Scientists find cyclical rise in box jellyfish - Hawaii News Now - KGMB and KHNL

Scientists find cyclical rise in box jellyfish, but humans also to blame

HONOLULU (HawaiiNewsNow) -

The number of box jellyfish is on the rise in Oahu's waters partially because of a recently discovered cycle, and also because of human activity, according to scientists who have been studying the stinging creatures.

Wednesday's closure of Hanauma Bay due to a jellyfish invasion is a case in point. More than 50 stings were reported in a two hour period. It was the fourth time the popular nature reserve has been closed due to jellyfish in the last 12 months, and the second time since January.

University of Hawaii biochemist Dr. Angel Yanagihara has been studying the jellyfish worldwide. She and her staff have been counting the jellyfish in Waikiki every month since 1998, and has discovered a decade-long cycle in their numbers.

"If you take ten or 12 years, you'll see a major peak, and then a trough, and then a peak again," said Yanagihara. "So 2013, 12, 13, 14, we're again at a peak."

However, the peak number of box jellyfish are even higher now than in the last peak period around 2001. Yanagihara said human activity is partially to blame.

"We had the molasses spill. We had the sewage spill. Al these nutrifications of Mamala Bay, which allow these small life forms to increase in number."

Overfishing in Oahu waters is another reason for the increase in the jellyfish population, Yanagihara said. 

And the seawalls along Kuhio Beach that keep tourists safe? "If the jellyfish were designing their perfect nursery, I don't think that they could design anything better than that, because basically these animals are coming in to spawn."

But where are the jellyfish when they aren't being a monthly nearshore nuisance? And why are they coming in about ten days after a full moon? Yanagihara said researchers are close to finding the answers to those questions as well.


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