Portuguese Man-of-War (Physalia physalis) in the Mediterranean: A permanent invasion or a casual appearance?

L Prieto,A Peliz,J Ruiz,D Macías

doi:10.1038/srep11545

L Prieto, A Peliz + Show 2 more

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https://doi.org/10.1038/srep11545

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Abstract

In 2010, the Mediterranean basin experienced Portuguese Man-of-War (Physalia physalis) swarms that had dramatic consequences, including the region’s first recorded human fatality attributed to a jellyfish sting. Despite the impact of jellyfish on coastal economic activity and the importance of the tourism industry for the Mediterranean region (accounting for 15% of global tourism), no scientific consensus has been achieved regarding the causes of this episode. Here, we analyse the meteorological and oceanographic conditions of the North-East Atlantic Ocean during the months previous to the appearance of P. physalis in the Mediterranean. We simulate the probable drift of Atlantic populations into the Mediterranean basin with a numerical model and compare model results with available observations. We conclude that the summer 2010 P. Physalis swarm was the result of an unusual combination of meteorological and oceanographic conditions during the previous winter and not a permanent invasion favoured by climatic changes.

Highlights

While swimming in the waters off the Italian island of Sardinia in August 2010, a woman suffered an allergic reaction and died after being stung by a Portuguese Man-of-War (Physalia physalis)[1]
A plausible explanation for the occurrence of the Portuguese Man-of-War within the Mediterranean Basin in summer 2010 is that specific climatic and oceanographic conditions during the previous winter in the North Atlantic favoured the transport of this jellyfish organism into the Mediterranean
The North Atlantic Oscillation index (NAO) is one of the major modes of variability in the Northern Hemisphere atmosphere[7] and is significant in winter (December to March) when it exerts a strong control on the climate of Western Europe by regulating the intensity of zonal winds and precipitation patterns[8]

Summary

Introduction

While swimming in the waters off the Italian island of Sardinia in August 2010, a woman suffered an allergic reaction and died after being stung by a Portuguese Man-of-War (Physalia physalis)[1]. P. physalis, a pleustonic colony of polypoid and medusoid organisms, is equipped with a potent toxin that is potentially deadly to humans[2,3] (more details in Supplementary Information). In addition to this isolated fatality, an unusual number of P. physalis sightings were recorded along the coast of the Mediterranean Sea, Iberian Peninsula (both along the Atlantic and Mediterranean coast lines) and Canary Islands (Fig. 1a, Supplementary Table 1) in the year 2010. The hydrodynamic model simulates water movement and physical oceanic conditions of the Gulf of Cadiz and Alboran Sea regions while the individual www.nature.com/scientificreports/. Model estimated beaching patterns of P. physalis were compared with available observations at both sides of the Strait of Gibraltar for winter/spring of year 2010

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