A method for constructing a sargassum field based on rhizoid vegetative propagation

Abstract

The present invention discloses a method for constructing a sargassum field based on rhizoid vegetative propagation, comprising the following steps: (1) fabricating artificial reefs and, during the vigorous growth period of sargassum, placing the artificial reefs in a natural sargassum field serving as a cultivation sea area for soaking; (2) after soaking the artificial reefs for 1 month, performing a treatment of cutting off the receptacles on the natural sargassum in the cultivation sea area; arranging the soaked artificial reefs around the rhizoids of the sargassum with the receptacles cut off, keeping them close to the rhizoids; (3) cultivating the artificial reefs in the cultivation sea area to enable the rhizoids of sargassum to attach to the surface of the artificial reefs and grow, and regenerating new seedlings through vegetative propagation; when the coverage of the rhizoids of sargassum on the upper surface of the artificial reefs is similar to the coverage of the rhizoids of natural sargassum, transplanting the artificial reefs to the target restoration sea area. This method can enable the rhizoids of sargassum to attach to and grow on the artificial reefs, and ensure the stable reproduction of the sargassum population in the target restoration sea area.

Description

Technical Field

[0001] The present invention belongs to the technical field of restoring the marine ecological environment, and particularly relates to a method for constructing a sargassum bed based on vegetative propagation of rhizoids. Background Art

[0002] The sargassum bed is a typical nearshore ecosystem supported by large seaweeds of the genus Sargassum, which is widely distributed in warm and temperate waters. It has unique functions of creating marine habitats and purifying water quality, and is a stabilizer and restorer of the marine ecosystem. However, due to global climate change and disorderly and excessive human development activities, the global natural sargassum beds have been experiencing severe exhaustion and degradation since the 1960s. Therefore, in order to prevent the "desertification" of the nearshore area, the restoration of the sargassum bed is extremely urgent. At present, the methods for restoring sargassum beds at home and abroad mainly involve constructing artificial algal beds, among which transplanting and cultivating natural sargassum or artificially propagated sargassum are mostly used. However, this not only destroys the natural sargassum resources, but also due to the scouring of sea waves, the attachment rate of seaweed fertilized eggs or seedlings is low, and the transplanted sargassum usually disappears after going through a life history of growth and reproduction, and a natural and stable seaweed bed cannot be formed. Therefore, how to achieve the generation-to-generation reproduction of the sargassum population in the natural sea area is the "bottleneck" problem of the sargassum bed construction technology.

[0003] Moreover, at present, people mainly restore the sargassum bed through sexual reproduction. However, due to the scouring of sea waves in the sea area, whether it is the fertilized eggs released by the sexual reproduction of the parent sargassum or the seedlings artificially sexually propagated, it is very difficult to attach, which is not suitable for the natural sea area environment and cannot fundamentally restore the sargassum bed.

[0004] In addition, Chinese Patent CN103141371 also discloses a method for transplanting and cultivating sargassum on reefs. Specifically, after cutting off the branches and leaves of natural sargassum or artificially sexually propagated sargassum, the rhizoid seedlings of sargassum are transplanted onto natural reefs using a quick-setting cement mortar mixture, and then transplantation and cultivation are carried out. The disadvantages of this method are as follows: 1) It directly transplants natural seedlings or artificially propagated seedlings, which requires sacrificing natural sargassum resources (including the parent sargassum required for artificial sexual propagation is also collected from natural sargassum); 2) Using a quick-setting cement mortar mixture for fixation is likely to bury the rhizoids and seedlings of sargassum, which is not conducive to the survival and growth of the rhizoids and seedlings of sargassum; 3) In addition, in the low-tide area, the scouring of the tide is frequent, which also affects the setting effect of the quick-setting cement mortar mixture. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for constructing a sargassum bed based on vegetative propagation of rhizoids, which can promote the attachment and growth of the rhizoids of sargassum on artificial algal reefs and ensure the stable reproduction of the sargassum population in the target restoration sea area.

