This article is reproduced from: Zhang Peidong, a professor at the School of Fisheries, Ocean University of China, and his students are wearing diving equipment and taking samples underwater. "The key to the survival of seagrass is to run the 'land-sea relay' of seed collection, seedling raising and planting."
Seagrass has experienced hundreds of millions of years. It is the only type of higher angiosperm on earth that can live completely in seawater. Large areas of continuous seagrass are called seagrass beds, and together with mangroves and coral reefs, they are known as the three typical offshore marine ecosystems. However, due to the dual impact of human activities and changes in the natural environment, about one-third of the world's seagrass beds have completely disappeared and are rapidly degrading at a rate of 7% per year.
The picture shows the eelgrass seeds picked by teachers and students of "Shandong Rongcheng Eelgrass Science and Technology Yard". Xinhua News Agency Photo by Li Xinjun
More than ten years ago, Zhang Peidong began to pay attention to the restoration of seagrass beds. He set his sights on eelgrass, the dominant species of seagrass in temperate waters. When Zhang Peidong was conducting research in Weihai, Yantai, Shandong, he discovered that there was once a large area of eelgrass in Rongcheng Swan Lake. This eelgrass is a major food source for creatures such as whooper swans. In the 1970s, the outlet connecting Swan Lake to the open sea was blocked. The eelgrass at the bottom of Swan Lake was unable to adapt to environmental changes and almost completely degraded. The number of whooper swans wintering here dropped sharply from more than 10,000 to a few dozen.
Later, the mouth of Swan Lake was reopened, and the eelgrass began to slowly recover. However, due to the extremely low retention rate of eelgrass seeds under natural conditions, it may take hundreds of years to form a healthy ecosystem again by natural recovery alone.
In 2008, Zhang Peidong and his colleague Li Wentao hit it off with the Mashan Group, which is committed to marine ecological restoration, and took root on the banks of Swan Lake. This year is the 15th year that they have led students to study seagrass cultivation in Rongcheng, and it is also the second year that the "Shandong Rongcheng Eelgrass Science and Technology Yard" was officially established.
"When will the eelgrass germinate, when will it bloom, and when will the seeds mature? At the beginning, we knew nothing about these." Zhang Peidong said, "If you pick it too late, the eelgrass seeds will naturally fall off into the sea. If you pick it too early, , the seeds have low starch content and do not germinate. After a long period of exploration, we finally figured out the growth pattern of eelgrass and found the best time to pick seeds."
The picture shows the "Shandong Rongcheng Eelgrass Science and Technology Yard" Seedling workshop. Xinhua News Agency photo by Li Xinjun
In the nursery workshop of "Shandong Rongcheng Eelgrass Science and Technology Yard", the sound of seawater circulation is endless. In the seed germination pool, rectangular flower pots are arranged neatly, and the seeds under the "formula mud" are germinating. "This is the artificial cultivation technology of eelgrass seedlings that we developed for freshwater germination promotion and low-salt seedling cultivation." Li Wentao introduced, "When we started to promote germination, we used fresh water. As time went by, the salt in the water in the germination pool The temperature must also be gradually increased to allow the eelgrass seedlings to slowly adapt to the salinity of the seawater before transplanting them to the seabed." With these technologies, eelgrass seeds that take more than half a year to germinate in natural environments can germinate within a week at the fastest.
Outside the seedling workshop, staff are making sowing bags used in the "flat carpet sowing method". They put the "formula soil" in a jute bag, smoothed it, sealed it, sewed a basalt grid on one side, punched holes evenly on the other side, and then used a syringe to take out the seeds and inject them. "This is part of our engineering optimization." Zhang Peidong said, "When sowing with the grid facing upward, the eelgrass seedlings can be well fixed. After using this sowing method, the seed retention rate can reach almost 100%."
Workers are attaching basalt gratings to jute bags filled with "formulated soil." Xinhua News Agency photo by Li Xinjun
In order to improve the efficiency of "planting grass", teachers and students have developed eelgrass vegetation construction technology for plant transplantation such as frame-fixed seedlings, hemp rope-clamped seedlings, and matrix-wrapped seedlings, as well as the "trinity" eelgrass and seagrass bed ecology. Repair innovative applicable technologies.They have also developed multiple sets (sets) of seagrass bed auxiliary restoration facilities with independent intellectual property rights, such as plant direct insertion machines, seed direct seeding machines, seeding mud block preparation machines, seedling clamping machines, and seedling rope transplanting machines, which have increased work efficiency several times.
Up to now, teachers and students of "Shandong Rongcheng Eelgrass Science and Technology Academy" have applied for more than 10 invention patents, published more than 50 SCI papers, and took the lead in the preparation of a group standard and an industry standard. In the past 15 years, this group of "grass growers" at the bottom of Swan Lake have participated in no less than 10 submarine ecological restoration projects, and have restored and conserved more than 20,000 acres of seagrass beds in the Yellow and Bohai Seas.
"This year, the more than 20 million eelgrass seedlings we have cultivated will be multiplied into the waters of Swan Lake and Fish Pond Bay." Li Wentao said. At the bottom of Swan Lake, nearly 50% of the eelgrass beds have been restored; by the banks of Swan Lake, groups of white whooper swans are dancing, playing leisurely in the lake. Liu Zhibin, a ranger at the Rongcheng Whooper Swan National Nature Reserve, told reporters that with the recovery of undersea eelgrass and the improvement of the surrounding ecological environment, the number of whooper swans coming to overwinter each year can reach a maximum of more than 8,000.
By the Rongcheng Swan Lake, big swans are flying. Xinhua News Agency photo by Li Xinjun
"In the past, people asked whether this kind of grass could be eaten and whether it was delicious. Now, everyone asks what is the use of this kind of grass and how to grow it to survive." Li Wentao said, "Now, we have been able to If we run the 'land-sea relay' well, I believe we can plant more 'oases' on the seabed."