By Jorge J. Muñiz Ortiz
San Juan, Apr 20 (EFE).- The deaths of hundreds of black sea urchins (Diadema antillarum) in a large expanse of the Caribbean Sea has generated alarm among scientists, who are investigating the causes and fear a repeat of a mass die-out that occurred in the early 1980s.
The reason for this current phenomenon remains unclear at the moment.
But the Atlantic and Gulf Rapid Reef Assessment (AGGRA) Program, an initiative that works to conserve coral reef ecosystems, warns that the rapid pace with which those small, spiny, seafloor-dwelling animals are dying rivals what happened in 1983.
Maria Vega Rodriguez, a marine biologist with the Puerto Rico Department of Natural and Environmental Resources’ Coral Reef Conservation and Management Program, told Efe the first reports of a sea urchin die-out date back to mid-February near Charlotte Amalie Harbor in St. Thomas, part of the United States Virgin Islands.
Scientists on that island called an emergency meeting, and investigators were brought in to “verify whether it was a localized event or not,” Vega said.
Diadema antillarum, also known as the long-spined sea urchin, is one of the most important coral-dwelling herbivore species in the Caribbean because of its role in removing algae and maintaining open space for coral growth.
A month after the discovery of the first dead sea urchins, scientists received reports of similar mortality events off other Caribbean islands such as Jamaica, Dominica, St. John, Saba, St. Eustatius and Saint Vincent and the Grenadines.
Some 500 black sea urchins were found dead in some of those territories, particularly in the Eastern Caribbean region, Vega said.
Members of the AGGRA Program then visited those affected places and certified the deaths of large communities of those marine echinoderms.
The signs indicating those sea urchins are ill or have died include the loss of control of their tube feet, the muscles that protrude from their spines and allow them to breathe, attach to rocks or coral and move along the sea floor, followed by the loss of their spines or tissues.
As part of its efforts, AGRRA has formed the collaborative, region-wide Diadema Response Network to track and try to understand the causes of the die-off of Diadema antillarum (and possibly other sea urchin species).
“This network helps us as investigators to come together from our different microbial or macrobial perspectives of the waters (and) observe via satellite their changing temperatures and possible traces of oil,” Vega said.
“The idea is to collect healthy or dead sea urchins and use those samples to conduct compositional analysis and pathological analysis,” she added.
The primary goal of the marine scientists and other experts is to prevent the sea urchin die-off from spreading to other parts of the Caribbean.
“It was so catastrophic in the 1980s that we’re still recovering from that event … so now we’re putting all of our efforts into finding out the causes,” Vega said.
The reason for that earlier die-off was never determined due to inadequate sampling, AGRRA says on its website.
“Few Diadema populations have since fully recovered, resulting in algal-dominated states on many of the region’s reefs,” it adds. EFE