[0006] The object of the present invention is achieved by the following solutions:

[0007] A method for constructing a Sargassum field based on vegetative propagation of rhizoids, comprising the following steps:

[0008] (1) Fabricate artificial reefs and, during the vigorous growth period of Sargassum (usually from March to April) and during spring tides, place the artificial reefs in a natural Sargassum field serving as a cultivation sea area for soaking.

[0009] (2) After soaking the artificial reefs for 1 month, perform the treatment of cutting off the receptacles on the natural Sargassum in the cultivation sea area to end its sexual reproduction.

[0010] Place the soaked artificial reefs around the rhizoids of the Sargassum with the receptacles cut off, keeping them close to the rhizoids of the Sargassum with the receptacles cut off, so as to facilitate the extension growth and attachment of the rhizoids of the Sargassum to the surface of the artificial reefs.

[0011] (3) Cultivate the artificial reefs in the cultivation sea area to enable the rhizoids of the Sargassum to grow attached to the surface of the artificial reefs and regenerate new seedlings through vegetative propagation.

[0012] Observe the attachment and growth of the rhizoids of the Sargassum on the upper surface of the artificial reefs, and estimate the coverage of the rhizoids of the Sargassum on the upper surface of the artificial reefs; when the coverage of the rhizoids of the Sargassum on the upper surface of the artificial reefs is similar to the coverage of the rhizoids of the natural Sargassum, the artificial reefs can be transplanted to the target restoration sea area to construct a natural and stable Sargassum field.

[0013] In step (1), during the vigorous growth period of Sargassum (usually from March to April) and during spring tides, place the artificial reefs in the cultivation sea area. At this time, the spring tide ebbs low, and the lowest tide is during the day, which is convenient for transporting the artificial reefs to the cultivation sea area and removing the alkaline substances in the artificial reefs through seawater soaking.

[0014] Furthermore, in step (1), place the artificial reefs at a position more than 10 m away from the growth area of the natural Sargassum and soak them with seawater.

[0015] The artificial reefs are rectangular plate bodies cast from cement, yellow sand, sand and water, and oyster shells and stones are inlaid on their upper surfaces to make their upper surfaces uneven to help the rhizoids of the Sargassum attach; the upper surface is the side facing up when the artificial reefs are placed in the sea area. Preferably, the length, width and height of the artificial reefs are 25 - 30 cm, 15 - 20 cm and 3 - 5 cm respectively.

[0016] The cultivation sea area is a natural Sargassum field located in the rocky intertidal zone, with a relatively flat terrain, good growth of Sargassum and well-developed rhizoids.

[0017] In step (2), after the artificial algal reef has been soaked for one month, which coincides with the sexual reproduction period of Sargassum, use scissors to cut off the receptacles of Sargassum to promote the growth of the rhizoids of Sargassum; the number of Sargassum with receptacles cut off is ≤ the number of artificial algal reefs.

[0018] Under normal circumstances, after a natural Sargassum completes its life cycle, its stems, leaves, and rhizoids will all rot and fall off into the seawater. Moreover, the effective reproduction method of natural Sargassum is rhizoid vegetative reproduction. Therefore, cutting off the receptacles of natural Sargassum and retaining the rhizoids will not damage the natural Sargassum resources. Additionally, by August, a complete life cycle of Sargassum will end. Therefore, in the present invention, cutting off the receptacles of Sargassum to prematurely end the sexual reproduction period of Sargassum can promote the growth of rhizoids and extend its vegetative reproduction period, thereby increasing the attachment area of rhizoids on the artificial algal reef and also achieving the proliferation of Sargassum resources.

[0019] The receptacle mentioned above is the reproductive organ of Sargassum that discharges sperm or eggs during sexual reproduction.

[0020] In step (2), the work of deploying the artificial algal reef can be carried out simultaneously with the treatment of cutting off the receptacles. Specifically, place 1 - 4 artificial algal reefs around the rhizoids of Sargassum with receptacles cut off that are joined into blocks, and use the nearby natural Sargassum reefs to fix the position of the artificial algal reef. And due to the influence of tidal impact, the artificial algal reef may shift. Utilize the spring tide period in the subsequent 2 - 3 days to continuously adjust the position of the artificial algal reef so that it is firmly stuck between the natural Sargassum reefs and remains close to the rhizoids of Sargassum with receptacles cut off.

