Mortality and skin pathology of farmed Atlantic salmon (Salmo salar) caused by exposure to the jellyfish Physalia physalis in Ireland.

In October 2019, during Tropical Storm Lorenzo, an unusual bloom of Physalia physalis (commonly known as the Portuguese man o' war) appeared on the west coast of Ireland. The jellyfish were observed aggregating in high numbers surrounding salmon pens on two Atlantic salmon farms with tentacles extending underwater through the nets into the pens. Acute skin lesions and mortality were reported as a consequence of exposure to P. physalis on both sites. The impact of noxious zooplankton species such as P. physalis may pose a significant and more frequent threat in future if increased adverse weather events continue to transport these and other jellyfish outside their normal range. This is the first published record of Physalia physalis causing mortality in cultured fish.

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

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.

Portuguese man-of-war (Physalia physalis) envenomation on the Aquitaine Coast of France: an emerging health risk.

CONTEXT: The Portuguese man-o-war is a cnidaria classically found in tropical waters. It can cause serious and even life-threatening envenomation in swimmers, surfers and seafarers. Presence of the Atlantic species Physalia physalis has long been reported in European coastal waters but was always an exceptional event. OBJECTIVE: To describe the experience of the Bordeaux Poison centre about Physalia stings since the first collective episode reported in 2008. METHODS: Clinical retrospective description of cases series of Physalia envenomations reported to the local poison centre from 2008 to 2011 inclusive. RESULTS: In the summer of 2008, multiple-case incident involving 40 victims were recorded on the same day on one beach in the Southern French Atlantic coast. The following year in 2009, no envenomation cases were reported in the same area, but in the next 2 years, numerous man-of-war envenomations occurred along the Aquitaine coast, that is, 154 cases in 2010 and 885 in 2011. Portuguese man-o-war stings led to severe manifestations with 15-20% of patients suffering of general symptoms that were sometimes severe enough to be considered as potentially life-threatening (8% of patients in 2011, most frequent signs: muscle pain and cramps with fasciculations, confusion and drowsiness, fainting, respiratory distress). No deaths due to Portuguese man-o-war envenomation were reported over the 4-year study period. CONCLUSION: The results suggest that national multidisciplinary summer surveillance program in the Aquitaine coast is required in order to provide alerts to the public, to better identify patients at risk for developing severe clinical symptoms, and hopefully to improve quality of health care.