Long-spined sea urchins: Diadema antillarum

Since February 2022 there have been reports of Long-spined sea urchin (Diadema) die off from a number of islands in the Caribbean, including St. Eustatius, St. Maarten, Saba and Curaçao. Marine Protected Area authorities within the Dutch Caribbean region are concerned these events could be echoing the massive die-off of sea urchins that occurred in the 1980s which almost completely wiped out the Caribbean long-spined sea urchin populations. A new edition of the Dutch Caribbean Nature Alliance (DCNA) Bionews, a free digital newsletter, draws attention to the current state of the die-off, what is being done to restore these populations and what you can do to help.

Long-spined sea urchin facts

Diadema antillarum, also known as the lime urchin, black sea urchin, or the long-spined sea urchin, is a species of sea urchin in the family Diadematidae.

This sea urchin is characterized by its exceptionally long black spines. It is the most abundant and important herbivore on the coral reefs of the western Atlantic and Caribbean basin.

When the population of these sea urchins is at a healthy level, they are the main grazers which prevent algae overgrowth of the reef.

Long-spined sea urchins populations are in trouble | Dive News Curacao
Dead and dying long-spined sea urchins. Photo credit: Alwin Hylkema- all rights reserved

The Importance of Long-spined sea urchins

Long-spined sea urchins play a critical role in maintaining healthy coral reefs, which are essential for coastal protection and a crucial source of income for people in the Dutch Caribbean as they are a magnet for tourism. Long-spined sea urchins help sustain the delicate balance within the reef by grazing on algae, an overabundance of which can damage coral.

Caribbean-wide Disease

In the mid-1980s, a disease swept through the Caribbean wiping out nearly the entire sea urchin population. In mid-February 2022, reports started emerging about new extensive die-off events in the Caribbean region. Reports from within the Dutch Caribbean first came in on March 14th from the island of St. Eustatius. Follow on reports from the remaining Dutch leeward islands of Saba and St. Maarten soon followed. In Curaçao, the first sightings of diseased long-spined sea urchins were reported in early June. Two weeks later, more than 90% of the surveyed populations had disappeared.

Long-spined sea urchins Workshop

In April, DCNA, together with the University of Applied Sciences Van Hall Larenstein (VHL), hosted a Diadema Restoration Workshop. This workshop gave researchers and park authority managers a comprehensive view of the overall situation of the long-spined (Diadema) sea urchin in the Caribbean, including the current die-off events and restoration techniques.

You can help

Citizens and tourists can also help track sea urchin health in the Caribbean by adding their observations of healthy, sick or dead long-spined sea urchins. These reports will help park authority managers to determine the causes and work on restoration approaches.

You can report your sightings by visiting the AGRRA website or contact your local Park Management Organization.

Other advice to prevent spreading the disease:

  • Wash dive gear in lots of fresh water and let sun-dry
  • Dive on uninfected sites before (known) infected sites
  • Do not step on them or (re)move them: Alive or dead

Learn more about Long spined sea urchins

Learn more about the current state, what is being done to restore Long spined sea urchins populations and what you can do to help by reading DCNA’s latest edition of Bionews, DCNA’s free digital newsletter.

DCNA’s newsletter BioNews is kindly funded by the Ministry of Agriculture, Nature and Food Quality (LNV) and DCNA’s activities by the Dutch Postcode Lottery.

About the Dutch Caribbean Nature Alliance

The Dutch Caribbean Nature Alliance is a nonprofit organization created to safeguard nature in the Dutch Caribbean through supporting Protected Area Management Organizations.

DCNA’S NETWORK – The six islands of the Dutch Caribbean

The Dutch Caribbean consists of the Windward Islands of St. Maarten, Saba, and St. Eustatius and the Leeward Islands of Aruba, Bonaire and Curaçao. The pristine nature of the Dutch Caribbean contains the richest biodiversity in the Kingdom of the Netherlands. The diverse ecosystems are a magnet for tourism and at the same time the most important source of income for residents of the Dutch Caribbean. Nature on the islands is unique and important but it is also fragile.

The lack of sustainable funding, policy support and adequate spatial planning pose the most significant threats.

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