Tel Aviv, Israel – Two new studies from Tel Aviv University identify pathogens, storms, and extreme temperatures as the main forces behind mass mortality events in sea urchins, while also unveiling a COVID-style underwater swab that allows non-invasive genetic sampling.

The first study, published in Biological Reviews, analyzes 110 documented die-offs recorded between 1888 and 2024. Most reports came from the Northern Hemisphere, especially the United States, Western Europe, and Japan.

Researchers found that 33% of events were caused by pathogens. Another 25% were linked to catastrophic conditions such as storms and oxygen loss, while 24% stemmed from extreme temperatures. Algal blooms triggered 11% of events, and 7% resulted from human impacts such as pollution and habitat destruction.

“For each mass mortality event, we mapped where and when it occurred, which species were affected, and what the causes were,” said Dr Omri Bronstein. He noted that many modern die-offs match this pattern, with pathogens driving events from the Caribbean to the Red Sea and the Indian Ocean.

In 2023, Dr Bronstein identified a mass death of long-spined sea urchins along the Red Sea coast caused by the same ciliate parasite previously responsible for a Caribbean collapse. The outbreak has since spread to the Indian Ocean, returned to the Caribbean, and is now considered a global pandemic.

Sea urchins are vital to coral reefs because they graze algae that can overwhelm corals. Past die-offs, such as the 1983 Caribbean event, triggered long-lasting ecosystem collapse. Similar patterns are now appearing in Eilat, Sinai, and beyond, with some sites seeing 100% mortality in under 48 hours.

To address sampling challenges, a second study published in Molecular Ecology Resources introduces a simple underwater swab developed by graduate student Mai Bonomo and Dr Bronstein.

The tool works like a COVID test: the researcher swabs the animal’s surface, then inserts the swab into a sealed tube containing preservation liquid. Dozens of samples can be collected in a single dive without harming the animals.

The kit has been tested in Djibouti, Réunion Island, and the Gulf of Eilat. Samples remained stable for months without refrigeration and enabled extensive genetic analysis, leading to the discovery of several new species and updated classifications.

Keywords
seaurchins, massmortality, pathogens, extremetemperatures, telavivuniversity, redsea, indianocean, caribbean, coralreefs, geneticsampling

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