Fighting for the Future: Israeli Researchers Battle Unseen Epidemic Threatening Coral Reefs

Israeli scholars have made a startling discovery that is causing ripples of concern in the marine science community. Researchers from Tel Aviv University have found that an unknown epidemic is causing a massive die-off of black sea urchins in the Mediterranean Sea and the Gulf of Eilat, a critical blow to these vital marine ecosystems.

In a matter of months, the once-thriving population of black sea urchins in Eilat vanished. Such a rapid decrease in population has left only skeletal remains at once-thriving sites, an eerie testament to the severity of the epidemic. And this is not a localized issue; the epidemic’s effects have been observed in neighboring countries, including Jordan, Egypt, Saudi Arabia, Greece, and Turkey.

Sea urchins, especially the long-spined Diadema setosum, play a pivotal role in maintaining the health and balance of coral reefs. The sudden and drastic decrease in their population, the researchers warn, adds a new, unforeseen threat to the already critically endangered coral reefs. This is an event with no precedent in the recorded history of the Gulf of Eilat.

The current hypothesis suggests a pathogenic ciliate parasite, potentially spread from the Mediterranean to the Red Sea, is the cause of the epidemic. The situation has prompted the researchers to submit an urgent report to the Israel Nature and Parks Authority, and emergency measures to protect Israel’s coral reefs are currently being considered.

Dr. Omri Bronstein and his team from Tel Aviv University led the pioneering studies. Dr. Bronstein initially believed the sea urchin deaths could have been due to pollution, but after further research, the evidence pointed towards a rapidly spreading epidemic. It is a brutal disease, turning healthy sea urchins into skeletons within two days.

Bronstein’s research group has been studying the issue of marine invasions, focusing on species such as the long-spined Diadema setosum. These sea urchins are integral to the coral reef ecosystem as they keep algae growth in check, preventing it from overshadowing the corals that compete with them for sunlight. Unfortunately, these sea urchins are vanishing rapidly from the Gulf of Eilat and other parts of the Red Sea.

Reports of mass mortality first reached Dr. Bronstein from colleagues in Greece and Turkey, where these sea urchins had migrated, likely through the Suez Canal. Since 2018, the sea urchin population in the Mediterranean had been growing exponentially, reaching population explosion levels in Greece and Turkey. But just as the invasion research was concluding, reports of sudden extensive mortality began to emerge.

Although the extinction of an invasive species might seem advantageous at first glance, two significant risks are associated with this scenario. The effects of such mass mortality on local species in the Mediterranean are unknown. More critically, the close geographical proximity of the Mediterranean to the Red Sea increases the risk of the pathogen reaching the natural population in the Red Sea.

The mass die-off reminded researchers of the tragic loss of sea urchins in the Caribbean in 1983, a disaster that irreversibly changed a vibrant coral reef into an algae field. Unfortunately, the same pathogenic parasite identified in the Caribbean die-off is now suspected to be causing mortality in the Mediterranean and Red Sea.

Dr. Bronstein’s groundbreaking studies were the first to identify such mass mortality in an invasive species in the Mediterranean. He ended one of these seminal studies with a warning that the epidemic in the Mediterranean could spread to the nearby Red Sea, a prediction that has unfortunately come true.

The current situation requires immediate action to establish a broodstock population of these sea urchins, thereby ensuring their survival and the future of the coral reefs. Time is of the essence, as we need to preserve healthy individuals from the Israeli Mediterranean before the disease spreads from the north. This mission is challenging but necessary to safeguard this unique species and the future of coral reefs.