COMPARATIVE STUDY ON LIPID QUALITY OF DISTRIBUTION AND ABUNDANCE OF MN EM IOPSIS LEIDYI THE EASTERN IRANIAN COASTS OF THE CASPIAN SEA

The alien ctenophore Mnemiopsis leidyi which was transported from the Black Sea into the Caspian Sea at the end of 1990s has been negatively affecting ecosystem in this new environment. In this study, spatial and temporal distribution of M.leidyi were studied from a total of stations located along three transects (Amirabad, Babolsar and Nowshar) in the Eeastern Iranian coasts of the Caspian Sea (Mazandaran province) during July 2001 to November 2002.
M. leidyi acheived maximum biomass 1024.5 g/m2 in August-October 2002. Minimum biomass (1.5 g/m2 of ctenophore were measured in December-Jaunuary 2001. The highest biomass was at the stations with 10m bottom depth (570.7 g/m2 in autumn and lowest biomass (75.9 g/m2) was obtained at a station with a 50 m bottom depth in winter. The highest average biomass (641.2 g/m2) were measured in ~irabad region and the lowest biomass (207.5 g/m2) observed in Nowshar region.
The young specimens (<5 mm) contributed about 90% to the total abundance of the population. The maximum length was 51-55mm which was measured in August. The factors affecting the distribution of M. leidyi in the study area were discussed.