Meeting Abstract

P2.48  Tuesday, Jan. 5  Diel vertical distribution assessment of the invasive ctenophore, Mnemiopsis leidyi, off Anzali Coast, South Caspian Sea, Iran SEYFABADI, Jafar*; HEYDARI, Masoud; Tarbiat Modares University jseyfabadi@gmail.com

The diel vertical distribution and abundance of the invasive comb jelly, Mnemiopsis leidyi , in the south Caspian Sea were studied during three diel periods in August 16-17, 27-28 and 29-30, 2007, at one station (depth ~ 50m) off Anzali coast, Iran. The determinative factor in general zooplanktonic abundance was found to be the thermocline with its base being located at around 20– 35 m depths during the sampling period. As a result, the zooplankton abundance decreased from surface to depth, being higher in waters above the thermocline, especially 0-10 m layer. Although the presence of M. leidyi in all depths was evident, higher abundance and distribution were always encountered in the surface waters above the thermocline (depth 20 m) both days and nights, indicating no occurrence of diel vertical migration. Therefore, temperature and food availability could be considered as the main factors in the vertical distribution of M. leidyi.