Thin sunscreen layer to *save reef from bleaching* for first time in twenty million years

Scientists are suggesting that a thin layer of floating calcium carbonate can cut sunlight over reefs by 30% and save some high value reefs from bleaching.

This should work well on all the reefs that evolved in the last fifty years and which don’t have moving water.

But half of the coral genera around today have been around since the Oligocene (23-34 million years ago) and for most of that time the oceans were warmer. (Lucky human civilization evolved just in time to save all these reefs from extinction.)

Bleaching has probably been going on for millions of years longer than we have been scuba diving with cameras to film it. We only discovered coral bleaching in the 1980s. Not surprisingly, marine life has ways to adapt to heatwaves by chucking out the symbionts that don’t thrive in higher temperatures and replacing them with new inhabitants that do.

Yes, let’s cover our most diverse and important reef systems with an artificial layer that cuts incoming sunlight by a third — What could possibly go wrong?

Scientists from the Australian Institute of Marine Biology say tests of a floating “sun shield” made of calcium carbonate show it could protect the reef from the effects of bleaching.

“It’s designed to sit on the surface of the water above the corals, rather than directly on the corals, to provide an effective barrier against the sun,” Great Barrier Reef Foundation managing director Anna Marsden said.

The trials, headed by the scientist who developed the country’s polymer bank notes, on seven different coral types found that the protective layer decreased bleaching of most species, cutting off sunlight by up to 30%.

Marsden said it was impractical to suggest that the “sun shield” – made from the same material found in coral skeletons – could cover the entire 348,000 square-kilometre reef.

“But it could be deployed on a smaller, local level to protect high value or high-risk areas of reef,” she added.

It’s not like the whole ocean is at one temperature and one constant pH

There is and always has been constant turbulence in the oceans and marine life is used to it. Ocean acidification happens every day in some places — no biggie. There is a large daily swing after sunset in pH over many reefs. Far from that being a problem, fish seem to behave better when artificial tanks mimic these natural swings. Indeed a bit less alkalinity is better for hundreds of species. Some coral reefs thrive in a more acidic ocean, and we appear to have a pretty big safety margin: farmed fish seem to cope fine with CO2 levels that are even fifty times higher than today.

The story of life on Earth is that everything keeps shifting and biology adapts. In one situation, when trapped, salt water fish evolved to become freshwater fish in just fifty years*. In private, NOAA experts will admit they can’t name one single place that is affected by ocean acidification.

While some estimates said 90% of the Great Barrier Reef was bleached recently, other studies said it was more like 5%. Even the head of the Great Barrier Reef Marine Park Authority has said that activists are distorting and exaggerating the threats. The Great Barrier Reef is recovering faster than scientists expected. Possibly because it is 3,000 kilometers long and has over a hundred tough spots that survive and replenish the rest.

Other ideas to save the reef include putting shade cloth over the Great Barrier Reef to save it from climate change or using giant fans to stop bleaching.

Coral reefs first became widespread about 200 million years ago. It takes some kind of delusional hubris to think they suddenly can’t survive without human help, or that we have any idea what we are doing messing with a complex well developed system.

Of course, if you work at an Australian university and say that, you too could face misconduct charges, like Peter Ridd.

Image: Wikimedia, author Wise Hok Wai Lum: Flynn Reef 2014.

*Error corrected. This originally said “six astomishing months” but should have said “fifty years”, which on evolutionary time frames is still incredibly fast.

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