The perfect match of nature breaks down and the Great Barrier Reef is in danger


August 20, 2018 05:13:28

Pull the veneer off and nature is a swarming war zone of many fires. Species compete with their own species and others for limited resources. In a world of dog-eaters built on Darwinian principles and food chain hierarchies, only the most fit survive – and the winners take it all.

But there are oases of harmony, where evolution has played matchmaker and has made summaries of peaceful coexistence. Take, for example, a relationship formed over 210 million years ago around the time when dinosaurs first appeared on Earth.

Until recently, this remarkable and visually brilliant partnership was still gangbusters.

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This is a close-up of a healthy coral coral – a relative of both jellyfish and anemones.

The small creature, which can be as small as a mill imetre in diameter, forms the basis of coral reefs all over the world.

But it does not do it alone – it gets a little help from microscopic algae known as zooxanthellae

Like their land-based plant families, zooxanthellae performs photosynthesis – a process that converts sunlight, water, and carbon dioxide into by-products, including oxygen and glucose.

Not only do the algae provide the coral with vibrant colors, but about 90 percent of what they produce has passed to the host.The coral polyps in turn separate the calcium that forms the rigid structure of a coral reef colony.

"The most important thing about corals is that they make their own place. wen to live. Nothing else does that ", said head scientist at the Australian Institute of Marine Sciences, Charlie Veron – a man who is called" the godfather of coral. "

And in return, the algae can nestle in the small crevices of the coral and prevent them from becoming easy feed for the swarms of marine life coming together in a healthy reef environment.

Fueled by this harmonious relationship, the polyps, or clones, reproduce again and again.A perfect collaboration in a murky world of border anarchy

Over the course of tens of thousands of years these colonies spread to the impressive underwater riff structures we know today.

Nothing more spectacular than the Great Barrier Reef in Australia

"So corals have joined with algae to build things that nothing else on earth can match, they live and I think that is just as fascinating as biology can get, "z egg Mr. Veron, a septuagenarian who was diving in the waters around the Great Barrier Reef for half a century.

In order to place its size in perspective, the third largest coral reef in the world is the Florida reef that stretches for 270 kilometers south of Florida.

The third largest is the Belize Barrier Reef of more than 300 kilometers.

The Great Barrier Reef is more than 2,300 kilometers with an area of ​​almost 350,000 km2.

And size is important. Although coral reefs cover only 1 percent of the world's land mass and 2 percent of the ocean floors, they provide a home for almost a quarter of all marine life.

But the symbiotic relationship between coral and algae, which has survived since the late Triassic period, is breaking down.

Most reef-built corals require a "Goldilocks zone" to thrive. They can only thrive in an environment with water temperatures between 18 and 29 degrees Celsius. Places where sunlight can penetrate, where the water is salty and the sea is not too rough.

The delicate reef ecosystem is now being challenged by the same man-made factors that scientists say are responsible for climate change: rising temperatures and increasing levels of carbon dioxide in the atmosphere.

In 1998, the Great Barrier Reef experienced its most destructive bleaching event to date.

Algae, which respond to environmental changes, increased the production of oxygen to levels of toxic corals hosted. Eventually the coral started to drive out his roommate in an act of self-defense.

The corals of the half reef were damaged. The southern and central regions were the most affected.

Four years later it happened again.

The southern and central parts of the reef were hit hard again.

But then came 2016. A peak in water temperatures killed about a third of all shallow corals throughout the reef.

Half of the corals north of Port Douglas died in the space of eight months.

The event was so intense researchers said it was as if parts of the reef in the north were "boiled". [19659009] It was not over yet.

The following year another 20 percent of the corals were affected – the first back-to-back bleaching events ever recorded.

Belize Barrier Reef 300km

] ] <1 10/01 10-30 30-60 > 60 % bleached 1998

] [1 9460346] ] ] ​​ <1 10/01 ] 10-30 30-60 > 60 % Bleached 2002

<1 10/01 10-30 30 -60 > 60 % Bleached 2016 [19659043] ] ] [194612] 29] [19461[] ] ] [1 9461680] ]

Zooxanthallae algae

Port Douglas Cairns ] Townsville ] Queensland

Florida reef [19469041] 270km Great barrier reef 2300km Belize Barrier Reef 300km

An unprecedented succession of coral bleaching has left reefs around the world in a catatonic state. Almost half of the Great Barrier Reef has been reduced to a coral cemetery, with coral covering at the lowest point since monitoring began.

