Great Barrier Reef

How Scientists are Using Sound Waves to Repopulate the Great Barrier Reef

Climate change is transforming the Great Barrier Reef, turning a once lively and colorful underwater ecosystem into a massive coral graveyard. Already, about 89% of the reef is dead or dying, putting the future of countless species of underwater life in jeopardy. Once teeming with life, large sections of the reef are now eerily quiet, which scientists believe led fish to abandon this habitat. In an attempt to revitalize this dying ecosystem, scientists have installed loudspeakers in various areas of the reef to make them sound as though they are healthy. Scientists have observed that reefs that sound lively attract fish to return to these habitats, paving the way for a potential future project to restore, at least in part, the once-lively and diverse ecosystem of the Great Barrier Reef.

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Using a process they call “acoustic enrichment,” which they described in a report published by Nature, scientists played noises including “the crackle of snapping shrimp and the whoops and grunts of fish” via a network of underwater loudspeakers. The scientists observed that twice as many fish arrived, and stayed, in areas of the reef that sounded lively compared to equivalent areas where no sounds were played. As the presence of fish is necessary for sustaining the ecosystems of coral reefs, scientists hope that attracting fish back to the Great Barrier Reef will help to kickstart other life in the region, potentially undoing some of the disastrous effects of rising ocean temperature levels. In other words, scientists hope that making coral reefs seem to be teeming with life will attract fish, beginning a natural recovery process.

As the field experiment lasted only six weeks, scientists have not yet had the opportunity to determine to what extent the repopulation of coral reefs impacts the larger surrounding ecosystem. However, the success of the experiment thus far has provided hope that interventions using science and technology can mitigate the damage of ecological collapse caused by climate change and other effects of human activity. That being said, while acoustic enrichment has proven to be an effective strategy for attracting fish, a number of threats to the Great Barrier Reef as well as the larger underwater ecosystem remain and will have to be accounted for to ensure the ongoing health of the ocean. These threats include climate change, overfishing, and water pollution.

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The span of time during which scientists observed the reef was too short for the fish to start breeding, and as of yet it’s unclear whether the fish will stay in this habitat long enough to spawn multiple generations of animals and to revitalize the surrounding coral. Coral depends upon the natural byproducts created by fish in order to survive, as they work as vitamin filters that allow the reefs to absorb nutrients. And as up to 85% of the oxygen in the atmosphere comes from the ocean, the health of underwater reefs also directly impacts life above land.

While large swaths of the Great Barrier Reef are entirely dead, a small percentage of the reef remains alive, albeit less populated with life than they used to be. Other projects to revitalize sections of the reef have also been conducted, with varying degrees of success. For example, scientists working for the Mote Marine Laboratory grew small pieces of reef in the laboratory and implanted these pieces alongside compromised sections of reef, which helped to regrow coral in just a few years, as the implanted sections of reef reproduced naturally. Additionally, the University of Hawaii is undergoing a project to selectively breed species of coral that are resistant to bleaching by using specimens that have shown to be particularly resilient. There is a long, uphill battle ahead to preserve the Great Barrier Reef, but scientific interventions provide hope that such an enormous task is possible.

Pirarucu Fish

Scientists Find Pirarucu Fish Have A “Bulletproof Vest” For Skin

Arapaima gigas, also known as the Pirarucu Fish, has truly always been nothing short of a river monster. They are native to South America and mainly found in Brazil/the waters of the Amazon rainforest. The waters they are known to inhabit are also heavily populated with piranha fish, and while the pirarucu can grow to up to 10 feet in length, scientists are constantly curious as to how fish survive in waters so densely populated with predators. 

This week, however, researchers from the University of California, San Diego and Berkeley, gained some groundbreaking information about the pirarucu’s defense system, that might even help us develop more effective body armor and aerospace designs. You read that right, a fish’s natural defense system might help assist humans in future aerospace designs. As previously stated these fish can grow to up to 10 feet in length, and up to 440 pounds! As if those two stats aren’t impressive enough, the fish can also breathe air and spend up to a full day outside of the water if it needed to. So it’s safe to say the pirarucu is already well equipped for defense, however, size doesn’t necessarily matter in this case scenario. Piranha’s may be smaller, but they’re equipped with teeth as sharp as razor blades, and a jaw that can bite up to 30 times its own body weight. The predators are actually known to take down fish larger than them, as they often attack their prey in groups and in a “frenzy” fashion, reeking utter chaos in any body of water they may live in. Which is why scientists were so curious as to how the pirarucu fish have coexisted with them as long as they have. 

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The first thing researchers normally look for in cases such as this, according to Reuters News, is some sort of armor that the animal has developed. All throughout history scientists have found dermal armor on various types of fish, mammals, and dinosaurs who are in environments with predators who use their sharp teeth as their weapon. So when they analyzed the pirarucu fishes skin only to discover it possessed the same qualities as a bulletproof vest, they weren’t surprised, but definitely in awe. 

“It is true that the natural armor is similar to artificial body armor because of the similar scale overlapping system. However, the natural armor such as these fish scales is tough and much lighter, without impeding body flexibility and locomotion. Remember that the fish scales were developed through hundreds of millions of years. They are very advanced,” said Wen Yang, a UCSD materials scientist who helped lead the study published in the Journal Matter.

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According to the published study, researches deeply analyzed the layers of skin and the scales of the fish. They found that the scales alone had a hard mineral outer layer, under that they found an inner layer of collagen which is tough but very flexible as well. These two elements layered on top of one another means that the scales can become deformed by a piranha bite, but they won’t be torn or ripped apart, which thus protects the pirarucu from detrimental injury.

“We were able to see how the collagen fibers deform without a catastrophic failure including the mechanisms of twisting, folding, sliding, stretching, delamination,” Yang said.

The study was backed by the U.S. Air Force Office of Scientific Research. The extensive tests done by the group of researchers concluded that the material in which the pirarucu’s skin is made up of is one of the toughest materials in the world that we know of. This is what could be beneficial to the future of how we create defense ware. Scientists hope to further work with and understand the scales structural make-up and transfer it to an artificial material that is man made and can hopefully be used in the future.