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Great Barrier Reef endures third mass bleaching event in five years

Friday, April 3rd 2020, 12:34 pm - Conservation projects have seen successes when innovative strategies are implemented in areas that are trying to protect their coral reefs.

Scientists that are monitoring the Great Barrier Reef in Australia report that it has suffered its third mass bleaching event in five years. The reef is considered to be the largest living structure in the world, but warming temperatures are straining the corals and are causing these bleaching events to become increasingly common.

A study that was published in April 2018 found that half of the Great Barrier Reef had died since 2016 when this region of the world experienced abnormally warm temperatures. The El Niño and La Niña weather patterns contributed to the extreme conditions, however, neither event was occurring when this year’s mass bleaching took place.

bleached coral reef wiki cc Bleached branching coral (foreground) and normal branching coral (background). Keppel Islands in the Great Barrier Reef. Credit: Acropora/ Wikimedia Commons. CC BY-SA 3.0

Oceans cover over 70 per cent of the Earth’s surface and have the capacity to store more than 1,000 times the amount of heat than the atmosphere, which is why aquatic environments are particularly sensitive to the greenhouse gas emissions we release.

Corals start to bleach when the water becomes too hot and causes them to expel the colourful algae that live on them. The coral relies on the algae because it is their primary food source, while the coral provides the algae with a protected environment and nutrients needed for photosynthesis. The absence of the colourful algae leaves the coral with a stark white appearance.


The ecosystems within oceans are complex and can stretch over vast areas, making conservation efforts unique and specific for each region. While the frequency of mass bleachings is worrisome, the good news is that coral reefs can recover if temperatures return back to normal.

Marine experts face many decisions when choosing how to best protect coral reefs and have found that increased monitoring and involvement from local governments and communities have been key factors in successful coral reef conservation projects.

See below for a look at the inspiring work that organizations are doing to conserve coral reefs across the world.

USAID Project REGENERATE, Maldives

The Maldives is a low-lying atoll nation in the Indian Ocean and their economy largely relies on coral reefs for their tourism and fishing industries. Despite experiencing mass bleachings in 1998, 2010, and 2016, the IUCN says that these coral reefs have shown a “great capacity for resilience.”

Maldives coral wiki cc Coral reef in the Maldives. Credit: Tchami/ Wikimedia Commons. CC BY 2.0

Project REGENERATE is funded by the United States Agency for International Development (USAID) and helps local governments and researchers access science and technology and use education and monitoring while providing sustainable financing mechanisms to support resilient marine management.

Southern Leyte Coral Reef Conservation Project (LRCP), Philippines

Coral reefs located in the Southern Leyte province in the Philippines host some of the most biodiverse marine habitats in the world, but face many stressors including abnormally warm temperatures and pollution.

philippines coral reef wiki cc A shark swimming through Tubbataha Reefs Natural Park, which is a protected area of the Philippines in the middle of the Sulu Sea. Credit: Nikswieweg/ Wikimedia Commons. CC BY-SA 3.0

Since 2002 the LRCP has worked with local stakeholders and researchers to increase data collection. The organization’s website says that learning more about the reefs will indicate how protected areas improve biodiversity and handle stressors that cannot be controlled, such as atmospheric temperatures.

North Bali Reef Conservation, Bali - Indonesia

Tianyar is a small fishing village on the northeastern coast of Bali and community work there is slowly repairing the damage that coral reefs have sustained over the past century. The North Bali Reef Conservation’s website says in the early 1900s coral was harvested and crushed into a fine white powder that would be painted onto homes of the wealthy. Pollution and disruption from the fishing industry have added further stress to reefs that were previously harvested or damaged by anchors dropped by visiting boats.

coral reef indonesia wiki cc Coral reef in Indonesia. Credit: Nick Hobgood/ Wikimedia Commons. CC BY-SA 3.0

Some of the successful initiatives that the organization has created include a community recycling centre and the installation of over 3,000 artificial reefs that expand the habitat for many aquatic species.

Reef Rescuers, Seychelles

A mass bleaching event in 1998 killed up to 90 per cent of the coral reefs in some areas in Seychelles due to unusually warm temperatures. The reefs suffered another bleaching event in 2016, but by this point, the Reef Rescuers project was already underway.

seychelles wiki cc Anse Source d'Argent, Seychelles. Credit: dronepicr/ Wikimedia Commons. CC BY 2.0

The project launched in 2010 and their website states that they were the world’s first large-scale coral reef restoration project. Their “coral gardening” technique involves collecting coral fragments from healthy sites, growing these fragments in underwater nurseries to maturity, and then replanting them into degraded reefs. They have successfully transplanted over 24,000 corals and have welcomed dozens of scientific divers from around the world to study their successful restoration techniques.

RangerBot, Great Barrier Reef, Australia

The Great Barrier Reef foundation designed the Rangerbot, which is the “world’s first autonomous underwater drone” that is dedicated to protecting coral reefs. This unique machine was designed to meet the foundation’s most pressing needs and is able to map expansive underwater areas, monitor coral bleaching indicators and water quality, and control pests like the Crown-Of-Thorns Starfish.

starfish wiki cc The Crown-Of-Thorns Starfish resembles the biblical crown of thorns and is one of the largest starfish in the world. Credit: Matt Wright/ Wikimedia Commons. CC BY 2.5

In addition to the stress from warming temperatures, booming populations of Crown-Of-Thorns Starfish are challenging the Great Barrier Reef. These coral-eating starfish are not an invasive species but have been responsible for destroying significant amounts of coral reef. RangerBot is able to control the pests’ population by locating the starfish with SONAR and multiple cameras. The Crown-Of-Thorns are subsequently killed with a lethal injection from RangerBot.

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