[0021] In step (3), the equal - division grid method is used to estimate the coverage of Sargassum rhizoids on the upper surface of the artificial algal reef. The equal - division grid method is specifically as follows: Divide the length and width of the upper surface of the artificial algal reef into a and b equal parts respectively, with a total of a * b identical rectangular or square grids. Then, visually estimate the number of grids with rhizoids attached and calculate the percentage of the total number of grids it occupies, which is the coverage of Sargassum rhizoids on the upper surface of the artificial algal reef. Among them, when the attached area of the rhizoid is less than half of the grid, it is calculated as 1 / 2 grid; when it is equal to or more than half of the grid, it is calculated as a full grid.

[0022] In step (3), the estimation method for the coverage of natural Sargassum rhizoids is as follows: Select multiple approximately flat natural reefs, draw rectangular sample frames with dimensions similar to those of the artificial algal reef, and also use the equal - division grid method to estimate the coverage of natural Sargassum rhizoids, and then calculate the average coverage.

[0023] In step (3), the cultivation time should at least experience three Sargassum life cycles.

[0024] Furthermore, after artificial algal reefs are arranged around the rhizoids of the present invention, the vegetative propagation period of the rhizoids in the first life history of Sargassum begins. The rhizoids of Sargassum with the receptacles cut off grow rapidly and extend to attach to the upper surface of the artificial algal reefs close to the rhizoids. New seedlings are regenerated through vegetative propagation. At this time, most of the rhizoids attached to the upper surface of the artificial algal reefs are located on the side close to the rhizoids of the Sargassum with the receptacles cut off. At the beginning of the vegetative propagation period of the rhizoids in the second life history of Sargassum, according to the attachment situation of the Sargassum rhizoids on the upper surface of the artificial algal reefs, the receptacles of natural Sargassum are cut off, and the side of the artificial algal reef without attached rhizoids is moved to the rhizoids of the Sargassum with the receptacles cut off to increase the attachment area of the rhizoids on the artificial algal reefs. By the vegetative propagation period of the rhizoids in the third life history of Sargassum, continuously observe the attachment situation of the Sargassum rhizoids on the artificial algal reefs, and estimate the coverage of the Sargassum rhizoids on the upper surface of the artificial algal reefs according to the equal division method. When the coverage of the rhizoids is similar to that of the natural Sargassum rhizoids, the artificial algal reef can be transplanted to the target restoration sea area. Otherwise, continue to cultivate the artificial algal reef through the receptacle cutting treatment.

[0025] Compared with the prior art, the present invention has the following beneficial effects.

[0026] (1) The present invention utilizes the time law of the natural population reproduction of Sargassum. During the sexual reproduction period of Sargassum, by cutting off the receptacles, the growth of the rhizoids is promoted and the vegetative propagation period of the rhizoids is extended, the attachment area of the Sargassum rhizoids on the artificial algal reefs is increased, the Sargassum resources are multiplied, and a natural and stable Sargassum field is constructed.

[0027] In addition, under normal circumstances, after Sargassum completes one life history, its stems, leaves and rhizoids all rot and fall off into the sea water. Under suitable conditions, new seedlings grow again at the original rhizoid attachment site and enter the next life history. Therefore, the present invention cuts off the receptacles of natural Sargassum in the natural Sargassum field and regenerates new seedlings through vegetative propagation, which not only does not damage the natural Sargassum resources, but also multiplies the Sargassum resources by extending the rhizoids to the artificial algal reefs, providing a rich seedling source for the target restoration sea area.

[0028] (2) The Sargassum rhizoids treated by the method of the present invention are well-developed and firmly attached to the artificial algal reefs, adapting to the impact of large waves in the natural environment. The transplanted Sargassum can grow and reproduce normally in the target restoration sea area, and there is no significant difference in the plant height and rhizoid coverage between the transplanted Sargassum and the natural Sargassum.

