Article reprinted from "Gezhi Discourse Forum"
From more than a decade ago to the present,
What is the condition of our reefs?
There are two sets of data: 80% of the corals near the shore have disappeared;
The coverage rate of reef-building stony corals on outlying islands is from 50%-60%
That's down to 10%-15% now.
Huang Hui· Researcher, South China Sea Institute of Oceanography, Chinese Academy of Sciences
The 15th issue of The Grace Campus | December 15, 2020 Beijing
Good afternoon, I am Huang Hui from the South China Sea Institute of Oceanography, Chinese Academy of Sciences. On behalf of myself and my team, I would like to tell you the story of our coral cultivation and research in the South China Sea.
One-third of the world's reef-building stony corals are distributed in China
First of all, I will show you a picture of a beautiful coral reef. My main research object is coral reefs, and the framework organism of coral reefs, reef-making stony corals. Inside the reef, we can see a lot of lumpy, branched reef-building stony corals, which we call frame organisms.
I am often asked by the audience: Teacher Huang, are corals animals or plants? I want to answer this question first. Many people say that corals are stones, which also makes sense, and Hainan calls corals "sea stone flowers". What we often see, the white ones are the skeleton parts of the reef-building coral, so it's actually a stone, but it's a coral skeleton that contains calcium carbonate.
It is also said that coral is a plant because it branches like a tree at the bottom of the sea. In fact, coral is an animal, it is a very low class coelenterate. We eat jellyfish and have seen jellyfish, and corals are close relatives of jellyfish, both of which belong to coelenterates.
Corals have a lot of tentacles, what is it? - Polyps. Each coral has thousands of polyps living together, and it is very low and dependent on groups. This polyp looks like it's very large, but it's actually very small, and the average polyp is only a few millimeters to a few centimeters in size.
The tentacles of the polyps are colored. Why are there colors? Because it symbiosis with algae. So why many people say that coral is like a plant is because its symbiotic algae need sunlight for photosynthesis. The main source of nutrients for corals is the product of photosynthesis of symbiotic algae, and corals can grow when there is sunlight. But the polyp has tentacles, and at night it can also eat small bugs.
Thousands of corals make up corals, corals die and leave bones of calcium carbonate, new corals continue to multiply, grow, and deposit on old corals, what has been formed over thousands of years? - Coral reefs, coral islands. The largest coral reef in the world is Australia's Great Barrier Reef, with a total of 1900 km.
Coral reefs are mainly distributed in the shallow tropical sea, that is, between 30 degrees north and south latitudes, in the red area of the map. Our country's coral reefs are mainly distributed in the South China Sea on the mainland, as far north as Dongshan in Fujian and Hong Kong. However, the reef-building corals here cannot be reefed, because at the northern edge, it is only called the community of reef-building stony corals.
Hong Kong is mainly distributed in the east and northeast, and the most should be in the area of Dong Ping Chau. If I remember correctly, there are 83 species of reef-building corals. To the south, the coasts of Guangdong Leizhou Peninsula, Guangxi Weizhou Island, and Hainan Island are all reefs and reefs. Further south to the Paracel Islands, Zhongsha Islands, Nansha Islands, is a typical island reef.
Scientists count 38,000 square kilometers of coral reefs on the continent, accounting for 13.5% of the total area of coral reefs in the world. There are about 300 species of reef-building corals on the mainland, about 800 species in the world, and we account for about 1/3 of the world. Therefore, the research and protection of global coral reefs on the mainland is still very important.
El Niño-induced damage
Completed: 30%/////////
Seeing these two pictures, everyone may be confused, what does this have to do with coral reefs?
This is a phenomenon very much related to coral reefs – El Niño. Many people may come across this word in media news or weather forecasts, what does El Niño mean? Refers to an abnormal temperature rise.
The picture on the left is a tarmac road in Delhi, India, where the zebra crossing has melted badly due to too high temperatures. El Niño can also trigger abnormal weather, such as flood breakouts.
An increase in temperature causes the water temperature to rise. Although the reef is distributed in tropical waters, it is actually only suitable for living in areas below 28 degrees of water temperature. Abnormal temperatures, 30 degrees, 31 degrees will also cause a large number of corals to bleach and die.
