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CRITTER: More jellyfish on our beaches lately due to Kona winds

Hawai‘i has more than 15 jellyfish species that float around our islands and sometimes show up on our beaches. The box jellyfish is a small stinging species that often shows up on our South Side beaches and stings swimmers. Jellyfish alerts are common when the box jellies are spotted.

Pololia is the Hawaiian name for jellyfish, but we also have floating stinging siphonophores like the Portuguese man-of-war and the small, by-the-wind sailors that sometimes show up on our beaches in huge numbers! Not all of our jellyfish sting, so it is good to know which ones are which and you can Google “Hawaiian jellyfish” to see lots of good pictures.

We all have heard the box jellyfish alerts that are posted from time to time along our south shores especially in the Waikiki area where hundreds of people get stung every year. Most jellyfish stings are nonthreatening and will cause localized pain for several hours. Applying vinegar to a jellyfish sting helps, but some people who get stung by the man-o-war need medical attention because the pain can be extreme. While surfing at Makaha on the O‘ahu west side, I paddled into a man-o-war and ended up in the hospital for half a day.

Jellyfish often float on currents that are blown by the wind. Certain weather conditions make it easy to predict when these jellyfish may come close to shore, but lately our weather patterns have been changing and many of the stinging jellyfish have been showing up on the North Shore also. In one snorkel session at ‘Anini Beach on Kaua‘i’s North Shore, I counted over 12 man-o-war floating right by everyone snorkeling. There is a reason why we are now seeing jellyfish all around the islands more often.

For the last 10 years, Hawai‘i has had a warm water current coming down from our northern seas and a warm water current coming up to Hawai‘i from the southern seas.

NOAA predicted several years back that these currents will meet up in Hawai‘i causing a slight increase in sea water temperatures. This does not seem like much of an issue, but we are seeing the outcome of this warm water almost everyday now.

The warmer water tends to create less of a temperature difference between the sea and land, and that causes our normal trade winds to be less common. We are now having about 30 percent more calm Kona wind days than we had 10 years ago, which causes an onshore wind along the North Shore. Us surfers are seeing this wind change right now, as we are having less good offshore wind days along the North Shore and more onshore wind days, which affects the quality of the surf!

It is a simple cause and effect happening. The ice caps are melting at an accelerated rate, causing ocean currents to change, which is creating more Kona winds and more jellyfish on our North Shore beaches. With our changing wind patterns and changing currents, it’s no telling what may show up in Hawai‘i in the future.

We believe that the changing currents may even bring more venomous sea snakes to Hawai‘i because the yellow bellied sea snake often drifts on the same currents as the jellyfish and shows up in Hawai‘i from time to time. I will talk about the rare sea snake sightings in Hawai‘i that may become more common in an article to come.

You can watch some of our Hawaiian jellyfish in action in my underwater marine life educational series on my YouTube at Underwater2web.


Terry Lilley is a marine biologist living in Hanalei Kaua‘i and co-founder of Reef Guardians Hawai‘i, a nonprofit on a mission to provide education and resources to protect the coral reef. To donate to Reef Guardians Hawaii go to
Source: The Garden Island

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