These corals could hold the key to saving our reefs

  • elocal magazine By elocal magazine
  • Jul 2, 2024

The world’s coral reefs are facing unprecedented threats from climate change. According to the National Oceanic and Atmospheric Administration and International Coral Reef Initiative, coral reefs around the world are experiencing mass coral bleaching for the fourth time.

From February 2023 to April 2024, significant coral bleaching occurred in at least 53 countries. In 2022, bleaching affected 90 percent of coral reefs assessed at Australia’s Great Barrier Reef, one of the world’s largest coral reef ecosystems. Despite bleaching events and rising sea temperatures causing widespread decline, a glimmer of hope emerges from an unexpected source — the remote Kimberley coast of Western Australia.

The Kimberley region is known for its landscapes, gorges and waterfalls. These reefs located along the vast 12,000km Kimberley coastline contain a hidden treasure: a network of pristine intertidal reefs, teeming with life including dugongs, sharks, stingrays and seabirds. While surveying the Kimberley reefs at low tide, it is common to find turtles resting in gaps among the coral or in shallow reef pools waiting for the tide to return. Photo: Zoe Richards, Curtin University

It is home to the Montgomery Reef, the world’s largest inshore reef with a total area of 400 square kilometres, which rises from the ocean floor at low tide, creating cascading waterfalls and revealing a vibrant underwater ecosystem. Coral cover at the Kimberley region averages about 23 percent, similar to what is recorded on the Great Barrier Reef.

More than 225 species of coral have been documented — other intertidal reefs around the world usually have just a handful. Montgomery Reef rises from the ocean floor at low tide, creating cascading waterfalls.

Taxonomic studies have revealed many species recorded in the Kimberley are known only from Indonesia and they do not occur anywhere else in Australia, hinting that the corals that now live in northwest Australia may be closely related to corals in Indonesia, although this remains to be tested with population genetic studies.

What is most remarkable about these corals is their resilience.Unlike reefs elsewhere, Kimberley corals thrive under harsh conditions. The reefs endure hours of exposure at low tide to scorching sun and intense UV light. Even a major global mass bleaching in 2016 failed to trigger mass mortality, while neighbouring reefs suffered devastating losses.

Scientists believe the answer lies in the corals’ unique genetic makeup. Recent studies have identified genes in Kimberley corals that are under evolutionary pressure, suggesting an adaptation process. These naturally resilient corals may hold the key to understanding how coral reefs can survive a changing climate.

An examination of the whole genomes of Kimberley corals has found genes under recent selective pressure providing evidence that the corals are actively evolving in response to changes in the environment. While the exact function of these genes is not known, it is likely their increased prevalence helps corals survive extreme environmental conditions.

Researchers discovered that less tolerant corals have historically been eliminated from the Kimberley coast, resulting in a collection of locally adapted corals with the genetic make-up to withstand current climate stress. Further research is required to understand how Kimberley corals have developed higher thermal thresholds. However, these corals offer significant opportunities to enhance our knowledge of coral adaptation. Despite their potential, the vast diversity of naturally thermally tolerant Kimberley corals has been largely overlooked in the coral adaptation narrative.

These corals serve as a natural laboratory to study how diverse corals have adapted to climate change and to uncover the nature of these beneficial adaptations. Integrating Kimberley corals into the broader coral adaptation discourse is essential, as they offer evidence that corals can adapt to environmental pressures.

Associate Professor Zoe Richards is a coral taxonomist at Curtin University, Australia whose research revolves around coral biodiversity and how best to monitor and protect it. Working in the areas of systematics, phylogenetics, population genetics, ecology and conservation biology, she has conducted research on coral reefs across the globe for over 25 years. She is also curator of marine invertebrate zoology at the Western Australian Museum.