[0029] (3) The present invention determines that when the coverage of the Sargassum rhizoids on the upper surface of the artificial algal reef is similar to that of the natural Sargassum rhizoids, the artificial algal reef is transplanted to the target restoration sea area to ensure that the transplanted Sargassum can grow and reproduce normally. Specifically, the artificial algal reef of the present invention has undergone the test of at least three Sargassum life histories to ensure that after transplantation, there is no significant difference in the plant height and rhizoid coverage of the Sargassum on the artificial algal reef and the natural Sargassum.

[0030] (4) The present invention estimates the coverage of the holdfasts of Sargassum by using the equal - division grid method. This method for estimating the holdfast coverage can be easily implemented on - site, has high accuracy, and is convenient for quickly making a transplantation operation plan.

[0031] (5) The present invention cultivates artificial algal reefs in the natural environment. Its surface not only adheres to the target seaweeds but also adheres to the biological species of the natural Sargassum field, and a Sargassum field ecological community has been initially formed.

[0032] (6) Except that the operation of making artificial algal reefs in the present invention occurs on land, other implementation links are all carried out in the rocky intertidal zone sea area. Compared with the existing transplantation and cultivation of artificial seedlings, it does not require places such as nursery ponds and indoor seaweed cultivation work, does not require daily management, does not occupy land, has low labor intensity, saves costs, is simple to operate, has a high success rate, and is easy to promote. Description of the Drawings

[0033] Figure 1 is a flowchart of the method for constructing a Sargassum field based on the vegetative propagation of holdfasts of the present invention;

[0034] Figure 2 is a picture of the artificial algal reef cultivated by the present invention (① and ② are the attached holdfasts, ③ and ④ are the attached Sargassum plants, and ⑤ is the attached sea urchin); [[ID=2`0]]

[0035] Figure 3 is a graph showing the change trend of the plant heights of the transplanted Sargassum and natural Sargassum of the present invention;

[0036] Figure 4 is a graph showing the change trend of the holdfast coverages of the transplanted Sargassum and natural Sargassum of the present invention. Detailed Embodiments [[ID=`30]]

[0037] The method of the present invention is applicable to constructing large - scale Sargassum fields of Sargassum species with well - developed holdfasts, such as Sargassum hemiphyllum, Sargassum natans, Sargassum henslowianum, Sargassum integerrimum, etc.; the following further illustrates the present invention through specific embodiments of constructing a Sargassum hemiphyllum field.

[0038] Refer to Figure 1 the process, construct a Sargassum hemiphyllum field, including the following steps:

[0039] 1) Fabrication of artificial algal reefs:

[0040] Mix cement, yellow sand, sand, and water, and pour them into a cement rectangular plate with a length * width * height of 30 cm * 20 cm * 3 cm. Before the cement solidifies, lay oyster shells, stones, etc. on the upper surface of the artificial algal reef to make its upper surface uneven and increase the roughness of the upper surface; inlay an acrylic sign on the upper - right corner of the upper surface of the artificial algal reef for easy later search and observation.

[0041] 2) Selection of cultivation sea areas:

[0042] A natural half-leaf Sargassum field located in the rocky intertidal zone was selected as the cultivation sea area. The terrain there is relatively flat, and the half-leaf Sargassum grows well with well-developed rhizomes.

[0043] 3) Immersion of artificial algae reefs:

[0044] During the peak growth period of half-leaf sargassum (March-April), choose the high tide period to transport the artificial algae reef to the cultivation sea area and place it 10-20m away from the half-leaf sargassum growth area. Use seawater to soak for about 1 month to remove the alkaline substances in the artificial algae reef.

[0045] 4) Treatment of Sargassum stalk shearing

[0046] After the artificial algae reef is immersed for one month, which is the sexual reproduction period of half-leaf Sargassum (April-May), the reproductive stalks of natural half-leaf Sargassum in the cultivation area are cut off, and the number of half-leaf Sargassum with the reproductive stalks cut off is ≤ the number of artificial algae reefs;

[0047] The effective reproduction method of Sargassum semi-leaf in the intertidal zone of rocky reefs is rhizoid vegetative reproduction. Cutting off the reproductive receptacle of Sargassum semi-leaf and retaining the rhizoid will not damage the natural Sargassum semi-leaf resources. Moreover, when August comes, a complete life cycle of Sargassum semi-leaf will end. Therefore, cutting off the reproductive receptacle of Sargassum semi-leaf can end the sexual reproduction period of Sargassum semi-leaf in advance, promote the growth of rhizoids and extend its vegetative reproduction period, and expand the attachment area of rhizoids on artificial algae reefs.

