Original title: The team of teachers and students of Ocean University of China repairs and maintains seagrass beds to protect marine ecology
In 16 years, more than 20,000 acres of "submarine grassland" have been planted (guardian of lucid waters and lush mountains)
Seagrass in the waters of Swan Lake. Courtesy of Ocean University of China
Schematic diagram of seagrass bed ecosystem. Courtesy of Ocean University of China
Core Reading
Seagrass is a terrestrial plant that has evolved into a higher plant that adapts to the marine environment, and plays an important role in the protection of marine ecology.
Over the past 16 years, Zhang Peidong, a professor at the College of Fisheries of Ocean University of China, and his team members have restored and conserved more than 20,000 acres of seagrass beds in the Yellow and Bohai Seas, and established a relatively complete ecological restoration technology system for temperate seagrass beds.
With an oxygen cylinder on his back and diving goggles, Zhang Peidong took a deep breath, jumped over, and "plopped" into the water.
As the body dives, the underwater scene comes into view: the seaweed swaying with the waves, clusters and clumps, stretching into the distance; Take a closer look at the grass, there are really a lot of "treasures" underneath, conch, crab, shellfish...... Zhang Peidong took the waterproof paper, observed it, and wrote down the latest growth status of seagrass.
Seagrass is a terrestrial plant that has evolved into a higher plant adapted to the marine environment, and one or several types of seagrass grow in succession to form a vast and soft "submarine grassland", that is, a "seagrass bed".
In Swan Lake, Rongcheng City, Weihai, Shandong Province, Zhang Peidong, a professor at the School of Fisheries of Ocean University of China, and his team members have spent 16 years planting seagrass on the seabed to protect the marine ecological environment.
Where does research begin?
Immerse yourself in research to find out the growth characteristics of seagrass
In the winter of 2008, Zhang Peidong and his colleagues went to the Swan Lake area for research. They found that the images of hundreds of whooper swans dancing in the past were gone, and the cold wind blew, and only a few dozen whooper swans were scattered around foraging.
Why are there so many whooper swans? "The villagers say it's because there is less eelgrass." Zhang Peidong explained that eel grass is a seagrass that grows widely in temperate seas, and is an important food for whooper swans to overwinter, which plays an important role in protecting the local marine ecology.
In the 70s of the last century, in order to protect marine fishery resources, the local area of Swan Lake and the open sea were blocked, resulting in the deterioration of the water exchange capacity, the decline of water quality, and the difficulty of eel grass to adapt to environmental changes, and the degradation of a large area. Later, when the plug was removed, the seagrass bed began to recover naturally, but very slowly.
It's not just the Swan Lake area. After surveying multiple sites, they found that more than 80% of the seagrass beds in the temperate coastal waters of the continent had disappeared at that time, and the biodiversity of shallow waters was declining. Therefore, they decided to lead the students to "plant grass" and explore the restoration of seagrass bed ecosystems together.
"If you want to 'grow grass', you have to carry out a lot of research and experiments in the early stage to understand the growth characteristics of seagrass before you can take targeted measures." Zhang Peidong said that it took them 10 years to complete this process alone.
On the basis of consulting a large number of literatures, they simultaneously carried out indoor experiments, "what is the temperature, salinity, and light intensity that eelgrass likes, we have to find out through comparative tests again and again." Team member Li Wentao said.
Indoor testing is adjunct only. "When does the eel grass bloom and seed in the natural sea? When do the seeds germinate after they fall off? …… These must be ascertained through sea surveys. To this end, Zhang Peidong and his team members learned to dive. The biggest difficulty in the investigation is the lack of understanding of eel grass and the difficulty of mastering the method, such as flowering is closely related to temperature and other conditions. When I go late, the flowers are all finished, and the best sampling period is often missed. He said.