The first El Niño phenomenon that attracted widespread attention was in 1998, when about 1/3 of the world's coral reefs died of bleaching, which was spectacular. Many of the islands and reefs in the Pacific Ocean are white from the air, so global warming has attracted everyone's attention.
There was a second El Niño in 2010, mainly in the Indian Ocean. The most recent was in 2015-2016, when the greatest damage to the Great Barrier Reef, where 60% and 70% of coral reefs in the north were bleached to death, was a cause for much concern.
Witness the evolution of coral reefs
Completed: 40%/////////
I graduated with a master's degree in 1996, and both my bachelor's and master's degrees are in aquaculture. What is aquaculture? Didn't my mother say she would just learn to raise fish? After graduating from the master's degree, I did not find a suitable job because of the yin and yang.
I remember staying at the Institute for those two months. Someone says you don't have a job yet? I said yes, wait and see the right one. As a result, I was introduced to Mr. Zou Renlin, the founder of coral research in the mainland. It was one of the things I was very fortunate to do when I graduated with a master's degree and came under his door.
In 1999, I was seconded to Beijing to work for the National Natural Science Foundation of China. In the past two years, I have been exposed to some of the continent's top marine science scientists. This is not an opening of a window in front of me, but an opening of a world. I made up my mind at this time: I want to do scientific research, I want to study coral reefs. So I started a working PhD and started studying coral reefs.
What have we done since then? First, we need to understand what the state of coral reefs, the coral reefs of the mainland, is.
We have traveled all over the country's coral reefs, from Dongshan in Fujian, along the coast where the coral reefs of the mainland are distributed, all the way to the Paracel Islands and the Nansha Islands. There are coral reefs all over the place where we went to investigate.
We look like the Institute of the Academy of Sciences, but I'm going to complain about a few hardships here. When you come to our team, whether it's a student or a job, the first thing you do is to learn to dive and get a diving license. We all have to be able to dive, and only by working on the front line can we get the data of the most front line. We are also very sad, to write articles, to do experiments, to insist on going to the front line of underwater investigation, but also to do farmers underwater, planting corals.
I have witnessed the evolution of coral reefs. From more than a decade ago to the present, what is the condition of our coral reefs? There are two sets of data: 80% of inshore corals have disappeared; the coverage of reef-making stony corals on outlying islands, like forest cover, has dropped from 50%-60% to 10%-15% now. Of course, not only the mainland, but also the whole world is so miserable, it is also about 15%.
In addition to global warming, excessive fisheries and coastal exploitation, sediment, pollutant emissions and overfishing have all wreaked havoc on coral reefs. The two pictures, one is fried fish, and the other is a drift gillnet in a reef dish.
We have "The Rich Paracel Islands" in our primary school textbooks, and we have all seen movies about the beautiful Paracel Islands, and there is a song that is very famous. I still remember the corals, turtles, lobsters, sea cucumbers pulled by boats in that film... What happens to Xisha now? What are the results of overfishing? From the paradise of fish, shrimp, shellfish and algae to a dead silence, there are no living things left.
And in 2007, the last straw of devastation occurred – the explosion of coral's natural enemy, the long-spined starfish. The picture on the right is a 2008 photo we took underwater on an island in the Paracels, surrounded by black, corals eaten by long-spined starfish.
A long-spined starfish can eat two square meters of coral a day, it does not like to eat the middle of this white - tube star coral, after eating all the surrounding areas, there is only this piece left, we call it "The Last Supper". Dozens of long-spined starfish lie on top of it, and every time I see this picture I am terrified.
The first photo below is of the past Xisha, and the second is of the present. The picture was pretty good, and even more frightening, a detritus, nothing.
I remember the first time I went diving in Paracel was in 2002, and I was shocked. Of course, I also brought some "souvenirs" back, what "souvenirs"? The first time I went there was no experience, the sun protection was not done well, and the face was sunburned with a lot of spots. When I was young, I was still beautiful like a flower, and now this spot can no longer be removed.
Although the sunburn is very bad, but I am very shocked, now I can close my eyes can remember that scene: the water is transparent, the coral is almost 100% coverage, dense, the fish are colorful, and you can see a lot of snails.