[0048] 5) Deployment of artificial algal reefs

[0049] While the reproductive stalks are being cut, 1-4 soaked artificial algae reefs are placed around the rhizomes of several half-leaf Sargassum plants that have had their reproductive stalks cut off, and the position of the artificial algae reefs is fixed using nearby natural Sargassum reefs. Due to the influence of tidal impact, the position of the artificial algae reef may shift. During the subsequent 2-3 days of high tide, the position of the artificial algae reef is continuously adjusted to ensure that it is firmly embedded between the natural reefs and remains close to the rhizomes of the half-leaf Sargassum.

[0050] 6) Cultivation and transplantation of artificial algal reefs

[0051] After the artificial algae reef was laid, the rhizoid vegetative reproduction period of the first half-leaf Sargassum with its reproductive stalk cut off was from May to July, while May to June was the decline period of the half-leaf Sargassum with its reproductive stalk not cut off, and June to July was the rhizoid vegetative reproduction period of the half-leaf Sargassum with its reproductive stalk not cut off. That is, the half-leaf Sargassum with its reproductive stalk cut off had a vegetative reproduction period one month longer than the half-leaf Sargassum with its reproductive stalk not cut off.

[0052] During the cultivation of artificial algal reefs, the rhizoids of Sargassum hemiphyllum with the receptacles cut off grow rapidly, extend and attach to the upper surface of the artificial algal reefs close to the rhizoids, and new seedlings are regenerated through vegetative propagation of the rhizoids. At this time, more of the rhizoids attached to the upper surface of the artificial algal reefs are located on the side close to the rhizoids of Sargassum hemiphyllum with the receptacles cut off.

[0053] During the vegetative propagation period of the rhizoids in the second life history of Sargassum hemiphyllum with the receptacles cut off, according to the attachment situation of the rhizoids of Sargassum hemiphyllum on the upper surface of the artificial algal reefs, the receptacles of natural Sargassum hemiphyllum are cut off again, and the side of the artificial algal reef without attached rhizoids is moved to the rhizoids of Sargassum hemiphyllum with the receptacles cut off (repeat the operation in step 5 above), and continue to cultivate to increase the attachment area of the rhizoids on the artificial algal reefs.

[0054] During the vegetative propagation period of the rhizoids in the third life history of Sargassum with the receptacles cut off, continuously observe the attachment and growth of the rhizoids of Sargassum hemiphyllum on the artificial algal reefs; according to the equal - division grid method, visually divide the length of the upper surface of the artificial algal reef into 5 equal parts with 6 cm each, and the width into 4 equal parts with 5 cm each, for a total of 20 identical rectangular grids. The percentage of the number of grids with attached rhizoids in the total number of grids is the coverage of the rhizoids of Sargassum hemiphyllum on the upper surface of the artificial algal reef.

[0055] After estimation, after three Sargassum life histories of cultivating artificial algal reefs, as a control, the attachment area of the rhizoids of Sargassum hemiphyllum without the receptacles cut off accounts for 1 / 2 grid, while the attachment area of the rhizoids of Sargassum hemiphyllum with the receptacles cut off accounts for 3 grids. That is, their coverages are approximately 3% and 15% respectively, indicating that cutting off the receptacles can significantly promote the growth and attachment of the rhizoids of Sargassum hemiphyllum.

[0056] Using the equal - division grid method to estimate the coverage of the rhizoids of natural Sargassum on multiple natural algal reefs, the average value is about 20%.

