Why Are Thousands Of Pink Jellyfish Taking Over This Deserted Beach In The Philippines?

The jellyfish bloom captured in El Nido photographed on April 1. At the time of publication, the bloom event has now occurred for more than a week. Sue Muller Hacking

Drifting tentacle-to-tentacle, thousands of bright pink jellyfish are taking over the ocean surrounding the island of Palawan in the Philippines as the normally packed white sand beaches are left empty due to the coronavirus lockdown.

The massive jellyfish bloom was captured in a March 23 video by Sheldon Rey Boco, a researcher and co-founder of the Philippine Jellyfish Stings Project. The strawberry-pink jellyfish are thought to be a species known as Crambione mastigophore, or tomato jellies.

Boco told IFLScience that there is "current and sensationalized misconception in the media, and even in the scientific literature, that climate change, and other human stressors, are causing the increase of the size and frequency of jellyfish blooms."

"This misconception needs to be corrected. We need more tests and research to be able to make conclusions about this phenomenon," he said. 

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These cyclical events are impacted by a number of environmental factors, none of which are COVID-19 related, as some reports have suggested the jellies are swarming to the now-empty waters. Boco has been recording the occurrences of jellyfish and their bloom events in the Philippine archipelago and was made aware of the large Palawan bloom when the Philippine Department of Environment asked him to study its causes and effects. A jellyfish bloom is an abrupt or unusual – and sometimes normal – appearance of relatively large numbers (hundreds, thousands, or more) of medusae of a jellyfish. This means that in other times, days or months, medusae populations are fewer or nonexistent. Blooms can occur in almost every oceanic region. 

More importantly, Jellyfish blooms are not abnormal and previous reports detail events that extend for “miles and miles”. 

“If the question is: is this because people aren’t at the beaches? The answer is no,” Molly Zaleski, a marine biologist in Alaska told IFLScience. “These jellies, and a lot of other jelly species, sometimes just have massive blooms that are often more related to weather and ocean conditions.”

Such blooms are associated with seasonal changes in the ocean, like temperature or salinity, according to a study published in the journal Jellyfish Blooms.  

“Jellyfish blooms are a result of warmer water. There’s a seasonal variation of this, so spring and summer can cue a bloom but there are more [blooms] more happening now because of warmer waters in general,” said Zaleski. Other human-influenced impacts like fishing and eutrophication may also help to explain jellyfish blooms.

Higher temperatures speed jellyfish production and extend the reproduction season, notes Columbia University in a blog post. Blooms can last anywhere from a few days to several months, varying with species or location of that species. “Busts,” or the fall of the number of medusae, happens after a bloom event and many medusae can be stranded on the beach.  

It is probably best to avoid the waters of Palawa while they are jelly-filled. This particular species can "definitely" inflict harm to people, but not lethal stings. Boco notes that tomato jellies are venomous and "possibly painful." 

A mass stranding event of Crambione mastigophora in Western Australia. Springer

 

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