The global study by Prof. Omri Bronstein of Tel Aviv University found that after a mass mortality event in mid-2022 in the Canary Islands, the long-spined black sea urchins of the genus Diadema are no longer able to produce offspring.
The research spans the globe של Prof. Omri Bronstein from the School of Zoology in the George S. Wise Faculty of Life Sciences, and the Steinhardt Museum of Nature A Tel Aviv University study, which is tracking the wave of mass sea urchin deaths around the world, has revealed new and particularly worrying findings: For the first time, evidence of a complete extinction of sea urchins has been found in the Canary Islands. The study revealed that the genus Diadema (the long-spined black sea urchins familiar to us all) is no longer capable of producing offspring at this site – a finding that likely indicates complete local extinction.
The 'missing link' in the geographic path of the disease's spread
The study was led by Prof. Omri Bronstein in collaboration with researchers from Spain and the Canary Islands. The scientific article was published in the journal Frontiers in Marine Science.
Prof. Bronstein describes the sequence of events in recent decades: "In 1983-4, a mass mortality event of sea urchins of the genus Diadema was first identified in the Caribbean islands in the western Atlantic Ocean. The mortality of the urchins led to a significant ecological change in that area: the disappearance of sea urchins, the main algae eaters in the habitat, caused the formation of extensive algae fields that blocked sunlight, causing extensive and irreversible damage to the coral reefs in the area. In 2022, another mortality event occurred in the Caribbean, and for the first time, the pathogen that causes the fatal disease was also identified. This epidemic spread to the Red Sea in 2023, and in 2024 it was also detected in the Indian Ocean."
The current study identified a mortality event in the Canary Islands off the coast of Morocco in the eastern Atlantic Ocean, which actually occurred as early as mid-2022. According to the researchers, this is the 'missing link' in the geographical path of the disease's spread. The study also revealed a particularly disturbing finding, which likely indicates a complete local extinction of the species in the Canary Islands. The study was based on observations by local residents (citizen science), along with surveys, analysis of satellite data (remote sensing), and collection of samples from the seabed by the research team.
"Sea urchins reproduce by releasing sperm and eggs into the sea water, and during fertilization, millions of embryos are formed in the water. After a few weeks, the embryos settle on the bottom and turn into young urchins in a process called 'recruitment.' In this study, we discovered that in the Canary Islands there are no more young urchins on the bottom, meaning that this 'recruitment' process is no longer occurring since the widespread mortality event that occurred there," explains Prof. Bronstein, continuing, "This means that the urchin mortality is so widespread that the species is unable to produce a successor generation, and it may have disappeared permanently from the ecosystem in the area."
Will the sea urchins on the shores of the Red Sea and Eilat also become extinct?
The researchers add that sea urchin populations are known to be volatile. They often decline and then recover, but this time the situation seems to be particularly serious and appears to be an extinction event. The researchers fear that the pattern revealed in the Canary Islands mortality event will also be realized in other areas around the world where sea urchin mortality events of unprecedented magnitude have been discovered in recent years, including those along the Red Sea coast and the coral reefs of the Gulf of Eilat.
"In this study, we identified a mass mortality event of sea urchins that occurred in mid-2022 in the Canary Islands. Following the event, it became clear that the affected species no longer reproduces in this area, which likely indicates a complete local extinction, which is expected to have significant ecological consequences. A likely outcome would be the uncontrolled growth of algae that would affect the entire system, although it is difficult to predict in what way," concludes Prof. Bronstein.
Prof. Omri Bronstein is a marine biologist who works in molecular ecology and understanding the processes that lead to the creation of new species, and a senior faculty member at the School of Zoology in the George S. Wise Faculty of Life Sciences and the Steinhardt Museum of Natural History at Tel Aviv University.
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