The vibrantly colored coral reefs of the Red Sea are an underwater paradise, home to amazingly beautiful fish and an amazing array of other marine life.
Despite the effects of climate change, these reefs have shown remarkable resilience to warming ocean temperatures.
But now the decline of the sensitive sea key species has created a new threat, as this precious habitat is threatened by rapidly growing green algae.
The damage to tourism can be devastating.
Israeli researchers first noticed the death of Black Sea divers near the southern city of Eilat earlier this year.
The spiny creatures – up to 50cm long defensive spines – are known to scuba divers and snorkelers flocking to the Gulf of Aqaba. They partially carpeted the region’s coastal reefs.
New surveys suggest a 90% decline in Jordan’s Aqaba resort, mass extinctions in Egypt and losses in Saudi Arabia are thought to be dependent on aquifers.
“We know it affects pathogens,” said Dr. Omri Bronstein of Tel Aviv University, putting a dead Black Sea fish—its body the size and shape of a flat tennis ball—into my hands.
He said there are visible signs of the disease, which paralyzes the spines and tiny limbs of the sea.
You see tissue loss, which we call necrosis, until you have a bare skeleton. And their death is very quick. The entire process takes 48 hours.
Sea algae vs coral
Videos captured by scuba divers show how contaminated black sea urchins are swarmed by invertebrate predators.
Perhaps the movement of fish and people, especially shipping, helped spread the disease.
Estimated to be more than 5,000 years old, there could be profound ecological impacts on one of the world’s oldest reefs in the Red Sea.
The sea keys play an important role in helping the coral larvae to stabilize and grow, as well as by feeding on algae, blocking sunlight and keeping it out of control.
“Algae and corals are always competing for space,” explains Omri Omesi, a marine curator at the Israel Parks and Nature Authority in Eilat.
Seaweed spreads very quickly once the frogs are gone: “Seaweed can spread faster than corals. As we know, corals grow on average 1cm in a year. Seaweed grows 1cm a day!”
To illustrate how quickly the disease spread, he tells a personal story of taking a diving vacation in Nuweba, Egypt, after he began monitoring the damage on the Black Sea coast, 80 kilometers to the south. North of the Gulf of Aqaba.
He remembers seeing thousands of black seafarers in Egypt and thinking “everything might be alright”.
“But after two weeks, the people there told me that if I went back to Nuweba, I would not find a single one.
Dr. Mahmoud Hanafi, a marine biologist at Suez Canal University, has been conducting his own research on Egypt’s southern Red Sea coast.
“Before, you would easily get 20 to 30 per square meter (10.7 square feet),” he tells me. “Now, from all the places I’ve seen north of Hurghada to south of Marsa Alam, the black sea crest is gone. I haven’t been able to find a single specimen.”
He said this shows that the species is disappearing in the area.
Other nearby countries have also seen dramatic declines in deaths. These include Jordan and Saudi Arabia, which covered 13 places He scored 113 on the long beachAlthough the result has not yet been officially announced.
After reports of sea urchin deaths near Muscat, Oman, fears have been raised that the trend could spread to the Arabian Gulf. The BBC was also told of the casualties on the Indian Ocean coast of Somalia.
Opinions differ about possible outcomes.
Scientists I spoke to in Egypt and Jordan were concerned that their populations do not yet appear to be affected by the loss of sea dogs. Other marine animals suggest that they support corals.
Other experts fear a repeat of what happened 40 years ago in the Caribbean, when a pathogen killed up to 99 percent of closely related sea urchin species. A thriving coral reef turned into an algae field.
The effect on the Red Sea may not be apparent until winter, when the algae bloom naturally.
Back in Dr. Bronstein’s lab in Tel Aviv, the race is on to identify exactly what kills the Black Sea urchins. One method they are using is to study environmental DNA, which they accidentally sampled from Eilat’s water when the pathogen first appeared.
“This is considered a treasure because it is really a black box of this phenomenon. We have to solve it now,” said Dr. Bronstein.
There are other glimmers of hope.
For almost a decade, the Tel Aviv team has been studying black sea urchins in the eastern Mediterranean since they appeared as an invasive species from the Red Sea.
While these populations—mainly seen as pests—have been hit first by recent die-offs, there are some healthy pockets of livestock that remain in captivity to eventually be repatriated.
In addition, a few young crabs appeared in the Gulf of Aqaba.
While their respective countries are taking steps to curb overfishing and pollution, which pose their own threats to coral reefs, Dr. Bronstein sees encouraging cooperation in this politically complex region where Saudi Arabia and Israel have no formal ties.
“The distance between Israel, Jordan, Egypt and the far south is actually not underwater,” Dr. Bronstein said.
He also said that although the cooperation is often not made public, countries are exchanging information and working together better.
Despite the many divisions of the countries bordering the turquoise waters of the Red Sea, the fate of the Black Sea reflects their shared desire to protect this unique marine environment.