Investigation of Mnemiopsis leidyi feeding from the Caspian Sea zooplanktons

Mnemiopsis leidyi was sampled from December 2003 to March 2005 in 11 stations located along four regions Anzali, Khazarabad, Tourkman and Gorgan Bay using METU net in the Iranian coasts of the Caspian Sea. Study of stomach contents of M. leidyi showed that Acartia sp. belonging to Copepoda and Lamellibranchia sp. had the highest frequency comprising 66% and 13% of food items taken by the organism respectively and the least food items taken were Balanus nauplii, Rotatoria, Tintinnopsis and Podon polyphemoides. The maximum mean abundance of food item was Acartia sp. which was shown to be present in stomach content of M. leidyi caught in different depths, seasons and regions in the Iranian coasts of the Caspian Sea. For the M. leidyi larvae, the highest amount of food item was Acartia sp. and Lamellibranchia sp. with an average of 44% and 32% and the maximum abundance of food item for juvenile and mature M. leidyi was also Acartia sp. with an average of 67.5% and 66%. The results showed that the main food item for M. leidyi is Acartia sp. of the Copepoda. Hence, M. leidyi feeding has an important effect in declining zooplankton populations