How to overcome these difficulties? The team members took root on the seaside, ate and lived with the fishermen, and insisted on going to the sea to take samples regardless of the cold and heat. In winter, the seaside is bitterly cold, but this is the time when whooper swans come to spend the winter, and it is also an important time to observe seagrass. "At night, when the tide is low, it is easy to investigate, so we often go out to sea in the early hours of the morning, first chiseling through the thick ice, and then going down to the icy sea water to take samples." Zhang Peidong said with a smile, although he wore thickened protective clothing, it was still difficult to withstand the cold.
After 10 years of painstaking investigation, the team's understanding of eelgrass gradually became clearer, clarified the growth characteristics and growth environment, and laid a solid foundation for subsequent restoration work.
How to achieve high-quality restoration at a low cost?
According to local conditions, the "land-sea relay" improves the survival rate of seagrass
On the shore of Swan Lake, a small courtyard sits here. The sign on the doorpost reads "Shandong Rongcheng Eel Science and Technology Courtyard".
Inside the room, there are various test devices on the table. Several students are crouching on the ground, sorting out plant samples they have just taken from Swan Lake.
The seemingly unsightly science and technology courtyard is connected to the blue sea at one end and university scientific research at the other——
In 2008, Mashan Group Co., Ltd., which is also committed to marine ecological restoration, provided factories and office space not far from Swan Lake as the main research venue for the teachers and students of Ocean University of China. In 2022, the cooperation will go further, and Ocean University of China and Masan Group Co., Ltd. will jointly establish a science and technology academy here. After the teachers and students took samples from the sea, they could rush to the small courtyard to "strike while the iron is hot" to do the experiment.
"However, it was a small-scale trial in the early stage, and it was not too cost-conscious. The next step is to conduct large-scale verification of the marine area to see if the solution is feasible and whether a low-cost, high-quality restoration solution can be found. Zhang Peidong said that after repeated trials, the team finally retained three main restoration methods.
In some areas where eel grass is degraded due to human factors and other factors, they have to "diagnose" the cause of eel grass degradation like a "doctor", and then restore the habitat in a targeted manner. "For example, some ponds are connected to the sea, and many years ago shrimp and sea cucumbers were raised, and there were some discarded nets in them, which hindered the growth of seagrass, so we had to find a way to remove the nets and restore the space for the eels to restore naturally, which is the habitat restoration method." Zhang Peidong said.
However, if the recovery rate is too slow by natural means, how can the repair speed be accelerated with the help of manual means?
Seagrass is a higher plant that reproduces differently than algae commonly found in the ocean. "It can reproduce sexually and be repaired by sowing seeds, or it can reproduce asexually and be repaired by transplanting plants." Zhang Peidong introduced.
How to sow by the sowing method? In the workshop of the science and technology courtyard, you can see that the eel seed preservation pond is soaked with dense seeds, like green wheat kernels. "The eel grass seeds have a low retention rate in the natural environment, and we collect them manually from different sea areas." Zhang Peidong picked up a bag of seeds from the water, "After the seeds are sorted, they can be put into natural waters by artificial sowing. ”
Compared with land sowing, seabed operations are much more difficult. "Seaweed seeds are very light, and if they are scattered in the sea, they will be carried to the shore or deep water by the currents, or they will be eaten by animals, and they will not germinate." Zhang Peidong said that they have created their own sowing methods such as sacks of seeds, gauze wrapping seeds and mud block wrapping seeds, which have greatly improved the survival rate of seeds.
How to move the transplant method? "If you collect an eel from the seabed and transplant it to a seabed location that needs to be repaired, it may naturally clone new patches of grass beds once successfully colonized, but this method is somewhat unknown." Zhang Peidong said that they came up with the idea of a "land-sea relay" – collecting seaweed seeds, raising them artificially and then transplanting them.
"There is also a big difficulty in artificial seedling breeding, that is, the seed germination period is too long. Most temperate seagrasses are stubborn seeds with a hard seed coat that matures and falls off into a long dormant period, which can take more than 80 days from collection to germination. Li Wentao said.
