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How do coral reefs survive climate change?

How do coral reefs survive climate change?

Status: 07/08/2023 06:12 AM

A third of the world’s population of coral reefs has already been destroyed. The researchers have now collected data for a two-year expedition. Show what makes some coral reefs more resilient to climate change.

The French exploration vessel “Tara” has been sailing in the Pacific Ocean for more than two years. Researchers on the ship stopped at nearly 100 coral reefs to take thousands of water and coral samples. The expedition ended nearly five years ago. Now become the first Data analysis results published.

The findings should help better understand the living conditions of corals, check their state of health and open up new possibilities for nature conservation. Coral reefs are among the ecosystems most threatened by climate change.

The research vessel Tara has been sailing around the world for years collecting data for research.

huge Corals die feared

According to one source, more than half of the world’s coral population is currently classified as vulnerable Report of the Intergovernmental Panel on Climate Change (IPCC). Marine biologist Christian Voelstra fears that without preventive measures, 99 percent of coral reefs could be extinct by the end of the century. Constance University. He was on Tara for 80 days and noticed increasing coral bleaching.

In order to be able to better protect coral reefs in the future, the researchers conducted the most comprehensive inventory yet. More than 5,000 species of corals are currently known worldwide. Each species has individually adapted to its environment and not all species suffer equally from climate change.

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Why are temperature changes so dangerous for coral reefs?

Coral color is a good indicator of coral health: healthy corals are colored by local biodiversity – especially by tiny algae that live in symbiosis with the corals. In doing so, they release vital nutrients for the corals.

The increase in water temperature due to climate change changes the metabolism of algae: instead of oxygen and sugar, they emit harmful oxygen radicals. To protect themselves, corals repel algae and bleach as a result. If temperatures remain high for too long, corals will starve.

Different Adaptability

Researchers have now discovered that one of the indicators of coral longevity and stress resistance is the length of their telomeres. These are the ends of the chromosomes that protect the genetic material. According to the results, corals that change telomere length depending on water temperature are short-lived and more sensitive to stress. On the other hand, long-lived, stress-resistant corals appear to have a mechanism for maintaining telomere length.

Telomere length is therefore a good measure for assessing coral health and coral biodiversity in order to evaluate reef restoration measures, according to the researchers.

Underestimating the importance of bacterial diversity in coral reefs

The species diversity of corals also helps assess the sensitivity of corals to environmental changes. The first results of the expedition were surprising: Bacterial diversity in coral reefs higher than previously thought.

According to Volstra, bacteria are relatively easy to study. So it acts as a good indicator of coral health. For example, the type and number of bacteria present in corals can be used to monitor the impact of climate change on coral reefs, so that action can be taken quickly in the event of a decline.

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Because not every coral reacts the same way to external influences. For example, some corals can evolve genetically through exchanges with bacteria. Such corals could adapt to climate change more quickly, says marine biologist Voolstra.

Stress resistance Thanks to the duplicate genes

On some reefs there were other reefs A survival feature in the genomeTwice there, researchers found specific genes primarily associated with the immune system and disease resistance. They hypothesize that such corals may be more resilient.

This could explain, for example, why corals survive in shallow waters for thousands of years despite being exposed to UV rays all year round. According to Volstra, a person may develop skin cancer with such radiation exposure.

“It will get worse before it gets better.”

The extensive research of the Tara mission shows that many corals are already sensitive to small changes in temperature. But more has also been learned about the mechanisms that make some coral species more resilient. So the marine biologist Volstra suspected a conversation with SWRThat even though temperatures are rising, there will always be coral reefs that can survive that need protection.

These resistant corals can serve as a reservoir from which the corals can recover at a later date.