Sea urchins facing fatal mystery threat

| 19/04/2022 | 8 Comments
  • Cayman News Service
  • Cayman News Service
  • Cayman News Service

(CNS) The long-spined sea urchin (Diadema antillarum) is experiencing another high mortality event throughout the Caribbean, and although it may not have reached the Cayman Islands yet, the Department of Environment is asking people to report any sightings of sick or dead urchins in Cayman waters to help the scientists collect data.

The first reports of distressed urchins were in St Thomas USVI in early February, but by early March urchins in Jamaica were also impacted. In the last few weeks Mexico, Dominica and St Vincent have also reported deaths, but at this stage no one knows what is causing it.

A Diadema Response Network has been formed across the region to track and investigate the cause of this mortality event, which comes almost 40 years after the last mass die-off of these important marine creatures, which happened suddenly with no definitive cause.

The urchins were brought to the brink of extinction by the 1983-1984 mortality event from a still a mysterious water-borne pathogen. To this day the population around the Caribbean is about 20% of pre-1983 numbers.

DoE Senior Marine Researcher Dr Croy McCoy explained that sea urchins, especially the long-spined sea urchins, are considered a “keystone grazer”, tasked with controlling algae growth on our reefs.

“Long-spined sea urchins play an important role in removing algae and maintaining the health of our coral reefs ecosystem. They are the lawnmowers of our coastal seas, clearing real estate so that other organisms, like baby corals, can attach themselves and grow,” he explained.

This latest potentially devastating threat comes at a time when reefs are already under enormous threat from a myriad of issues, from climate change to over-fishing.

“It is sad to see yet another high mortality event in the Caribbean region of this critically important urchin for the ecological function of our coral reefs. Furthermore, the reported rate at which large numbers of these urchins are now dying resembles the mass mortality 40 years ago,” Dr McCoy said.

There have not been any reports of unusual deaths of these sea urchins in the Cayman Islands yet but the reefs are currently battling stony coral tissue loss disease, which made its way across the Caribbean since it was first reported in Florida in 2014. Once here, it took less than a year to encircle Grand Cayman.

SCTLD Response Team Coordinator Tammi Warrender urged the community to help address the new threat to the local urchin population, and in turn the reefs, by letting the DoE know what they see.

“Reports from the public are essential so that we can respond immediately to this threat and collect, organise and share data with the wider scientific community to help find possible solutions,” she said. “The most important thing the community can do now is to report ‘what, when and where’ they see anything unusual, particularly a dead or a group of dead sea urchins. Reports of healthy sea urchins will also be useful for our response.”

Sick or dead urchins might be unable to attach by their feet, so they may be found floating or have lost spine movement or spines. Dead urchins may also have the skeleton exposed with a loss of spines.

People diving, snorkelling, out on their boats, fishing or just walking the beach are encouraged to download the DoE’s EpiCollect app ”Urchin Health Cayman” to submit reports quickly and efficiently.

The public can also WhatsApp or text a report to 926-0680 or email

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Category: Marine Environment, Science & Nature

Comments (8)

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  1. Anonymous says:

    It has nothing to do with development. It happened before in the early 80’s. It was happening throughout the Caribbean and as far north in Florida.Than they came back from the brink of extinction. Nobody knows why it really happened and how they came back. Maybe God?

  2. Curious says:

    Can any informed minds out there (operative word here being “informed”) shed some light on why Cayman sea urchins cannot be sustainably raised, harvested and consumed, similar to sea urchins in other parts of the world (i.e., Santa Barbara uni)? I’ve always wondered why this isn’t a thing here (other than the fact that, historically, Caymanians don’t eat sea urchin).

  3. Anonymous says:

    This is probably one ice particle on the tip of the ice-berg and most still choose to look the other way razing the landscape, poisoning the atmosphere, wiping out species, and think we are sacrosanct from those actions. Might as well go ahead and build those pickle-ball courts, the shortsightedness and attainment for self marries well with our ignorance.

  4. Elvis says:

    Horrible things should be banned from the ocean .
    Lethal in your feet

  5. Anonymous says:


  6. Anonymous says:

    No matter how one wishes to frame it, our planet is severely damaged. The signs are decades-old, and so is the lip service.

    Between the impacts of climate change (can’t be denied), pollution and overfishing, sea life is disappearing.

    • Anonymous says:

      I know they have their place in the ecosystem but as one who remembers when they were everywhere and has had one stuck in my foot its hard to wish for their return.


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