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Dangerous jellyfish population is booming in Hawaii, new study finds

The venomous jellyfish, which can be difficult to spot in the water, shut down a famous beach recently and researchers believe they know where the dangerous creatures have been making their homes.

By Allison Finch, AccuWeather staff writer

Published Jun 9, 2022 6:00 AM EDT | Updated Jun 8, 2022 1:40 PM EDT

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Andrew Merry/Getty Images

One of nature's most dangerous sea creatures, known as the box jellyfish, is taking over popular beaches along the south shore of Hawaii's island of O'ahu. According to National Geographic, the box jellyfish's venom is considered the deadliest in the world. With an ever-growing population in Hawaii, beachgoers might have to think twice about entering the water.

A new study published by researchers with the University of Hawaii examined the behavior of these jellyfish and why their population has significantly increased since the 1980s

The decade-long study was led by longtime local jellyfish researcher Angel Yanagihara, an associate research professor at the university's school of ocean and earth science and technology and the John A. Burns School of Medicine. It specifically monitored the Alatina alata species of box jellyfish, which is found in Hawaii and other tropical waters in the Pacific Ocean and the Caribbean Sea.

Of the more than 40 species of box jellyfish, the Alatina alata species is the only one whose migration and spawning patterns are like "clockwork," and follow the lunar cycle.

According to the peer-reviewed University of Hawaii (UH) study, published in the June issue of Reginal Studies in Marine Science, researchers found that in order for these gelatinous creatures to spawn, they swim toward shore on the nights in the lunar cycle when there's a long period between twilight and moonrise, which is typically eight to 12 days after a full moon.

"The period of the lunar cycle with a key number of hours of darkness or the 'absence of light' cues mature animals to specifically swim to the shoreline to spawn," Yanagihara told the Honolulu Civil Beat, a local news organization.

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Since the 1980s, both the numbers and frequency of this species of box jellyfish have significantly increased, especially around Waikiki Beach, a famous surfing hotspot south of Honolulu. According to the report, researchers link the population growth of these jellyfish to a series of shipwrecks off Waikiki Beach.

For the past 30 years, these sunken metal ships have remained just off the coast, at the bottom of Mamala Bay, becoming artificial reefs for nearby wildlife, including the jellyfish, which has allowed the population to explode.

"You suddenly have all this new real estate to attach to," Yanagihara said, noting that similar underwater wrecks in other parts of the world have been linked to "unanticipated blooms" in local jellyfish populations.

According to the study, the depletion of jellyfish predators, such as certain fish and turtles, has been another cause for the increased jellyfish population around Hawaii.

Waikiki Beach is a popular tourist destination, but the increasing population of box jellyfish poses a "major public health and safety concern," according to the study. Recently, the box jellyfish washed ashore in such alarming numbers that officials closed the beach as a precaution. The beach was reopened once it was deemed safe for swimmers to return to the water.

To protect beachgoers, the Hawaii Beach Safety organization issues box jellyfish warnings. When a significant number of jellyfish are found on a specific beach or observed in the surrounding waters, a warning is issued to alert beachgoers that there is a high probability that person who enters the water will be stung.

Since the box jellyfish is translucent, it can be difficult to spot in the water. Symptoms of a box jellyfish sting can vary depending on the severity of interaction with the sea creature. Some of the first symptoms include a severe stinging or burning pain and a red skin wound that looks like caterpillar tracks, according to Healthline. If stung, it is important to seek immediate medical attention as soon as possible to stop the spread of venom to other parts of the body.

See also:

NASA satellite captures images of 'Sharkcano' eruption
Shark sightings in Northeast waters put beachgoers on high alert
Sinking mid-Atlantic coast will increase impacts of rising sea level

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