Sea urchins are reportedly under threat from changing sea conditions across the world.

Two new studies from Tel Aviv University identified pathogens, storms, and extreme temperatures as the main drivers of mass mortality events in these marine invertebrates, while also unveiling a COVID-style underwater swab that allows for non-invasive genetic sampling.

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

Researchers found that 33 per cent of events were caused by pathogens. Another 25 per cent were linked to catastrophic conditions such as storms and oxygen loss, while 24 per cent stemmed from extreme temperatures.

Algal blooms triggered 11 per cent of events, and seven per cent resulted from human impacts such as pollution and habitat destruction.

Lead researcher Dr Omri Bronstein said: 'For each mass mortality event, we mapped where and when it occurred, which species were affected, and what the causes were.'

He noted that many modern die-offs followed the same 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 otherwise 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 per cent mortality in under 48 hours.

To address sampling challenges, a second study, published in Molecular Ecology Resources, introduced 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.

Footage shows a researcher swabbing a sea hedgehog in an underwater tank to demonstrate the technique.

The kit has been tested in Djibouti, Reunion 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.