Can seeds germinate in a short period of time? In the seed germination pond, there are some long flower pots, and in the soil in the pots, eel grass seeds are quietly germinating. "Fresh water is used for germination, and as the seeds grow, the salinity of the water should increase little by little, and after the seedlings are grown, they will slowly adapt to the salinity of the seawater, and then transplant them to the seabed." Li Wentao introduced that in the seed germination pond, eel seeds that can germinate in the natural environment for more than 80 days can germinate in about 10 days at the earliest.
While exploring and trying, they established a relatively complete technical system for ecological restoration of temperate seagrass beds. Does the availability of repair technology mean that it can be used in a large area? Zhang Peidong shook his head: "Restoration should respect science and adapt measures to local conditions. ”
In 2022, the industry standard "Technical Specifications for Seagrass Bed Construction" led by the team of teachers and students of Ocean University of China was approved and released by the Ministry of Agriculture and Rural Affairs. This set of technical specifications specifically puts forward the main factors and conditions that should be paid attention to in the site selection of seagrass bed ecological restoration, describes the construction methods such as plant transplantation, and becomes the first seagrass bed ecological restoration technology industry standard in mainland China, which provides a technical basis for standardizing and guaranteeing the ecological restoration project of seagrass beds in mainland China.
What is the new breakthrough in "planting grass"?
Repair and use of "two legs" to walk
There is a small white boat in the science and technology courtyard, about two feet long, shaped like a motorboat. If you look closely, there are 8 small holes in the corners.
This is the "unmanned seeding boat" developed by Zhang Peidong and his student Peng Liye. "In the past, we had to go to the sea to sow seeds, but the efficiency was low, the sowing was uneven, the seeds were easy to stick, and the utilization rate and survival rate were not high." Peng Liye said that when he communicated with the teacher, he thought of aerial seeding on land, "In the desert, people will fly planes to sow saplings, can we develop a machine to sow seeds in the sea?" ”
After receiving the affirmation, Peng Liye began to develop an unmanned seeding ship. "Wrap the seeds in a layer of material to avoid sticking, while adding weight to prevent them from being washed away; When designing the boat, refer to the automatic bait, and spray the seeds through 8 blowholes. Peng Liye said, "When using, people do not need to go to the sea, standing on the shore, the remote control machine can evenly sow seeds." ”
In order to improve the efficiency of "planting grass", the team teachers often encourage young people to "explore boldly and innovate". In addition to the unmanned seeding machine, the teachers and students have also developed auxiliary restoration facilities for seagrass beds with independent intellectual property rights, such as plant direct inserting machine, seed direct seeding machine, sowing mud block preparation machine, seedling clamping machine, seedling rope transplanting machine, etc., which have increased the work efficiency several times.
In Zhang Peidong's view, the current restoration of seagrass beds is not only the integration of technology and disciplines, but also the integration of industry, so as to realize the "two-legged" walk of protection, restoration and development and utilization.
"In the future, we should try to organically combine the ecological restoration of seagrass beds with carbon sequestration and sink increase, green ecological pastures, high-value ecological products, and fishing and tourism culture to achieve a win-win situation of ecological and economic benefits." Zhang Peidong said that in addition to sequestering carbon and increasing sequestration, they have already tried to cultivate sea cucumbers and oysters in some restored areas.
Up to now, the team of teachers and students of Ocean University of China has participated in more than 10 seabed ecological restoration projects in China, and has restored and maintained more than 20,000 acres of seagrass beds in the Yellow and Bohai Seas. More than 40% of the seagrass beds in the Swan Lake area have been restored, and more than 8,000 whooper swans come to winter each year.
It is not easy to "grow grass" on the seabed, and many people ask Zhang Peidong: "16 years, what do you rely on to persevere?" ”
Zhang Peidong said: "Isn't it the reason why we insist on taking root and growing grass, bringing vitality and hope to the sea? ”
Source: People's Daily