Parasites and bacteria isolated from ctenophore invaders, Mnemiopsis leidyi and Beroe ovata

Mnemiopsis leidyi (comb jelly) is an exotic species which has not been reported from the caspian sea till 1999, but it was observed and reported from the southern coasts of caspian sea in 1999 (esmaili sari, 1999). invasion of the mnemiopsis leidyi to the caspian sea pelagic ecosystem has been one of the main difficulties in the past decade (parafkandeh haghighi and kaymaram, 2011). mnemiopsis leidyi has been brought from the black sea to the caspian sea by ballast water of ships and it has settled in the southern caspian sea through the time.there is a little information regarding the microbial flora in comb jelly (estes et al., 1997) but a large number of comb jelly carry natural flora and pathogens located in the coastal waters such as aeromonas and vibrio. however, it might have been entered into the caspian sea many years ago, but it has recently caused execessive reduction in kilka fish stocks because it is considered as a food competitors for them. the comb jelly may also carry some new microrganisms like parasites and microbial flora to the caspian sea. this study was carried out to investigate the parasites and bacterial flora of b. ovata and m. leidyi as probable dangers for the caspian sea ecosystem.