A new alien bryozoan Celleporaria brunnea (Hincks, 1884) in the Aegean Sea (eastern Mediterranean)

Non-induced movements of marine species between different biogeographical regions are an increasing trend worldwide (Por, 1971; Leppakoski, 1991; Gollasch, 2002; Paavola et al., 2005). The Mediterranean Sea is one of the major recipients of alien species (Galil, 2000; Galil and Zenetos, 2002). The main vectors of introduction of alien species in the region are Lessepsian migration, shipping and aquaculture (Cognetti and Maltagliati, 2000). The opening of the Suez Canal in 1869 resulted in the migration of Red Sea species to the eastern Mediterranean basin (Por, 1971; Zibrowius, 1991). According to Streftaris et al. (2005), Erythrean species entering the Mediterranean using the Suez Canal constitute a significant part (52%) of the exotic fauna and flora in the Mediterranean Sea, and within this zoobenthic organisms are the most important taxa, accounting for 70% of the aliens. Particular conditions within ports, including eutrophication and pollution, may facilitate the establishment of alien species (Minchin and Gollasch, 2003; Galil, 2000). High food availability in ports may also facilitate the settlement of alien species (Koçak et al., 1993). Most invasive species have an r-selected life history and their capacity to tolerate environmental stress allows them to become SCIENTIA MARINA 71(1) March 2007, 191-195, Barcelona (Spain) ISSN: 0214-8358


INTRODUCTION
Non-induced movements of marine species between different biogeographical regions are an increasing trend worldwide (Por, 1971;Leppakoski, 1991;Gollasch, 2002;Paavola et al., 2005).The Mediterranean Sea is one of the major recipients of alien species (Galil, 2000;Galil and Zenetos, 2002).The main vectors of introduction of alien species in the region are Lessepsian migration, shipping and aquaculture (Cognetti and Maltagliati, 2000).The opening of the Suez Canal in 1869 resulted in the migration of Red Sea species to the eastern Mediterranean basin (Por, 1971;Zibrowius, 1991).
According to Streftaris et al. (2005), Erythrean species entering the Mediterranean using the Suez Canal constitute a significant part (52%) of the exotic fauna and flora in the Mediterranean Sea, and within this zoobenthic organisms are the most important taxa, accounting for 70% of the aliens.
Particular conditions within ports, including eutrophication and pollution, may facilitate the establishment of alien species (Minchin and Gollasch, 2003;Galil, 2000).High food availability in ports may also facilitate the settlement of alien species (Koçak et al., 1993).Most invasive species have an r-selected life history and their capacity to tolerate environmental stress allows them to become established easily in new non-native habitats and to be competitively dominant over native species (Byers, 2002;McMahon, 2002;Ambrogi and Savini, 2003).In brackish waters, low species richness provides less competition and unoccupied niches for establishing species (Leppakoski and Olenin, 2000;Paavola, et al., 2005).
The present study provides a new distant locality for C. brunnea, and additional information about its morphological and ecological characters.

MATERIALS AND METHODS
The present results are part of a study carried out seasonally from July 2003 to-September 2004 at four hard-bottom stations in Izmir Bay (Aegean Sea) (Fig. 1).At each station, three samples were taken at 0.2 m depth by scraping off an area of 400 cm 2 using a spatula.Material was fixed in 4% formaldehyde in the field and washed through a sieve with 0.5 mm mesh size in the laboratory.Afterwards, samples were sorted under a stereomicroscope and preserved in 70% ethanol.At all stations, bryozoan species were determined at species level.In September 2004, a new alien bryozoan species, Celleporaria brunnea, was found on Mytilus galloprovincialis species at Station 4 near Çakalburnu Lagoon.Measurements of some parts of zooids were made using ocular micrometer.The autozooid morphology was illustrated by scanning electron microscope (SEM).The specimens are deposited at the Museum of the Faculty of Fisheries, Ege University (ESFM: Ege Üniversitesi Su Ürünleri Fakültesi Müzesi).
Distribution.Celleporaria brunnea is one of the most common species in California and Baja California waters (Soule and Soule, 1964).The distribution of the species extends from British Colombia southward to Ecuador (Soule et al., 1997).This species was found in the vicinity of the Panama Canal (Hastings, 1929).It was also recorded from Hawaii, where it may have been transported via hull fouling (Godwin, 2003).
The genus Celleporaria includes 72 recent species worldwide.Among them, three species have been previously reported from the Mediterranean Sea: Celleporaria aperta (Hincks, 1882), Celleporaria fusca (Busk, 1854) and Celleporaria pilaefera (Canu and Bassler, 1929).Celleporaria aperta was first found on the Israeli coast and considered as a Lessepsian migrant (Powell, 1969a).Agius et al. (1977) reported this species and C. pilaefera on the fouling cages of an oyster farm on Malta Island and suggested that they were introduced there via shipping.A total of 6 Celleporaria species [C. labelligera Harmer, 1957, C. vermiformis (Waters, 1909), C. columnaris (Busk, 1881), C. trispiculata d 'Hondt, 1988, C. bicornis (Canu and Bassler, 1923) and C. pigmentaria (Waters, 1909)] were reported from the Red Sea (Powell, 1969a;1969b;d'Hondt, 1988).The species belonging to this genus show a strong positive response to free space and are highly opportunistic and invasive (Dunstan and Johnson, 2004).Thus, they have favourable attributes to colonise new habitats.Celleporaria brunnea, which was known to inhabit tropical and temperate (warm and cool temperate) waters (Soule and Soule, 1964), was recorded for the first time in the Mediterranean Basin.
In the genus Celleporaria, the main morphological characters used in systematics are the shape of aperture, size, and the position and type of avicularia.In the Aegean specimens of C. brunnea, dark brown operculum and sclerites of mandibles in both oral and interzooidal avicularia were noted.In these specimens, the aperture was rounded distally but a distinct notch was not observed in the proximal part, as described by Soule (1961), Soule and Soule (1964) and Soule et al. (1997).The proximal border of apertures of our specimens was concave and arcshaped, with lateral condyles.The mandible of large interzooidal avicularia on the Pacific specimens had a spade-shaped brown reinforced sclerite in the midline (Soule and Soule, 1964).However, the mandible of interzooidal avicularia of our specimens had a spade-like sclerite with a short handle, as observed on the specimens collected from the coasts of Ecuador and Galapagos (Osburn, 1952;Hastings, 1929).ACKNOWLEDGMENTS I am much indebted to Jean-Georges Harmelin (France) for his constructive comments on the manuscript and for the photos taken by him with SEM.The study was carried out within the framework of the project "Seasonal dynamics of zoobenthos distributed in and around Alsancak Harbor (Izmir Bay, Turkey) and impacts of probable exotic species introduced by ships on the ecosystem-Project no.03 SÜF 005".SCI. MAR., 71(1), March 2007, 191-195 FIG. 1. -Map of the investigated area with the location of stations.Celleporaria brunnea was collected only at Station 4.