SHORT COMMUNICATION Preservation of the invasive ctenophore Mnemiopsis leidyi using acidic Lugol’s

During baseline studies of ichthyoplankton for environmental impact assessment in the Western Baltic Sea, we developed a simple method for preservation of the abundant ctenophore, Mnemiopsis leidyi, using acidic Lugol’s solution. The ctenophore, Mnemiopsis leidyi, is a widely distributed species in North American and European coastal waters. The species is a significant planktonic predator feeding on prey such as copepods, fish eggs and fish larvae. Mnemiopsis leidyi are self-fertilizing hermaphro-dites with each individual producing several thousand offspring and blooms of this ctenophore occur at regular intervals (Purcell et al., 2001). In such situations M. leidyi may seriously influence zooplankton commu-nities and cause long-lasting perturbations of the ecosys-tem; the most prominent example is perhaps the recent rapid changes that took place after its introduction int