[0057] When the coverage of the rhizoids of Sargassum hemiphyllum on the upper surface of the artificial algal reef is similar to that of natural Sargassum hemiphyllum, such as when the above - mentioned coverage reaches 15% (since the coverage of the rhizoids of natural Sargassum is the average value, as long as the coverage of the rhizoids of Sargassum hemiphyllum with the receptacles cut off differs from it by within 10%, it can be considered that their coverages are similar), the artificial algal reef can be transplanted to the target restoration sea area to construct a Sargassum hemiphyllum field; while the artificial algal reefs with a lower coverage can be continuously cultivated through the receptacle - cutting treatment in this life history and the next Sargassum hemiphyllum life history.

[0058] 7) Evaluation of the effect of transplanting Sargassum

[0059] From March to August of the following year, when the tide recedes to the spring low - tide line, in the growth area of Sargassum hemiphyllum in the target restoration sea area and the growth area of natural Sargassum hemiphyllum in the cultivation sea area, randomly set 3 quadrats of 25 cm×25 cm, and measure the plant height and rhizoid coverage of Sargassum hemiphyllum in the quadrats. The results are shown in Figure 3and Figure 4 。

[0060] Figure 3 The results show that both the transplanted Sargassum hemiphyllum and the natural Sargassum hemiphyllum grow taller over time, with a significant increase in plant height in April, reaching the maximum in May, and no significant difference in plant height between April and May. However, in June, the stems and leaves of the Sargassum hemiphyllum plants rot and break off, resulting in a significant decrease in plant height. In July, almost all the plants have fallen off, leaving only some short Sargassum seedlings growing from the remaining rhizoids. In August, the Sargassum seedlings on the rhizoids rot and disappear.

[0061] Figure 4 The results show that the coverage of the rhizoids of the transplanted Sargassum hemiphyllum and the natural Sargassum hemiphyllum increases significantly in April. There is no significant difference between April and June, but in July, the rhizoids of the Sargassum hemiphyllum begin to rot, and their coverage decreases significantly. In August, the rhizoids rot and disappear, entering the resting stage, and one life cycle ends. In winter, new seedlings germinate again from the rhizoids of the Sargassum hemiphyllum, starting the next life cycle.

[0062] The results show that there is no significant difference in plant height and rhizoid coverage between the transplanted Sargassum hemiphyllum of the present invention and the natural Sargassum hemiphyllum, indicating that the transplanted Sargassum hemiphyllum can grow and reproduce smoothly in the target restoration sea area like the natural Sargassum hemiphyllum, forming a real Sargassum hemiphyllum field.

[0063] The present invention can be outlined in other specific forms that do not violate the spirit or main features of the present invention. The above embodiments of the present invention should only be considered as illustrative rather than restrictive. Therefore, any minor modifications, equivalent changes, and modifications made to the above embodiments based on the essential technology of the present invention are all within the scope of the technical solution of the present invention.

Claims

1. A method for constructing a sargassum field based on rhizoid vegetative propagation, characterized in that, It includes the following steps: (1) Fabricate artificial algal reefs, and during the vigorous growth period of Sargassum, immerse the artificial algal reefs in a natural Sargassum field as the cultivation sea area; the cultivation sea area is a natural Sargassum field located in the rocky intertidal zone, and the Sargassum in it grows well and has well-developed rhizoids; After the artificial algal reefs are immersed for 1 month, when it is the sexual reproduction period of Sargassum, perform the treatment of cutting off the reproductive receptacles on the natural Sargassum in the cultivation sea area to end its sexual reproduction and promote the growth of the rhizoids of Sargassum; among them, the number of Sargassum with the reproductive receptacles cut off is ≤ the number of artificial algal reefs; Lay the immersed artificial algal reefs around the rhizoids of the Sargassum with the reproductive receptacles cut off, and keep them close to the rhizoids of the Sargassum with the reproductive receptacles cut off, so as to facilitate the extension and attachment of the rhizoids of Sargassum to the surface of the artificial algal reefs; (3) Cultivate the artificial algal reefs in the cultivation sea area to make the rhizoids of Sargassum attach to the surface of the artificial algal reefs and regenerate new seedlings through vegetative propagation; Observe the attachment and growth situation of the rhizoids of Sargassum on the upper surface of the artificial algal reefs, and estimate the coverage of the rhizoids of Sargassum on the upper surface of the artificial algal reefs; when the coverage of the rhizoids of Sargassum on the upper surface of the artificial algal reefs is similar to the coverage of the rhizoids of natural Sargassum, transplant the artificial algal reefs to the target restoration sea area to construct a Sargassum field.

