What is bleaching in the Great Barrier Reef?

When corals are under stress, they expel the microscopic algae that live in their tissues. Without these algae, corals' tissues become transparent, exposing their white skeleton. This is called coral bleaching. Bleached corals are not dead, but are more at risk of starvation and disease.

What is coral bleaching and why is it bad?

Coral bleaching occurs when corals are stressed by changes in environmental conditions such as temperature, light or nutrients. The coral expels the symbiotic algae living in its tissue, causing the tissue to turn white or pale.

What caused the Great Barrier Reef bleaching?

The leading cause of coral bleaching is climate change. A warming planet means a warming ocean, and a change in water temperature—as little as 2 degrees Fahrenheit—can cause coral to drive out algae. Coral may bleach for other reasons, like extremely low tides, pollution, or too much sunlight.

What is coral bleaching doing to the Great Barrier Reef?

Coral bleaching in the Great Barrier Reef

Well, in the past 20 years, over 90% of coral in the Great Barrier Reef has been bleached at least once. If this pattern continues, corals will not have enough time to fully recover and will quickly all starve to death.

What is coral bleaching?

Warmer water temperatures can result in coral bleaching. When water is too warm, corals will expel the algae (zooxanthellae) living in their tissues causing the coral to turn completely white. This is called coral bleaching.

Coral bleaching leaves Great Barrier Reef under threat

Where does coral bleaching occur in the Great Barrier Reef?

Severe coral bleaching affected the central third of the Great Barrier Reef in early 2017 associated with unusually warm sea surface temperatures and accumulated heat stress. This back-to-back (2016 and 2017) mass bleaching was unprecedented and collectively affected two thirds of the Great Barrier Reef.

When did the Great Barrier Reef start bleaching?

The Great Barrier Reef has experienced two major bleaching events in recent decades, in the summers of 1998 and 2002 when, respectively, 42% and 54% of reefs were affected by bleaching.

Why is coral bleaching important?

Coral bleaching occurs when corals are stressed by a change in environmental conditions. They react by expelling the symbiotic algae that live in their tissues and then turn completely white. The symbiotic algae, called zooxanthellae, are photosynthetic and provide their host coral with food in return for protection.

How much does the Great Barrier Reef affect bleaching?

Aerial surveys detected catastrophic coral bleaching on around 60 percent of the reef's corals, reports Darryl Fears for the Washington Post. The Great Barrier Reef is the largest coral reef system in the world, stretching for 1,429 miles over an area of approximately 133,000 square miles.

How much has coral bleaching affected the Great Barrier Reef?

Coral bleaching has affected 98 percent of Australia's Great Barrier Reef since 1998, leaving just a fraction of the world's largest reef system untouched, according to a study published Friday.

How does coral bleaching affect humans?

In many places, the loss of coral reefs would amount to an economic disaster, depriving fishermen of their main source of income, forcing people to find more expensive forms of protein and undermining the tourism industry.

Why is coral bleaching a problem in Australia?

Overfishing. Coral bleaching is the result of global warming caused by the mining and burning of fossil fuels like coal. Global warming is heating our oceans, and if the water stays too hot for too long, corals bleach and die. Farm pollution is one of the key drivers of the Reef's decline.

Where does coral bleaching happen?

Iconic reefs such as the Great Barrier Reef in Australia and the Northwestern Hawaiian Islands in the United States have all experienced their worst bleaching on record with devastating effects. The bleaching of the Great Barrier Reef in 2016 and 2017, for instance, killed around 50% of its corals.

How does coral bleaching affect climate change?

Climate change leads to: A warming ocean: causes thermal stress that contributes to coral bleaching and infectious disease. Sea level rise: may lead to increases in sedimentation for reefs located near land-based sources of sediment. Sedimentation runoff can lead to the smothering of coral.

Is coral bleaching natural?

Coral bleaching is a stress response and individual coral colonies will suffer from a degree of bleaching in any given summer. This is a natural process and not of particular concern.

How much of the Great Barrier Reef is bleached 2020?

Half of the coral in the Great Barrier Reef is gone (2020)

(CNN) Warming waters from escalating climate change have caused coral bleaching in 91% of reefs surveyed along the Great Barrier Reef this year, according to new findings from an Australian government agency.

How can we prevent coral bleaching in the Great Barrier Reef?

Use environmentally-friendly cleaners and fertilisers. Keep gutters, sinks and drains free of chemicals and rubbish as what washes down sinks and drains could end up on the Reef. Minimise water runoff by planting trees, garden beds and ground cover around your home. Use re-useable shopping bags rather than plastic bags.

How does coral bleaching affect biodiversity?

Bleaching leaves corals vulnerable to disease, stunts their growth, affects their reproduction, and can impact other species that depend on the coral communities. Severe bleaching kills them.

How do we stop coral bleaching?

Can bleached coral come back to life?

Warmer waters can trigger a coral bleaching where the coral turns white as it expels the symbiotic food-producing algae living in its tissues. Prolonged bleaching events often cause corals to die from starvation, but they can recover if they reclaim their food source within a few weeks.

Why is the barrier reef dying?

How is the Great Barrier Reef dying? The Great Barrier Reef has suffered severe harm at the hands of humans. Toxic coastal pollution, overfishing and unsustainable tourism all contribute to the damage done. However, the biggest threat of all is climate change, which causes coral bleaching and ocean acidification.

What is killing the coral reefs?

Coral reefs face many threats from local sources, including: Physical damage or destruction from coastal development, dredging, quarrying, destructive fishing practices and gear, boat anchors and groundings, and recreational misuse (touching or removing corals).

What are the 3 main threats to the Great Barrier Reef?

What happens if the Great Barrier Reef dies?

If coral reefs disappeared, essential food, shelter and spawning grounds for fish and other marine organisms would cease to exist, and biodiversity would greatly suffer as a consequence. Marine food-webs would be altered, and many economically important species would disappear.

Is the Great Barrier Reef dead?

In 2020, a study found that the Great Barrier Reef has lost more than half of its corals since 1995 due to warmer seas driven by climate change. As global warming continues, corals will not be able to keep up with increasing ocean temperatures.