Israeli and Australian researchers have discovered that rich and diverse communities of bacteria and invertebrates help corals thrive, a discovery that could help rehabilitate reefs damaged by climate change, pollution and overfishing around the world .
These findings echo the findings of a growing body of terrestrial research that shows the importance of microscopic creatures such as bacteria and fungi to soil and plant health.
The team of researchers designed terracotta tiles to replicate the complex 3D structure of natural coral reefs. They placed some tiles on a healthy reef and others on a damaged reef in the Gulf of Eilat, at the southern tip of Israel.
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During the six months spent underwater, the tiles were colonized by various reef invertebrates and bacteria. Then they were swapped. Tiles from the healthy reef were placed in the damaged reef, and vice versa.
Tiles like these, showing corals thriving on a healthy community of bacteria and invertebrates, were used for research off the coast of Eilat in southern Israel. (Credit: Meron Segev)
Two coral species were attached to the tiles and left in place for an additional six months, after which all tiles were tested for microbial life.
The researchers found that life was richer and more diverse on tiles moved from the healthy reef to the damaged reef.
Corals maintain symbiotic relationships with algae: the former provide them with shelter and the latter feed through photosynthesis.
Corals formed on tiles with the most vibrant communities of bacteria and invertebrates functioned better in these symbiotic relationships, with greater capacity for photosynthesis, and were less stressed.
Fish and corals in the Red Sea near the southern city of Eilat. (Credit: Prof. Maoz Fine)
“This innovative approach highlights the critical role of healthy reef ecosystems in restoring coral health and resilience,” said Natalie Levy, of Bar Ilan University, who led the research.
“The results highlight the potential of ecosystem transplantation as an effective and sustainable restoration tool that can be integrated with other coral restoration methods, such as coral gardening and artificial reefs,” he said. -she added.
Professor Oren Levy, also from Bar Ilan University, added that the research “advances our understanding of coral restoration and provides an invaluable tool to help resolve the current global coral crisis.” By using healthy ecosystems to regenerate damaged reefs, we can work to create more resilient and sustainable coral ecosystems that may one day recover from climate disruption and other threats.”
The researchers, who also include Professor Ezri Tarazi of the Technion (Israel Institute of Technology) in Haifa, in the north of the country, and Professor David Bourne of James Cook University and the Australian Institute of Marine Science , published their findings this month in the journal Nature Communications.
Although they cover less than 1% of the ocean floor, coral reefs are home to more than a quarter of marine life.
However, due to climate change, overfishing and pollution, more than half of the planet’s reefs have disappeared since the 1950s.
Coral reefs in the Gulf of Eilat in southern Israel are expected to continue to thrive in warmer waters for some time, for evolutionary reasons. According to Professor Maoz Fine, a coral expert at the Eilat Inter-University Institute of Marine Sciences and the Hebrew University of Jerusalem, Eilat’s corals spent 6,000 years moving from the Indian Ocean in passing through the Bab el-Mandeb Strait, between Djibouti and Yemen. Only corals capable of supporting the warm water of this strait could pass through and travel to the northern Red Sea and the Gulf of Eilat.
This theory was called into question earlier this month with the first reports of coral bleaching off the coast of Eilat.
A bleaching coral in the Gulf of Eilat earlier this year, in an undated photo. (Credit: Omri Omessi/Assaf Zvuloni, Israel Nature and Parks Authority)
According to experts, including Fine, who wrote in the Israeli academic journal Ecology and Environmentthis phenomenon follows an unprecedented increase in sea water temperature.
When water temperatures exceed a critical threshold, corals expel algae and their white skeleton becomes visible, hence the term “bleaching”. If conditions don’t recover quickly, the corals will eventually starve.
