Abstract
In autumn 2006 the first observations of the West Atlantic comb jelly Mnemiopsis leidyi in Northern Europe were reported from the North Sea, the Skagerrak and the south-western Baltic Sea. Here we report on the further spread of this invasive ctenophore from the south-western towards the central Baltic Sea up to the south eastern Gotland Basin during autumn/winter 2006 and spring 2007. The abundances were generally low (max. 4 ind. m -3 ). While M. leidyi was located in the entire water column in Kiel Bight, it was found exceptionally below the halocline in the deep stratified central Baltic basins. Data of a weekly sampling program at a near shore sampling location in Mecklenburg Bight between January and May 2007 showed that up to 80 % of the individuals were juveniles, smaller than 1 mm total body length and that M. leidyi survived the winter in the Southern Baltic Sea, even if abundances dropped down to <1 ind. m -3 in February. A first assessment of the physiological demands of this species versus the environmental conditions of the Baltic Sea showed that the successful establishment of this ctenophore is probable in the south-western and central Baltic Sea.
Highlights
The number of species introductions into the Baltic Sea has been increasing since the end of the last century, with the highest rates observed during the last 40 years (Leppäkoski et al 2002, Gollasch and Nehring 2006)
During monitoring cruises in February, March and May 2007, M. leidyi was sampled in Kiel Bight, in the Kadet Furrow, in the Bornholm Basin and in the South Eastern Gotland Basin
The West Atlantic ctenophore M. leidyi is well known for its great invasive capacity and its significant ecological impact on zooplankton communities across its native as well as invaded distribution range
Summary
The number of species introductions into the Baltic Sea has been increasing since the end of the last century, with the highest rates observed during the last 40 years (Leppäkoski et al 2002, Gollasch and Nehring 2006). This lobate ctenophore originates from Western Atlantic coastal waters and estuaries and was accidentally introduced into the Black Sea in the early 1980s, where it showed an explosive population growth (Vinogradov et al 1989) It has spread into the adjacent Sea of Azov (Vinogradov et al 1989), Sea of Marmara (Shiganova 1993), Mediterranean Sea (Kideys and Niermann 1993) and Caspian Sea (Ivanov et al 2000) within 20 years after its introduction from eastern American coast. This collapse probably resulted from multiple factors, among which overfishing, food competi-tion and predation on the early life stages of the anchovy by M. leidyi played a prominent role (Bilio and Niermann 2004)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
