Abstract: The invasive species comb jelly Mnemiopsis leidyi was introduced into the Caspian via the ballast water into the Caspian Sea in 1998. Distribution, biomass and abundance studies of the comb jelly M. leidyi were conducted in the southeast region of the Caspian Sea (Mazandaran-Goharbaran) in 8 stations with deep Profile stations of 5, 10 and 15 m in 2013. M. leidyi was collected with a METU net having a mouth opening of 0.2 m2 and mesh size of 500 µm. M. leidyi was observed at all stations all over the sampling periods during January to December 2013. There was a seasonal pattern of ctenophore density, the maximum being observed in autumn (August and September), and the minimum in the winter months. The highest abundance and biomass (wet weight) of M. leidyi were recorded with 71.8 ± 8.2ind.m-3 and 1.9 ± 1.0g.m-3, while the minimum were in winter with 14.4 ± 2.0ind.m-3 and 0.3 ± 0.01g.m-3. The highest monthly mean M. leidyi abundance and biomass were 128.3 ± 25.2 ind.m-3 in September and 3.1 ± 1.2g.m-3 in August. During the whole study period and at all stations, small individuals (<5 mm in length) and the Cydipid stage constituted 90.4% of all individuals, whereas 6.3% of the individuals were 6–10 mm in size.Abstract: The invasive species comb jelly Mnemiopsis leidyi was introduced into the Caspian via the ballast water into the Caspian Sea in 1998. Distribution, biomass and abundance studies of the comb jelly M. leidyi were conducted in the southeast region of the Caspian Sea (Mazandaran-Goharbaran) in 8 stations with deep Profile stations of 5, 10 and 15 m in ...Show More