Under the right conditions, corals can regroup with algae and regrowth and this has happened in many parts of the reef. But even for the fastest growing corals that can last a decade.

"The problem with a 10-year window that is needed for a decent recovery is that the probability that we have a fifth bleaching event in that period is actually very high, because of the greenhouse effect," said director of the ARC Center for Excellence for Coral Studies at James Cook University, Terry Hughes.

"I feared it might be already next year."

While he can not predict when the next big bleach will happen, Professor Hughes is confident that the reef of the future will never look like old.

The heat-sensitive corals die in larger numbers than harder corals that are harder to bleach and better equipped to recover.

The reef is transforming – but to what extent this largely depends on how countries respond to climate change, according to Professor Hughes.

To get a better idea of ​​what the reef will look like in different scenarios of the greenhouse effect, the US National Oceanic and Atmospheric Administration science agency has created these models.

The map "emissions continue unabated" predicts when parts of the reef will experience two bleaching events in a decade, if nothing is done to reduce global carbon emissions.

This shows that by 2025 and 2030 many parts of the reef are bleaching, twice per decade, with almost the entire reef bleached in 2065.

The other map shows a scenario in which the emissions peak in 2040, but after decrease. By 2040, sections on the reef will experience bleaching events twice per decade, with more sections experiencing it in 2065 and 2085.

Hoewel Charlie Veron volhoudt dat hij een realist is, neigen zijn standpunten naar het pessimistische einde van het spectrum.

"Ik zie wat er voor me ligt en ik ben doodsbang, ik ben doodsbang voor mijn familie, mijn kinderen, en ik doe er alles aan om mijn gezin te beschermen tegen wat eraan komt," de marine wetenschapper zei.

M. Veron, die per ongeluk een koraalkenner werd nadat hij verliefd was geworden op de intensiteit van het leven dat hij onder water vond, is nu gestopt met zijn onderzoek naar koralen om een ​​fulltime, zelfbenoemde advocaat te worden.

Toen klimaatverandering voor het eerst werd voorgesteld in de jaren 1980, was de heer Veron zeer sceptisch, herinnerend aan zijn eerste blootstelling aan het polariserende debat over veranderende weerspatronen in de wereld.

Maar in plaats van het af te doen als bunkum, sprong Mr. Veron in de academische literatuur en bestudeerde de gegevens.

Zijn epiphany was zo plotseling als het was schokkend. "Oh mijn god, dit klopt", herinnert hij zich terwijl hij zich realiseerde wat de gevolgen waren van de toenemende kooldioxide-uitstoot.

Niet gecontroleerd, deze emissies zouden de chemie van de oceanen veranderen – de "longen van de aarde" – wegvagen koraalkolonies en het opwekken van een omgevingsketenreactie.

Het resultaat is een term die niemand licht zou moeten gebruiken: massale extinctie. Dat zou de zesde zijn op aarde in de afgelopen 500 miljoen jaar, maar de eerste sinds mensen arriveerden.

"In de mate waarin we gaan worden we een uitheemse soort op onze eigen planeet, omdat we gaan om al het andere te vernietigen. "

" Dat zal het einde van de mensheid zijn. "

M. Veron is geen klimaatwetenschapper en het is eerlijk om te zeggen dat zijn meningen niet universeel door zijn edelen worden goedgekeurd. Maar zijn overtuiging is absoluut.

Het scenario dat hij beschreef is niet hypothetisch, benadrukt hij. Er is voorrang. Wanneer oceaanhabitats in het verleden zijn ingestort, zijn ze "miljoenen jaren lang ingestort" gebleven.

Kijk 7.30 vanavond voor de eerste van drie speciale stukken over de staat van het rif van verslaggever Peter Greste en producent Amy Donaldson.


Onderzoek en interviews: Amy Donaldson en Peter Greste

Ontwikkeling: Ri Liu and Nathanael Scott

Design: Alex Palmer

Notes about this story








First posted

      August 20, 2018 05:00:51


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