Feeding behavioral pattern and electivity index of Caspian Sea ctenophore, Mnemiopsis leidyi, in laboratory condition

The aim of study was Mnemiopsis leidyi’s feeding on zooplankton in the southern Caspian Sea. For this purpose, collecting of ctenophores from surface waters of Khazarabad area were done with a plankton net (500 microns) in 2009 Experiments had done under <18, 18-22 and 22-25oC for 70 days trial in 14 aquaria based on diversity of zooplankton (4 zooplankton groups) with salinity condition of Caspian Sea. 4 species of Caspian Sea zooplankton included: Copepod (Acartia tonsa), Rotifer (Branchionus sp.), Cladocera (Podon polyphemoides) and invertebrate benthic larvae (Hypania sp. and Nereis sp.) were collected. Feeding carried out by each 8 hours interval with 7000-9000 individuals. Zooplankton diets of the comb jelly were analyzed on quantity and quality of each feeding rate in all levels of treatments. Laboratory experiments of M. leidyi feeding showed that among different diet exposed to these animals, maximum tendency and digestion were occurred in 22-25oC from Balanide (Balanus sp., 98.1%), Rotifer (95%) and Copepods (90%), respectively. Balanus supposed to be the favorite food item with 98% digestion and Rotifers were the second group after Balanide in M. leidyi diet. Copepods included juvenile, adults and nauplii consisted 34-38% of food item in M. leidyi diet in which benthic larvae was only 27%. Electivity of M. leidyi to Balanide and Copepods adults and Nauplii (A. tonsa) being considered positively while to Nereis sp. was negative.