Great Barrier Reef: Deeper Regions Show Potential Resistance to Rising Ocean Temperatures

Rising sea temperatures have caused widespread coral bleaching and death, jeopardizing the entire ecosystem of Great Barrier Reef.

Scientists have primarily focused on the effects of warming surface waters on coral health, but a new study published in PNAS offers a glimmer of hope for the future of the Great Barrier Reef.

This article explores the possibility that deeper, cooler waters may serve as refuges for heat-stressed corals and examines the potential role of ocean stratification in protecting these deeper reefs.

Climate change and the Great Barrier Reef

The Great Barrier Reef, the world's largest coral reef system stretching over 2,300 kilometers (1,400 miles) along the coast of Australia, has been sounding the alarm for years.

Vibrant coral colonies, once teeming with life, have bleached and died due to rising sea temperatures, a direct consequence of climate change.

These rising temperatures disrupt the symbiotic relationship between coral and algae, leaving the coral vulnerable to disease and starvation.

Climate change models have traditionally focused on surface water temperatures, which have a direct impact on coral health.

However, a new study published in the Proceedings of the National Academy of Sciences (PNAS) suggests that there may be a glimmer of hope for these underwater wonders.

Also Read:Great Barrier Reef: Flood Plumes, Heavy Waves Due To Cyclones Could Have Damaged Coral Reef System

A cool refuge for stressed corals

The study, led by researchers from the ARC Centre of Excellence for Coral Reef Studies, investigated the potential for mesophotic reefs to act as refuges for corals facing thermal stress.

Mesophotic reefs are coral reefs located at depths ranging from 30 to 150 meters below the surface. These deeper waters tend to be cooler and more stable than the shallow waters where most coral reefs are found.

The cooler temperatures at these depths could provide a vital refuge for corals that are struggling to survive in the warming shallows.

Ocean stratification, which refers to the layering of water with different temperature and density levels, may also play a role in protecting these deeper reefs. By acting as a barrier, stratification can prevent warm surface waters from mixing with the cooler waters below. This creates a haven for temperature-sensitive marine life.

The researchers used a downscaling method to predict bottom temperature changes under various climate change scenarios.

Their findings suggest that while thermal stratification may offer some protection for mesophotic reefs, it is not a foolproof solution.

If greenhouse gas emissions continue to rise unabated, even the cooler deeper waters may eventually be affected by warming.

The study predicts that mesophotic coral reefs, located at depths of 30-50 meters, will experience temperature increases of 0.5-1°C by 2050-2060 under low emissions scenarios, and 1.2-1.7°C under high emissions scenarios.

While some shallow water coral species may not be able to survive the move to deeper waters due to different light or pressure requirements, the existence of these cooler mesophotic zones offers a glimmer of hope for the future of coral reefs.

Further research is needed to determine the specific types of corals that could thrive in these deeper environments and to develop methods to assist coral relocation efforts.

The study's findings offer a valuable new perspective on the impacts of climate change on coral reefs. While the potential for mesophotic reefs to act as refuges is promising, it highlights the urgent need to address climate change and mitigate its effects on our oceans.

Finding ways to reduce our carbon footprint and curb rising global temperatures is critical for the survival of these vital ecosystems and the countless marine species that depend on them.