Hawaiian Triggerfish on Ningaloo Reef
Hawaiian Triggerfish on Ningaloo Reef

Coral Catastrophe on Ningaloo Reef

An ecological disaster

Furthermore, the abundance of healthy coral colonies experienced a sharp decline from 3,452 individuals in 2018 to just 153 in 2022. The abundance of coral genera also took a significant hit, falling by 84.61% from 26 genera in 2018 to just four in 2022. Dominant genera such as Acropora, Montipora and Echinopora were eradicated from the study sites.

Rice Corals (Montipora capitata), Kane'ohe Bay, O'ahu, Hawaii

Coral resilience under climate stress: Insights from Hawaiian reefs

In 2015, amidst a marine heatwave, Barott’s team tagged numerous coral colonies, initiating a study on coral adaptability. Their focus: the rice coral (Montipora capitata) and finger coral (Porites compressa), two dominant species in the region. Over the years, multiple heatwaves provided a unique opportunity to observe coral responses, revealing both resilience and vulnerability.

Mariah Opalek, at the water tanks where the research was conducted.

Coral growth depends on type of symbiotic algae they associate with

Scientists discover a surprising tradeoff in coral growth linked to the symbiotic algae they host. The research sheds light on the delicate balance that corals strike in adapting to rising ocean temperatures.

Corals derive much of their energy from the algae living within their soft tissue, and it appears that some symbiotic algae species help corals withstand warmer water better than others.

Some of the coral bleaching that took place more than 90 metres before the ocean surface, in the Central Indian Ocean.

Ocean temperature rise caused coral bleaching at depths over 90m

In November 2019, researchers from University of Plymouth recorded unexpected evidence of coral bleaching more than 90 metres below the ocean surface. 

Describing their discovery as a "huge surprise," Dr Phil Hosegood, Associate Professor in Physical Oceanography at the University of Plymouth and lead on the project, said: "Deeper corals had always been thought of as being resilient to ocean warming, because the waters they inhabit are cooler than at the surface and were believed to remain relatively stable."

A variety of Acropora corals at Lighthouse Reef in Palau where researchers from CSIRO, UQ and PICRC saw rapid coral recovery with the release of dormant coral “seed banks” after a super typhoon in 2012.

Corals store dormant 'seed banks' like forests do

Initially slow, the recovery puzzled scientists in the study, led by marine ecologist Dr Christopher Doropoulos and research co-lead Dr George Roff, together with team members from the University of Queensland and Palau International Coral Reef Center, who expected regeneration to follow traditional patterns, driven by coral spawning events. These events involve the synchronized release of eggs and sperm into the water, leading to the dispersal of coral larvae that settle onto impacted reefs.

Corals in Palau did not suffer mass bleaching during the 2017 marine heatwave despite levels of heat stress and light intensity that were broadly equivalent to the conditions that led to mass bleaching in 1998 and 2010 at the same reefs.

Pacific coral reef shows increase in climate resistance

The ability of coral reefs to adapt to changing ocean temperatures is a pressing question in marine biology.  

Coral reefs are currently experiencing significant declines. These declines are primarily due to marine heatwaves, which lead to widespread coral bleaching and mortality. Understanding how coral communities can adapt to increasingly severe and frequent marine heatwaves is crucial for their survival in the face of climate change.

Photo shows a coral reef with a background of the sun's rays shining into the waters
The Coral Reef Breakthrough seeks to protect at least 125,000 square kilometres of shallow-water tropical coral reefs.

Coral Reef Breakthrough: An initiative to safeguard world's coral reefs

Coral reefs are essential for marine biodiversity and climate resilience, supporting at least a quarter of marine species and offering ecosystem services worth up to US$9.9 trillion annually. More than a billion people, including vulnerable coastal communities, depend on them for their livelihoods.

Today, these vital ecosystems are under threat due to the climate crisis and human activities, and time is running out to protect them.

Over the course of decades, polluted and warmer waters have bleached and killed up to 95% of Florida's corals.

Florida's Coral Reefs Under Siege from Rising Temperatures

Florida's coral reefs, a vital marine ecosystem, have been under severe threat due to extreme ocean temperatures this summer. The coral reefs, besides being biodiversity hotspots, also serve as a protective barrier against coastal erosion and are a significant source of revenue through tourism.

Efforts to protect and restore these reefs have been ongoing for decades. Coral restoration, which involves planting coral fragments, has been a primary method employed by scientists.

Health profiles of the elkhorn coral greatly differed among five examined areas, but the coral samples in the Dry Tortugas thrived compared to all the other sites

Endangered corals show encouraging resilience

In the face of daunting challenges to our planet's coral reefs, a glimmer of hope emerges from Florida's coastal waters.

Scientists from Ohio State University discovered that the endangered elkhorn coral population in the Dry Tortugas National Park in Florida were highly resilient in its ability to adapt and thrive, despite adverse factors like climate change, pollution and disease outbreaks.