Wageningen University and Research, and Van Hall Larenstein University of applied science together with international team of researches have located the cause of mass mortality among Caribbean Sea urchins of the species Diadema antillarum. Science advances, have published the research and findings.
Algae on the coral reefs are kept under control by these important grazers, commonly known as sea urchins. In 2022 much of the sea urchins of the species Diadema autillarum were found dead in the Caribbean Sea. The mortality has expanded and spread rapidly, maintaining in the US Virgin Islands in January 2022.
Once infected, up to 99% of the population died within a few weeks. Caribbean coral reefs, which are already under great pressure from climate change and other threats, adding this problem would prove catastrophic.
Urchins are the main control of algae overgrowth. Controlling the reefs of algae is vital for a healthy coral recruitment, as algae are intense competitors of Corals.
Diseased and healthy sea urchins were collected by the team of researches from many different Caribbean Islands. Ultimately the test conducted that Scuticociliates were responsible for the mass mortality. The results were compiled by comparing genetic material from healthy and diseased urchins, with a variety of potential pathogens. One ciliate (philaster sp) was known to be present in all sick urchins and absent in healthy urchins at other areas.
The pathogen was isolated and introduced to the healthy urchins in the lab, soon indicated signs of the disease. Consequently, the ciliates were found back in the sick urchins. Clearly apparent that ciliates were the primary pathogen causing the mass mortality.
The symptoms in diseased Diadema sea urchins in 2022, were found to be similar to those observed in the early mass mortality in the 1980’s. Loosing control of the tube feet, weakening spine response, followed by their loss and necrosis of the epidermis. These symptoms were observed in both laboratory and wild sea urchins.
Science advances, has now published the scientific paper which indicates an important first step in predicting and a possible prevention of such disease outbreaks in the future. Caribbean coral reefs survival depends greatly on the grazing activities of Diadema Sea urchins.
