Li Xiubao: Planting corals on the seabed to protect the "tropical rainforest in the blue ocean"

(Li Xiubao, Professor of the College of Oceanography, Hainan University, Director of the Coral Reef Branch of the Pacific Society)

Li Xiubao first met coral more than 20 years ago. At that time, he had just entered the South China Sea Institute of Oceanology, Chinese Academy of Sciences to study for a master's degree, and he didn't even know how to dive. His mentor, Huang Hui, was a humorous and outgoing woman. The first thing she said to him when she saw him was: Go learn how to dive as soon as possible.

Soon, his mentor took him to the Luhuitou area in Sanya to investigate coral reefs. Li Xiubao didn't know how to dive at that time, so he could only snorkel. But he always remembered the spectacular scene he saw that day: the sea was azure blue, schools of fish were swimming around, and large colonies of staghorn corals stood on the seabed.

Some people compare coral reefs to "tropical rain forests in the blue ocean": they cover less than 0.2% of the seabed, but provide a living environment for a quarter of marine animals. And the coral reefs that Li Xiubao saw that day were indeed as lively as tropical rain forests.

Unfortunately, this excitement did not last long.

Li Xiubao found that although his diving skills were getting better and better, it was difficult for him to see the magnificent scenery of the past, especially the staghorn corals, which were rarely seen in field surveys today.

Staghorn corals are very sensitive to water quality and the environment. With the emergence of coastal development, overfishing, pollution emissions, extreme climate and other problems, scientists have found that many near-shore corals have disappeared, and the coverage of offshore coral reefs has also dropped sharply. From the air, you can see that the islands and reefs in the Pacific are all white, and deep in the seabed, the fish have gone, leaving only broken reefs and a dead silence.

The most striking contrast for Li Xiubao is the degradation of the islands and reefs in the Xisha Islands. When he first went there in 2006, the coral reef ecosystem was spectacular and lively; within two years, the entire submarine island reef was destroyed and covered with coral fragments.

Why has there been such a big change? The most intuitive and superficial reason is the outbreak of long-spined sea stars. Long-spined sea stars feed on corals, and one long-spined sea star can eat two square meters of coral. If long-spined sea stars reproduce in large numbers, they can destroy large areas of coral in a short period of time.

The deeper reason behind this is the imbalance of the ecosystem. Li Xiubao and his team found that the fish density in the Xisha Islands has been reduced by half in the past two years. As the number of natural enemies has decreased, the long-spined sea stars have multiplied in large numbers and destroyed the coral reefs. So, what is the reason for the reduction of fish? It is mainly due to overfishing in the Xisha Islands. In other words, the most fundamental problem behind this is still human activities.

Of course, the reasons for coral degradation in different areas are slightly different, and Li Xiubao's team conducted investigations in various places in order to clarify the specific factors. Because only by protecting corals can we protect thousands of marine creatures.

"Humanity must do something." In 2011, Li Xiubao's marine ranch team at the State Key Laboratory of South China Sea Marine Resources Utilization at Hainan University, in cooperation with Wuzhizhou Island in Sanya, Hainan, officially launched my country's first tropical "marine ranch" project, attempting to cultivate corals on the seabed.

To "plant corals" on the seabed, you first need to build a nursery on the seabed to cultivate coral "seedlings" and then transplant them to the places that need restoration. Some of these "seedlings" are coral fragments picked up from the seabed, and some are cultivated from coral spawning. Coral spawning usually takes place at night, so two or three days before the coral spawning, Li Xiubao and his team wait on the seabed every night, for fear of missing this spawning.

After the seedlings are cultivated and mature, how to transplant them is also a problem. In order for corals to settle in the ocean, they need to stably attach to hard surfaces. Li Xiubao and his team have tried various materials as reefs according to different environments. For example, on Wuzhizhou Island in Sanya, which is rich in volcanoes, they used volcanic rocks to fix the reef bottom, and also tried using iron nails and old sunken ships. These reefs not only allow corals to attach, but also provide habitats for fish, sea urchins, conchs and other marine animals with recovery functions.

Li Xiubao monitors the effects of coral reef restoration on Wuzhizhou Island in Sanya

Planting corals on the seabed sounds a bit romantic. In fact, all operations become difficult underwater. Before entering the water, Li Xiubao and his colleagues were carrying more than 30 kilograms of equipment. Those with more strength could stand up and step into the water, while those with less strength could only flip directly into the water. Even those with rich sailing experience will inevitably get seasick when the sea is too rough. Sometimes, when the seasickness is too unbearable, you jump into the sea to calm down, but you find that there are also waves in the water, and you have to vomit.

Fortunately, their efforts were not in vain.

For Li Xiubao and those who are engaged in coral reef protection, restoring coral reefs is a long and complicated task. All they can do is give their best and leave the rest to time.

Moreover, in Li Xiubao's view, coral reef restoration is not the only answer to protecting corals and marine ecology. In some waters, the water quality is very poor, and even if corals are transplanted, it is difficult for them to survive. In other waters, the ecological environment is suitable and there are some functional organisms. Even if they are not restored, they can slowly recover in two years. Therefore, it is necessary to consider various factors according to local conditions. The most important thing is to reduce the survival pressure of corals from the source.

His thinking is prudent and calm like a scientific worker: "In an era of feverish coral reef ecological restoration, we need to think calmly. Blind restoration may cause damage instead."

References:

CNR: Li Xiubao | 18 years, tens of thousands of hours of diving, just to protect the Coral Sea!

2. Hainan Provincial Department of Science and Technology: Professor Li Xiubao of Hainan University: 18 years of hard work to build a beautiful home for corals

Author: Cheng Guan Popular Science Creator

Review丨Editor of Suqin Ocean Publishing House

Jia Hepeng Professor, Doctoral Supervisor, School of Media, Soochow University