Long-spined sea urchins: no trouble but in trouble

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. This sea urchin belongs to the Diadema genus.

Importance for coral reefs

Long-spined sea urchins play a critical role in maintaining healthy coral reefs, which are essential for coastal protection. Moreover, they are 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, which in overabundance 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 14^th from the island of St. Eustatius. Reports from the other Dutch Leeward islands of Saba and St. Maarten soon followed. In Curaçao, the first sightings of diseased sea urchins were reported in early June. Two weeks later, more than ninety percent of the surveyed populations had disappeared. 

Diadema workshop

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

You can help

Citizens and tourists can also help by reporting their observations of healthy, sick or dead urchins in order to track sea urchin health in the Caribbean. 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 by contacting your local Park Management Organization.

Other advice to prevent spreading the disease:

• Wash dive gear in lots of fresh water and let it dry in the sun
• Dive on uninfected sites before diving on known infected sites
• Do not step on them or move them – alive or dead

More information

You can read more in the DCNA newsletter Bionews about the current state of sea urchin populations and what is being done to restore them.

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

Text: Dutch Caribbean Nature Alliance
Photos: Alwin Hylkema