The Department of Fisheries (DOF) has received reports of an apparent mass die-off event of Diadema antillarum, or as known locally, the (Long-spined) Black Sea Egg, from the neighbouring islands of Saint Vincent and the Grenadines, Antigua and Barbuda, Dominica, St Thomas, Saba and Statia.
The Department would be grateful for your support in monitoring the progression of this event in Saint Lucia. We ask that any sightings of dead and/or dying (Long-spined) Black Sea Eggs are reported to the DOF immediately.
According to the Department of Fisheries, this current die-off follows similar patterns to that of the early 1980s Diadema antillarum die-off, in which there was 95-99% mortality of the Diadema population throughout the Caribbean. The original cause of the 1980s die-off was not determined, however, losing this keystone species was devastating. Therefore, it is important to track the progress of this mass mortality event in the region and attempt to mitigate the spread of this phenomenon in Saint Lucia.
Sea Eggs, or Sea Urchins are herbivores, and graze on algae on the reef, providing vacant space for coral to settle and grow. Too few herbivores can lead to algae overgrowth which may suffocate coral, killing them. In extreme cases, this led to an algae-dominated reef system, instead of a coral-dominated system like the coral reefs we know and love. Sea urchins thus play an important balancing act in maintaining reef health.
Stages of Diadema antillarum Mortality: • Healthy: no visible injury or symptoms, intact spines; normal spine movement when stimuli is received • Sick: Several signs of illness occur over time, although they progress rapidly (1-2 days), excess mucus on spines; spine movement may appear normal, loss of the use of tube feet, unable to attach to the substrate; may float in the water; Spine movement less active – spines may not respond to touch as quickly. Loss of spines; tissue may slough off; majority of urchins present affected. • Dead: may/may not have visible injury; no movement of spines at all when prodded; not attached to substrate; skeleton is exposed with loss of spines; completely white skeleton with no spines; numerous dead urchins.
Sightings of any nature are to be reported to the Department of Fisheries by email at [email protected], WhatsApp at 731-3673, or telephone at 468 4135/4631. Grateful if you could provide: the date, location, water depth and number of dying and/or dead (Long-spined) Black Sea Eggs seen, and if possible, pictures.
* cover image by https://www.institut-paul-ricard.org/en/especes_aquarium/black-sea-urchin/