If you’ve spent any time snorkeling or scuba diving in places like Australia, the Galápagos Islands, or Polynesia, you don’t need me to tell you that exploring the underwater world can be an extraordinary adventure. And if you follow environmental news, you also don’t need me to tell you about the dangers climate change pose to the future of our planet’s marine ecosystems. So instead, here are fascinating facts about coral reefs that you might not know, from general info and the benefits of coral reef systems to a few of the world’s most impressive sites.
2. However, they rely on photosynthesis to survive. But the coral polyps aren’t doing the actual photosynthesizing. Microscopic algae, or zooxanthellae, live within the cells lining the digestive cavity of the polyp. As much as 90 percent of the energy a polyp needs comes from this symbiotic relationship. The other 10% comes from hunting the polyp does by extending its tentacles to catch prey.
3. They eat microplastics, and they like them. A study published in Marine Pollution Bulletin finds that corals, like fish, mistake plastic for prey and ingest it. The surprising part, however, is that researchers found they also like the taste. The scientists collected corals off the North Carolina coast and fed them a variety of options, which included sand and tiny bits of plastic. The corals overwhelmingly preferred the plastic.
“Corals in our experiments ate all types of plastics but preferred unfouled microplastics by a threefold difference over microplastics covered in bacteria,” Austin Allen, a PhD student at Duke University’s Nicholas School of the Environment, said in a statement. “This suggests the plastic itself contains something that makes it tasty.”
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4. Coral reefs are one of the most biodiverse marine areas on the planet, housing hundreds and even thousands of species. Reefs are an important location for finding food, shelter, mates and places to reproduce. Reefs also act as nurseries for large fish species, keeping them safe until they’re large enough to strike out into the deeper ocean.
5. Coral reefs are important to the development of new medicines. According to NOAA, “Coral reef plants and animals are important sources of new medicines being developed to treat cancer, arthritis, human bacterial infections, Alzheimer’s disease, heart disease, viruses, and other diseases.”
6. Coral reefs are so valuable to the fishing and tourism industries, as well as for protecting shorelines from storm damage, that destroying just 1 kilometer of coral reef means the loss of between $137,000 to $1,200,000 over a 25-year period, according to the World Resources Institute. And yet, nearly 60% of the world’s coral reefs are threatened by human activity.
How to keep corals alive ?
We’ve heard plenty about the rapid and dramatic loss of coral reefs over the last decades. According to some estimates, as much as half of the world’s coral has already disappeared in the last 30 years alone. Parts of Australia’s Great Barrier Reef had lost more than 70% of their coral by 2016, and some scientists are calling coral loss an extinction-level event.
Coral reefs are important not just because they’re incredibly beautiful places for humans to snorkel and dive in; they are also biodiversity hot spots: “A quarter of all marine fish species reside in coral reefs and 500 million people depend on these ‘underwater rain forests‘ for their livelihood,” according to the Worldwatch Institute. Here are few techniques to keep the corals alive
1. Cloud brightening
To save coral reefs in the ocean, one oceanographer is looking to the skies for help. Daniel Harrison, a University of Sydney researcher, is working on a method called “cloud brightening,” which would use clouds to essentially provide a protective barrier over coral reefs. Cloud brightening involves pumping sea water through a filter and using a fan to spray the water toward the clouds. The water would evaporate in the sky, but the salt particles in the water would stay behind and condense with other water — therefore making clouds appear brighter. The theory is that brighter clouds would deflect the sun’s rays, which would keep the ocean water temperature cooler and in turn hopefully prevent coral reefs from bleaching and dying.
2. Using the power of sound
The latest unorthodox solution involves loudspeakers and a bit of deception. Healthy reefs are relatively noisy places, and these scientists used that to their advantage, playing the sounds of a healthy reef in an unhealthy reef environment to see how the ecosystem would respond. An international team of researchers from University of Exeter, University of Bristol, and Australia’s James Cook University and Australian Institute of Marine Science, used this “acoustic enrichment” in a six-week experiment in the Great Barrier Reef. They published their work in Nature Communications.
3. Assisted evolution
This method uses coral fragments and relies on a survival of the fittest approach, focusing on those that can tolerate, survive and even thrive in hotter, more acidic water. A team of scientists in the Florida Keys break off pieces of coral and submerge them in hot, acidic water tanks. The fragments that survive are attached to artificial “trees” underwater so they can continue to grow before being transplanted back to the reef from which they were taken. It’s a painstaking process that involves replanting each individual fragment one-by-one. Their efforts appear to be paying off.
Some corals, like brain coral, can take 100 years to grow to a square meter. A new technique involves growing a small part of one of the larger boulder corals and then attaching it to an old, bleached-out base. Due to a natural stress response, the baby corals grow and cover the surface of the old coral more quickly than starting from scratch. Because corals depend on size rather than age to reproduce, the young corals reach maturity in less time and start reproducing.
5. Genetic selection
Corals have been around for 500 million years (for comparison, humans have been here for only 2 million). So within their DNA they have the tools to deal with change — just not as quickly as change is happening now. So scientists have been going to areas where corals have been subjected to abuse — like Oahu, where some corals survived raw sewage being dumped on them, or Australia, with the aforementioned mass-bleaching events, or even the Red Sea, where corals survive high temperatures — and collecting samples of what’s left.
Retrotransposons, also known as “jumping genes,” are genes that replicate and mutate. In 2017, researchers from King Abdullah University of Science and Technology in Saudi Arabia discovered genes associated with heat resistance in the symbiotic algae that live within corals. In theory, the genes would make the algae more heat-tolerant, and if the algae can survive higher temperatures, the hope is that corals would, too.
6. Adding electricity
In some areas of the planet, scientists are rebuilding coral reefs with Biorocks, which are steel-framed structures with a low voltage of electricity pulsing through the frame. The electric current passes through sea water and creates a chemical reaction that coats the coral with limestone minerals similar to the natural coating created by young coral. According to the non-profit Global Coral Reef Alliance, Biorock reefs help speed the growth of coral and make them more resistant to increases in temperature and acidity.
7. Gene storage banks
The worst-case scenario is that we lose many or all corals in the next 50 to 100 years. We need to have a repository of their genetic information so there’s still a possibility of restoration even if they disappear from the wild.