摘要:The comb jelly Mnemiopsis leidyi was first reported in July 2009 along the Spanish coast of the NW Mediterranean Sea and occurred throughout the summer (last report 26 September 2009). Large numbers of the ctenophore were reported by many participants of the “Medusa Project”. The high concentrations of M. leidyi along the Spanish coast, together with its blooms earlier this year in Israel, suggests establishment in the Mediterranean Sea. This is of great concern because of the well-known effects of M. leidyi on marine ecosystems and the consequences for commercial fisheries.