Doing an investigation at that time is also an act of destroying coral reefs now. Divers sometimes tell us: Let's go catch some snails and come back to eat. We finished our work, there was still a little gas left, and we could pull a round of snails in five minutes to come back and add food. Now to dive in the Paracel Islands, I dive a bottle of gas, 40-50 minutes, and I was very excited to see both snails, so I think the contrast is really too strong.
Coral Reef Restoration: "Afforestation" on the Seabed
Completed: 70%/////////
Coral reefs are important, they are tropical rainforests on the seabed, with high biodiversity, and many marine life thrives here. Coral reefs also have a function that provides fishery resources – statistics say 700 million people depend on coral reefs for life, getting protein from coral reefs.
It also has a role - to protect the reef and revetment, just like mangroves. The three-dimensional structure of coral reefs is uneven, and when the waves pass by, the coral reef can reduce a lot of the energy of the waves. So when typhoons, storm surges and tsunamis come, passing through coral reefs, seagrass beds or mangroves, they will lose a lot of energy.
What are the consequences of not having a coral reef? The picture above is the Indian Ocean tsunami, the coastal damage is too severe, when the tsunami comes, the waves directly hit the shore, causing very large losses, killing many people.
In the face of the current situation of coral reefs, we are also thinking, what should we do? Human destruction has caused its degradation, and we should do something for coral reefs as well. My own aquaculture background has played a role here. We began research and development of technologies for the restoration of coral reefs and began to study the construction of nurseries.
Planting corals on the seabed is very similar to planting trees on land, and it is necessary to have seedlings and build nurseries. The picture above is a tree-type nursery, which we learned from abroad. At the beginning of scientific research, we are lagging behind others, we must admit that we are backward, but we have been constantly catching up.
We also have to study its reproductive biology – when do we lay eggs? How do fertilized eggs divide? How do floating wave larvae attach? We all need to observe.
During the breeding season, our team worked very hard. Corals do not lay their eggs until 9 or 10 o'clock in the evening, and for two or three days near the time of laying eggs, we all stay underwater at night to observe when it lays eggs, collect and breed these fertilized eggs, because its survival rate in the sea is very low. We bring it to shore, breed a lot of larvae, and then release it, which is also a means of restoration.
We built 40 acres of nurseries. When the first phase of the nursery was built, about 20,000 or 30,000 small broken branches were collected in the wild. Up to now, in these 40 acres of nurseries, almost 70,000 seedlings can be produced a year. We have built 300 acres of restoration area, no longer need to collect seedlings in the wild, are their own seedlings, sow these seedlings to the seabed, repair coral reefs.
It's easier said than done, but planting trees on the seabed is much harder and harder than on land. A set of equipment more than 30 pounds, every time they go into the water they are stepping down, I turned over, with equipment can not stand up, really heavy. We have to carry the equipment underwater and we have to drive piles. Hitting a nail under the water, because of the weightlessness, the sledgehammer has to be hit three or four times to hit a nail, which is a completely different concept.
And we also have to go out of the island, such as in Sanya, Xisha, we do research to charter a boat to go to sea, sometimes encounter storm surges, typhoons or big waves. Many people ask me if I feel seasick, what does it feel like to be seasick? It is better to live than to die.
At first, when I was on the boat, I thought that I would not faint in the water, but in fact there were waves under the water. Biting the breathing mouth, will you vomit in the water? Will also throw up. Loosen the breathing mouth and spit it out, then bite back again. These experiences are really many, much more difficult than on land, but we are not afraid of difficulties.
We have planted so many corals, but in fact, we have accumulated many, many lessons to make it. I remember when we did better for the first time in Sanya, we went to check how the corals looked after half a year, and when we finished it, a new pier was built next to it, and our original nursery was completely covered, and the results were gone.
I would like to thank my team for not being able to do so much on my own. Our team has staff and students working together for so many years. Of course, whether it's me or the team, our strength is very small, but I'm still confident that more and more people will be involved in our work.
I would like to appeal to you here, starting from yourself, using less plastic products; eating less of the creatures that directly harvest coral reefs, it is too important to manage the mouth; buy less coral, bricks, snails and other handicrafts. We should have more reverence and love for nature, for coral reefs, and for the ocean.
Thank you.
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