An increase of jellyfish in the Northeast Atlantic
Cnidarian jellyfish form part of the gelatinous plankton that can vary in shape and size from a few millimetres to a few metres. Jellyfish that have stinging cells on their tentacles are toxic to varying degrees. When they are found in very large numbers (called blooms), jellyfish can be detrimental to the aquaculture industry by harming farmed fish, and to tourism by curtailing bathing activities.
SAHFOS have reported a recent increase in the occurrence of North Atlantic cnidarian jellyfish and shown how climate change could explain this increase. The study based on plankton samples collected by the Continuous Plankton Recorder (CPR) in the Northeast Atlantic found that blooms of jellyfish off the Northwest European shelf, now unusually persistent during winter months, were dominated by a warm-water jellyfish called Pelagia noctiluca. Outbreaks of this species correspond with a northward spread of warm water, from mid-temperate latitudes into the Northeast Atlantic, which is under the influence of climate oscillations. SAHFOS' researchers suggest that P. noctiluca may be exploiting the recent increase in sea temperatures to reproduce more rapidly and successfully survive over the winter period.
Predictions of global climate change suggest that the North Atlantic will continue to warm so we may see more frequent blooms of P. noctiluca, along with other warm water plankton species in coastal seas where food resources are more abundant. Such predictions present a worrying ecological scenario for fish survival as jellyfish are important predators of juvenile fish. Future changes in the abundance of P. noctiluca, which is a highly venomous species, may therefore have both ecological and socio-economic consequences for different European countries.
Read more: Licandro, P., Conway, D. V. P., Daly Yahia, M. N., Fernandez de Puelles, M. L., Gasparini, S., Hecq, J. H. , Tranter, P. and Kirby, R. R., 2010. A blooming jellyfish in the northeast Atlantic and Mediterranean. Biology Letters, 6(5): 688-691.
Contact at SAHFOS : Priscilla Licandro
(left) Average monthly frequency of cnidarian jellyfish in CPR samples from (a) North Sea and (b) Northeast Atlantic from 1958-2007 and (right) the jellyfish Pelagia noctiluca.
