Scientists develop ‘sun-shield’ that could save coral reefs
Charli Shield
March 28, 2018
As water temperatures rise and ocean acidity levels increase, corals are dying off at record rates. Now, researchers believe they may be able to prevent coral bleaching in parts of the world's largest coral reef system.
An ultra-fine ‘sun-shield’ created by Australian scientists could be used to protect the Great Barrier Reef from further coral bleaching.
By spraying a protective layer onto the surface of the water, researchers believe parts of the reef could be shielded from sunlight and effectively cooled.
"While it’s still early days, and the trials have been on a small scale, the testing shows the film reduced light by up to 30 percent," said Anna Marsden, from the Great Barrier Reef Foundation (GBRF) .
Created using calcium carbonate and 100 percent biodegradable, the film is some 50,000 times thinner than human hair, according to the GBRF.
"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," Marsden said.
A team of scientists, led by the pioneer of Australia’s polymer bank notes, tested the protective layer on several different types of coral and found the film decreased bleaching in most species.
Not an all-encompassing solution
Scientists believe the film has the potential to prevent further damage to the World Heritage-listed site, which has suffered significant bouts of coral bleaching caused by rising sea temperatures and increasing ocean acidity.
While the shield is not intended to be a solution for the entire reef, which stretches 348,000 square-kilometers, Marsden said it could be applied to smaller, high-risk areas.
“The concept needs more work and testing before it gets to that stage, but it’s an exciting development at a time when we need to explore all possible options to ensure we have a Great Barrier Reef for future generations," she said.
The site, which attracts millions of tourists each year, is the world's largest coral reef, home to some 400 types of coral, 1500 species of fish and 4000 varieties of molluscs.
Scientists have observed widespread bleaching across the reef since the 1990s, with the most significant bleaching events occuring in 2016 and 2017 and claiming an estimated two-thirds of the reef.
cs/ (AFP, GBRF)
Too hot for turtle guys: Great Barrier Reef is dangerously warm for male green sea turtles
Because of warming climates, green sea turtles at the Great Barrier Reef are having female babies almost exclusively. This could lead to the end of the entire species.
Image: Imago/Imagebroker/N. Probst
Single green females only?
In the largest green sea turtle colony, a lopsided majority of newborn babies are female. Male turtles hatch from just one percent of the eggs around the Great Barrier Reef. Researchers now fear for the survival of the species.
Image: picture alliance/dpa/Prisma/R. Mohammed
Too hot for guys
When sea turtles first lay their eggs, it's not initially clear whether male or female young ones will hatch. That's determined by the temperature of their surroundings. The hotter the sand, the higher the probability that babies will be female. From 29.9 degrees Celsius upward, there won't be little turtle boys. And because of global warming, this benchmark is exceeded more and more frequently.
Image: Imago/Nature Picture Library/Zankl
Male or female? Hard to tell
It's difficult to determine a sea turtle's sex. You can only tell for sure once the animal is fully grown - and that takes at least 20 years. That is probably why the surplus of females has gone unnoticed for so long. One way to tell the sexes apart: Male turtles have a longer tail and longer claws.
Image: Imago/imagebroker
Worrying numbers
Now, researchers from the US and Australia have developed a method to determine the sex of green sea turtles via DNA and blood tests while the animals are still young. What they didn't expect is that today already, 90 percent of green sea turtles at the Great Barrier Reef are female.
Image: Getty Images/M. Kolben
Sex is a rare treat
The small number of males is not the only challenge for green sea turtles. They are only sexually mature at 15, and even then, they only have sex every three years on average. Evolutionary speaking, a small female surplus in populations is nothing out of the ordinary. But the turtles cannot survive entirely without men.
Image: Imago/StockTrek Images
200 turtle babies in one nest
Female sea turtles return to the beach where they hatched to lay their own eggs again and again. On Raine Island's beach, the largest nesting ground for green sea turtles in the Pacific, you can find up to 18,000 animals during high season. After the eggs have been warmed by sun and sand long enough, the babies hatch, make their way into the sea and only return once it's their time to lay eggs.
Image: Imago/Zuma Press
Female surplus across the world?
Researchers believe there's a lack of male sea turtles across the world. That's why they're examining the effect that rising temperatures have had on green sea turtle populations along the coasts of Hawaii and on the island of Saipan in the western Pacific. The early gender detection method could lead to surprising results there as well.
Image: Imago/ZUMA Press
Dangerous heat
The results of the Australian study are bad news for other animals as well. Other reptiles, like crocodiles or lizards, also develop their sex due to temperature. With alligators, things work in exactly the opposite way as they do with sea turtles: If it gets too hot, only male babies hatch from their eggs.
