Portuguese Man o'war: A growing threat to marine ecosystems and human health
MARE researcher Gisela Dionísio is co-author of the article ‘Unravelling environmental drivers and patterns of Portuguese man o’ war (Physalia physalis) blooms in two ocean regions: North Atlantic and the Southeast Pacific’, recently published in the Marine Pollution Bulletin of the Elsevier group. The study investigates how regional wind patterns, primary productivity and rising temperatures influence the occurrence of the Portuguese Man o'war in the North Atlantic (Azores) and the Southeast Pacific (Australian east coast). 
The proliferation of jellyfish has become a growing concern for marine ecosystems, human health and various economic sectors, such as fishing, aquaculture and tourism. In particular, the Portuguese Man o'war (Physalia physalis) is one of the most alarming species due to its great danger and increased frequency of occurrences.
In this context, the research group, of which Gisela Dionísio is a member, analysed the regional factors that influence the occurrence of this species, providing valuable information for the development of more effective management strategies. The team focussed on how wind patterns, primary productivity and rising temperatures affect the presence of the Portuguese Man o'war in the two regions under study.
The study concludes that the presence of the Portuguese Man o'war is mainly influenced by specific wind patterns and increased primary productivity. Using machine-learning models, which cross-referenced high-resolution environmental data with field observations, the researchers highlighted important regional differences. While the Azores have seen fluctuations in jellyfish populations over the last few decades, the Australian east coast has seen a significant increase in their presence over the last 30 years.
In addition, the models indicate that, due to climate change, jellyfish blooms may become even more frequent, with changes in temperature and ocean productivity potentiating this phenomenon due to climate change
This research provides a better understanding of the ecological factors influencing the Portuguese Man o'war, which can support the development of more effective coastal management strategies. Climate change, which intensifies the occurrence of P. physalis, will have more profound impacts on local ecosystems and economies.
The study was supported by the start-up MARE Naturalist, Science & Tourism, in partnership with the AtlanticNaturalist.org (MONIJELLY) project, which proposes an innovative alternative for funding research and creating synergies between the regenerative blue economy and research centres, using ecotourism as a driver for development.
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