2. The method for constructing a sargassum bed according to claim 1, characterized in that, in In step (2), the work of laying the artificial algal reefs is as follows: place 1 - 4 artificial algal reefs around the rhizoids of the Sargassum with the reproductive receptacles cut off that are joined into blocks, and use the nearby natural Sargassum reefs to fix the positions of the artificial algal reefs; utilize the spring tides in the subsequent 2 - 3 days to continuously adjust the positions of the artificial algal reefs to make them firmly stuck between the natural Sargassum reefs and keep close to the rhizoids of the Sargassum with the reproductive receptacles cut off.

3. The method for constructing a sargassum bed according to claim 2, characterized in that, In step (3), the cultivation time lasts for at least three Sargassum life histories.

4. The method for constructing a sargassum bed according to claim 3, wherein After laying the artificial algal reefs around the rhizoids, the vegetative propagation period of the rhizoids in the first Sargassum life history begins. The rhizoids of the Sargassum with the reproductive receptacles cut off grow rapidly and extend and attach to the upper surface of the artificial algal reefs close to the rhizoids, and new seedlings are regenerated through vegetative propagation. At this time, most of the rhizoids attached to the upper surface of the artificial algal reefs are on the side close to the rhizoids of the Sargassum with the reproductive receptacles cut off; when the vegetative propagation period of the rhizoids in the second Sargassum life history begins, according to the attachment situation of the rhizoids of Sargassum on the upper surface of the artificial algal reefs, perform the treatment of cutting off the reproductive receptacles on the natural Sargassum, and move the side of the artificial algal reefs without attached rhizoids to the rhizoids of the Sargassum with the reproductive receptacles cut off to increase the attachment area of the rhizoids on the artificial algal reefs; by the vegetative propagation period of the rhizoids in the third Sargassum life history, continuously observe the attachment situation of the rhizoids of Sargassum on the artificial algal reefs, and estimate the coverage of the rhizoids of Sargassum on the upper surface of the artificial algal reefs according to the equal - division grid method; when the coverage of the rhizoids is similar to that of the natural Sargassum rhizoids, transplant the artificial algal reefs to the target restoration sea area.

5. The method for constructing a sargassum bed according to any one of claims 1 to 4, characterized in that, in In step (3), the coverage of the holdfasts of Sargassum on the upper surface of the artificial reef is estimated by the equal-division grid method; specifically, the equal-division grid method is as follows: the length and width of the upper surface of the artificial reef are respectively divided into a and b equal parts, with a total of a*b identical rectangular or square grids, and then the number of grids with holdfasts attached is visually estimated, and the percentage of the total number of grids it accounts for is calculated, which is the coverage of the holdfasts of Sargassum on the upper surface of the artificial reef; among them, when the attachment area of the holdfasts is less than half of the grid, it is calculated as 1 / 2 grid, and when it is equal to or more than half of the grid, it is calculated as a full grid.

6. The method for constructing a sargassum bed according to claim 5, characterized in that, in In step (3), the method for estimating the coverage of the holdfasts of natural Sargassum is as follows: multiple approximately flat natural reefs are selected, rectangular sample frames with dimensions similar to those of the artificial reef are marked out, and the equal-division grid method is also used to estimate the coverage of the holdfasts of natural Sargassum, and then the average coverage is calculated.

7. The method for constructing a sargassum bed according to claim 1, wherein The artificial reef is a rectangular plate body formed by pouring cement, yellow sand, sand and water, and oyster shells and stones are inlaid on its upper surface to make its upper surface uneven to help the attachment of the holdfasts of Sargassum.

8. The method for constructing a sargassum bed according to claim 1, wherein In step (1), the artificial reef is placed at a position more than 10 m away from the growth area of natural Sargassum and soaked with seawater.

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