A population of the alien jellyfish , Cassiopea andromeda ( Forsskål , 1775 ) ( Cnidaria : Scyphozoa : Rhizostomea ) in the Ölüdeniz Lagoon , Turkey

An established population of the alien jellyfish Cassiopea andromeda is present in Ölüdeniz Lagoon, off southwestern Turkey. This is the third record of this invasive species off the Turkish coast. The high abundance of the species in the Ölüdeniz Lagoon and along the Turkish coast is of great concern as it may annoy bathers and impact tourism.

Cassiopea andromeda (Forsskål, 1775) entered the Mediterranean Sea via the Suez Canal (Galil et al. 1990). The first Turkish record consisted of a single specimen, from Sarsala Bay, Fethiye, Göcek (Bilecenoğlu 2002). Subsequently, six specimens were reported from the Bay of İskenderun (Çevik et al. 2006). We report the presence of an established population in Ölüdeniz Lagoon.
Ölüdeniz Lagoon is located 14 km south of the Fethiye, on the southwestern coast of Turkey ( Figure 1). The lagoon is approximately 1300 m long and 650 m wide, with maximum depth of 39 m. Its mouth is 7 m wide and 5 m deep. The surface water temperature in August, 2003 was 29.9°C, andin March, 2004, 17.2°C. Salinity was highest (38.8 PSU) near the inlet and lowest (34.5 PSU) inside the lagoon (TUDAV 2004).
Cassiopea andromeda was first observed in August, 2000, in the north shallow end of the Lagoon (station 4b, Figure 2). In 2003 and 2004 large numbers were observed in several locations in the lagoon. However, Öztürk et al. (2005), who studied the biodiversity of the lagoon misidentified it as Cotylorhiza tuberculata (Macri, 1778). Öztürk et al. (2005) (Forskal, 1775). The mode of introduction C. andromeda is unclear. The juvenile benthic stage may have arrived in ships' hull-fouling; the pelagic stage in ballast water, or ephyrae may have reached the area with water currents from the Levantine coast (Çevik et al. 2006). Ölüdeniz Lagoon is located 15 nautical miles from the port of Fethiye.
Between August, 2003 andMay, 2004, the presence and mean abundance of C. andromeda was studied in six stations, representing different habitat types in the lagoon (Figure 2). The abundance was calculated by line transect method; counting the individuals in a 100 m 2 (5m-wide by 20m-long) rectangular plot. Large numbers of C. andromeda were observed in the stations 1a, 1b, 2, 4a, 4b, 5 and 6 (Annex 1). Stations 1a,b consist of a steep rocky shore to depth of 6m and a deeper muddy silty bottom. Station 2 consists of a shallow, marshy area with Zostera marina beds at the depths of 4-10 m. Station 3 has a rocky coastline and muddy bottom at a depth of 6 m. Stations 4a and 4b are shallow and marshy. Between these two stations is a touristic sandy beach. Station 5 has a dense   marshy coast with extended silty, muddy bottoms and waters shallower than 4m. Station 6 is a touristic sandy beach.
Ölüdeniz Lagoon was declared a Specially Protected Area (SPA) by the Turkish Ministry of Environment in 1988. It is also a popular tourist destination, visited by 500.000 persons each summer. Like other jellyfish, Cassiopea is armed with nematocysts which stings may cause welts, rashes, itching, vomiting and skeletal pains depending on the person's sensitivity to the nematocyst toxin (Eldredge and Smith 2001). The high abundance of the species in the Ölüdeniz Lagoon and along the Turkish coast is of great concern as it may annoy bathers and impact tourism. We call for further studies to map the distribution of the species along the coast and examine its possible ecological impact on native species.