Changes in distribution and lengths of Mnemiopsis leidyi in the central Baltic Sea between fall and spring

In March 2008, we conducted a survey to investigate the distribution and abundance of the invasive ctenophore Mnemiopsis leidyi in the Bornholm Basin after the winter period. Compared to the situation in November 2007 the centre of the distribution had shifted towards the deeper parts of the Basin where temperatures were higher than at the surface. Furthermore, we found a decrease in average size from 18.6 mm ± 7.6 SD in November to an average of 10.5 mm ± 4.9 SD in March, which may indicate the emergence of a new generation of M. leidyi between the two sampling dates.