Invasive comb jellyfish (M leidyi)
The American comb jellyfish (Mnemiopsis leidyi) invaded
the Black and Caspian Seas in large numbers in the 1980s. Its
presence and distribution led to major changes in the marine
ecosystem and resulted in economic losses, due to a decline in fish
and shellfish stocks.
In 2006 this species was detected in several locations in the
southern North Sea, supposedly transferred from the North American
east coast through ships' ballast water.
The potential spread of M. Leidyi in the "2-Seas area"
(the southern North Sea and the Channel) is a major concern because
of the presence of important spawning and nursery grounds and
migration routes for many commercial fish and shellfish
The impact of the interaction of M. Leidyi with
potential prey and predators must be closely monitored to avoid
repetition of the events seen in the 1980s.
The MEMO project
This project - the acronym of which stands for
"Mnemiopsis Ecology, Modelling and Observation" - aims to
study this invasive comb jelly in the southern North Sea and the
It is being funded by the EU's Interreg Iva - 2-Seas programme.
A budget of €3.5 million has been allocated to five scientific
The ultimate goal is to raise awareness about the potential risk
of M. leidyi on marine ecosystems and professional
activities in the 2-Seas region, and to identify possible measures
to counter this threat.
The project is split into three activities:
- Development of standard procedures for the identification,
monitoring and modelling of potential habitats and population
dynamics of M. leidyi (ILVO to lead)
- Study of the physiology, feeding behavior and potential prey
and predators of the species through experiments and mathematical
models (IFREMER to lead)
- Evaluation of the potential environmental and socio-economic
costs of the impact of this species using an ecosystem-based
approach (Cefas to lead).
During the three years of the project, which began on 1 January
2011, the partners also hope to improve and standardise monitoring
capabilities among themselves. Through their cross-border
co-operation, they will exchange expertise and knowledge on
taxonomy, databases, data analysis and modelling techniques.
For more about the MEMO project visit www.ilvo.vlaanderen.be/memo.
- American comb jellyfish (Mnemiopsis
leidyi, whose taxonomic phylum is ctenophore) measures up to
12cm, although in the 2-Seas area it has been observed to be around
- It is a voracious animal that feeds on fish eggs, larvae and
plankton. It appears to need little energy.
- It is a hermaphrodite with a reproductive cycle of about two
- It has been found to survive in the North Sea during cold
For more information about this species visit: