The worst jellyfish invasion for two years has led to authorities closing beaches across Spain, leaving holidaymakers shocked. Swarms of Mauve Stinger jellyfish threatened tourists on the beaches of Alicante in the northern Costa Blanca with the Red Cross in Denia treating 50 people in just half an hour.

On Sunday alone, the number of people stung by jellyfish throughout Spain was well over 700, reported the Associated Press. Fears are rising that the affected number of people could surpass the 2008 record, when 4,000 people had to be treated for jellyfish stings.

Spain’s Ministry of Environment said in a statement: “The exact reasons to explain jellyfish blooms are currently under research. They seem to be increasing in recent years and the most likely causes suggested are the decline of natural predators such as turtle and tuna; changes in climatic factors such as rainfall or global temperature; hydrographic peculiarities of the area, as well as pollution from land based sources.”

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