racemosa densities were observed. Such gaps within meadows represent spots of high vulnerability to C. racemosa invasion. © 2010 Elsevier Ltd. Source

Katsanevakis S.,Hellenic Center for Marine Research | Zenetos A.,Hellenic Center for Marine Research | Macic V.,Institute of Marine Biology | Beqiraj S.,University of Tirana | And 3 more authors.
Aquatic Biology

An important pathway of introduction of alien marine species in the Adriatic seems to be the northward expansion of species already established in the Ionian Sea, aided by the East Adriatic Current. We modelled the occupancy of alien marine species in the upper infralittoral zone of rocky bottoms across the Ionian-Adriatic border (Albanian and Montenegrin coastlines), based on underwater visual survey data. A method that took into account imperfect detection of the target species was applied to make unbiased occupancy estimations, based on a multi-model inference approach. A total of 6 alien species were found during the survey (in decreasing order of occupancy): Caulerpa racemosa, Percnon gibbesi, Ganonema farinosum, Lophocladia lallemandii, Asparagopsis taxiformis and Pinctada radiata. There was a general pattern of declining occupancy from northern Ionian Albanian coastal waters towards the southeastern Adriatic coastline. Possible reasons for this pattern are: (1) the invasion of some species from the northern Ionian Sea is still in progress and the limit of the current distributional range falls within or near the study area; (2) the lower temperatures in the Adriatic Sea restrict the northward expansion of thermophilic alien species; and (3) the part of Albania north of the Otranto Strait is characterized by sandy/muddy coasts, large estuarine areas and substantial freshwater input, creating a barrier for expansion of sessile species. There is a pool of 77 species established in the central Mediterranean but not yet observed in the Adriatic Sea. Among these, 14 species are present in the Greek Ionian Sea and may be considered as the most probable newcomers to the Adriatic Sea in the near future. © Inter-Research 2011. Source

Katsanevakis S.,Hellenic Center for Marine Research | Poursanidis D.,WWF Hellas | Poursanidis D.,University of Aegean | Issaris Y.,Hellenic Center for Marine Research | And 5 more authors.
Mediterranean Marine Science

International agreements as well as European and national legislation prohibit exploitation and trading of a number of edible marine shelled molluscs, due to either significant declines in their populations or destructive fishing practices. However, enforcement of existing legislation in Greece is ineffective and many populations of 'protected' species continue to decline, mainly due to poaching. The extent of illegal trading of protected bivalves and gastropods in Greek seafood restaurants was investigated by interviewing owners or managers of 219 such restaurants in 92 localities. Interviews were based on questionnaires regarding the frequency of availability in the menus and the origin of twenty-one species or groups of species, among which eight are protected - illegally exploited. Forty-two percent of the surveyed restaurants were found to serve at least one of the protected - illegally exploited species. Among the illegally traded species, Lithophaga lithophaga, Pecten jacobaeus, and Pinna nobilis were served in a relatively high proportion of the surveyed restaurants (22.8%, 19.2%, and 16.4% respectively), outrunning many commercial species. In many cases these species were always or often available (11.4%, 4.6% and 5.0% respectively). There was substantial spatial variation in the proportion of restaurants that illegally served protected species with different patterns for each species; very high proportions of illegal trading were observed in some marine regions (e.g. date mussels were served in >65% of the seafood restaurants along the coastline of Evvoikos Gulf). In most cases the illegally traded species were of local origin, while there was no finding of illegally imported molluscs from other countries. The strategy for enforcement of existing legislation should be greatly improved otherwise protection of shelled molluscs will remain ineffective. Source

Nicolaidou A.,National and Kapodistrian University of Athens | Alongi G.,University of Catania | Aydogan O.,Celal Bayar University | Catra M.,University of Catania | And 27 more authors.
Mediterranean Marine Science

The present work reports on the extended distribution of nineteen species in the Mediterranean. These are: Upeneus pori (Fish:Turkey), Bursatella leachii (Mollusca, Opisthobranchia: eastern coast of Spain), Sparisoma cretense (Fish: Ionian coast of Greece), Pseudobryopsis myura (Chlorophyta:Turkey), Aplysia dactylomela (Mollusca, Opisthobranchia: Karpathos island, and Kyklades Archipelago, Greece), Asparagopsis armata and Botryocladia madagascariensis (Rhodophyta: South Peloponnesos, Greece), Oxynotus centrina (Fish: Greece), Caulerpa racemosa var. cylindracea (Chlorophyta), Stypopodium schimperi (Phaeophyta) Siganus luridus and Stephanolepis diaspros (Fish) Percnon gibbesi (Decapoda, Brachyura) (Kyklades Archipelago, Greece), Cerithium scabridum (Mollusca, Prosobranchia: Anavissos: Greece) and Cerithium renovatum (Mollusca, Prosobranchia: N. Κriti), Cassiopea andromeda (Scyphomedusa: Rhodos Island, Greece), Abra tenuis (Mollusca Bivalvia: Vouliagmeni Lake, Greece) Lagocephalus lagocephalus (Fish: Calabrian coast, Italy) and Plocamopherus ocellatus (Mollusca, Opisthobranchia: İskenderun Bay, Turkey). Source

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