Technology large parts of the Great Barrier Reef are again...

large parts of the Great Barrier Reef are again fading en masse

It is the third time in just five years that the reef has been hit severely.

The beautiful Great Barrier Reef is the largest coral reef in the world. Many divers have already marveled at the splendor of this reef. But as you probably haven’t noticed, the reef has been in heavy weather for a long time. The reef is mainly ravaged by periods of extreme bleaching. Now researchers are sounding the alarm again. Because the reef is not even over the previous period of mass bleaching, or the next wave has already surfaced. And the severely affected part has never been as big in recent years as it is now.

More about bleaching
Coral lives in symbiosis with microscopic algae that provide the coral with food and color. When the coral has to deal with stress (due to higher water temperatures or pollution), the algae leave the tissue of the coral. As a result, the coral loses not only an important source of food, but also color. The coral weakens and becomes more susceptible to disease. One of the biggest stresses that the coral is currently facing is the warming of the seawater. Bleaching has therefore become a rapidly occurring problem.

The Great Barrier Reef was particularly hard to bleach in 2016 and 2017. When that happens, researchers also speak of one “Mass bleaching event”. Either; “A period of time when many reefs stretched over a large area fade at the same time,” explains a spokesman for the Great Barrier Reef Marine Park Authority On Scientias.nl from. In 2016, heat waves caused a huge bleaching in the northern part of the Great Barrier Reef. In 2017 it was the turn of the middle part of the reef. More than a third of the coral in the northern and central parts is said to have died.

Affected areas of the Great Barrier Reef in 2016 and. 2017. Image: ARC Center of Excellence for Coral Reef Studies

Current situation
But now scientists are sounding the alarm again. Several aerial photos reveal that large parts of the reef are fading again. This is currently taking place on an unprecedented scale. “For the first time, we have noticed severely bleached reefs in both the northern, central and southern parts of the Great Barrier Reef,” the spokesperson said. “The most bleached areas are generally more on coastal reefs than on the open sea.” It is not surprising that large parts of the reef are now bleaching, given the situation in Australia. Last year, for example, the country faced an immensely hot summer in which record-breaking temperatures were tapped. “The current bleaching period is very much in keeping with this hot summer.”

Affected areas of the Great Barrier Reef by 2020. Image: ARC Center of Excellence for Coral Reef Studies

The numbers
The Great Barrier Reef extends over an area of ​​344,000 square kilometers. That is larger than the United Kingdom, Switzerland and the Netherlands combined. During the aerial survey, scientists sighted 1,036 reefs and studied the corals found in shallow water – that is, to a depth of five meters. This analysis shows that about 25 percent of the reefs have been seriously bleached. This means that on each reef, more than 60 percent of the corals are heavily affected. In addition, 35 percent has faded moderately and 40 percent has suffered little to no damage. And the latter is of course still somewhat hopeful news.

Extreme bleaching
Scientists are very concerned. Because this is already the third time in just five years that the reef has suffered a period of extreme bleaching. The fact that these periods now follow each other closer to each other has everything to do with the warming earth. “Climate change remains the biggest threat to the reef,” said the spokesman for the Great Barrier Reef Marine Park Authority. “As the Earth warms, the ocean will absorb about 90 percent of that extra heat. As a result, the average temperature of the ocean is rising and heat waves are increasingly being generated. This means that periods of extreme bleaching are increasingly on the scene. ” What is particularly striking about the current bleaching wave is how scattered the severely affected areas are. “In 2016 and 2017, the affected areas were more limited,” said the spokesperson. “Now we see that it is much more widespread. However, this does not immediately mean that more reefs have now faded. ”

Faded coral near Magnetic Island in Australia. Image: Klara Lindström

It is important to note that faded coral does not immediately mean dead coral. Light or moderately bleached reefs are likely to recover and survive. Although that becomes increasingly difficult if the coral is not given the opportunity to patch itself up again. It is therefore bad news that periods of extreme bleaching now follow each other more quickly. Because it means that the reef has not even recovered from one blow before it has to endure the next. And if the reef has to absorb one impact after another, the question is to what extent the coral can recover in that case. “Some corals that were affected in 2016 and 2017 are again severely faded. But other reefs have only been hit for the first time. It is important that there are still areas that have not faded at all. The pattern and the accumulating effects of bleaching therefore remains very complicated to map. ”

Inventive solutions
To save the coral from destruction, several scientists have already come up with inventive solutions. For example, an American professor already suggested pumping cold water at the bottom of the ocean to the reef so that the water temperature drops. Or how about a project by Australian researchers who hauled millions of coral larvae to damaged areas? Scientists also decided to place loudspeakers on severely damaged coral reefs, so that fish return to these stagnant places. It is a selection from a range of possibilities that scientists play with. But whether it really makes a difference… “Research is constantly being conducted into the possibilities of helping corals and making them more resistant to the effects of climate change,” the spokesperson explains when asked. “This certainly produces promising results in the laboratory and on a small scale in the reef itself. However, solutions are not yet widely deployed at this time. The most important and fastest method to secure corals is still a global effort to reduce greenhouse gas emissions. ”

To rescue
However, the question is whether we can still save the beautiful Great Barrier Reef. Because it is expected that bleaching will increase in the future. Some studies even state that by 2070 the majority of all coral worldwide has faded. And that is quite sad, especially since the reef has also faced hot fires in the past. “The reef has changed dramatically in the past 30,000 years. Mainly due to rising and falling sea levels. These changes were part of the natural variation. However, the current situation is completely different from the geological changes of the past. The current changes are man-made and happen faster than the natural geological changes of the time. Although the reef is still a very resilient ecosystem and can still show signs of some recovery, the earth has only warmed up about a degree compared to the pre-industrial level. However, we are expected to head for a temperature rise of about three degrees or more by the end of the century. And that is a scenario in which corals can no longer recover. ”

So the most important thing is that we avert this extreme rise in temperature in any case. And we can only do that if we do our best to achieve the objectives of the Paris climate agreement. “The measures we are taking now will matter,” said the spokesperson. “We want people to think globally and act locally. Because every effort, no matter how small, is of collective importance. If we can achieve this and have strong local protection measures in place, we can still protect coral reefs, including the Great Barrier Reef. ”

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