Do we face a more gelatinous future under global change? Impact of the newly invaded ctenophore Mnemiopsis leidyi in northern Europe


***Monday August 13, 2012
Redfield Auditorium - 12:00 Noon
Dr. Cornelia Jaspers
Research Assistant
DTU Aqua, National Institute of Aquatic Resources
Section for Ocean Ecology and Climate
Technical University of Denmark

In recent years evidence has accumulated that gelatinous zooplankton, especially jellyfish and ctenophores are favoured under future global change scenarios. This includes increased globalization with the risk of species translocations. An example is the recent invasion by the ctenophore Mnemiopsis leidyi in northern European waters which has lead to concerns for fisheries interests especially in the central Baltic Sea, where the ctenophore overlaps with commercially important cod recruits on their spawning grounds. We present laboratory feeding rate experiments along with video recordings, in situ reproduction rates and distribution data to investigate the direct and potential indirect effect on the Baltic cod population. We show that M. leidyi constitutes neither a direct nor an indirect threat to the cod population in the central Baltic. However, due to its large reproduction potential (up to 11,500 eggs ind-1 d-1) in areas with higher salinities and observed high abundances in parts of northern Europe, M. leidyi must still be regarded as a severe potential food competitor with fish in these systems.