State of Mnemiopsis leidyi (Ctenophora: Lobata) and mesozooplankton in Iranian waters of the Caspian Sea during 2008 in comparison with previous surveys

Abstract

Mnemiopsis leidyi which was accidentally introduced into the Caspian Sea in 1999 and since then has colonized extensively. The horizontal distribution of M. leidyi and dominant mesozooplankton species was investigated in the south western Caspian Sea during February, May, July and November 2008. The average number and biomass of M. leidyi were in the same range (ca 200 individuals.m-3 (2000 ind.m-2) and 16 g wet weight.m-3 (180 g.m-2) in comparison with previous surveys. As in previous years the population consisted mainly of individuals