A method for intertidal zone seagrass and bottom buried type shellfish collaborative restoration based on sediment-species matching in beibu gulf

Abstract

The present application provides a kind of based on sediment-species matching Beibuwan intertidal zone seagrass and bottom buried type shellfish synergistic repair method, belong to the coastal wetland ecological restoration technical field.The method provided by the present application transplants seagrass and sows bottom buried type shellfish seedling in the intertidal zone to be repaired.The present application focuses on the short board of seagrass repair technology, and innovatively proposes the concept of seagrass bed animal and plant synergistic repair, first surveys the sediment type (argillaceous, silty or sandy) of the intertidal zone to be repaired, matches suitable native seagrass (Japanese eel grass, ovate salt-loving grass, Beck salt-loving grass) and bottom buried type shellfish (green mussels, mangrove clams, etc.), adopts the transplanting and sowing sequence of seagrass first and shellfish later, combines with the mechanism of enclosure netting protection and round catching and seedling replenishment, realizes the mutual benefit and symbiosis of seagrass and shellfish, has ecological and economic benefits, effectively alleviates the problems of poor seagrass repair effect and insufficient protection and management, and is suitable for the ecological restoration of intertidal zone with different sediment types in Beibuwan.

Description

Technical Field

[0001] This application belongs to the field of coastal wetland ecological restoration technology, specifically involving a method for the synergistic restoration of intertidal seagrass and bottom-buried shellfish in Beibu Gulf based on sediment-species matching. Background Technology

[0002] Intertidal seagrass beds possess transitional land-sea properties, purifying water, sequestering and storing carbon, mitigating waves and protecting shorelines, resisting storm surges and coastal erosion, and also retaining land-based pollutants, degrading nitrogen and phosphorus pollutants, and mitigating nearshore eutrophication and red tide risks. However, due to land reclamation, aquaculture, and pollution discharge, intertidal zones are experiencing shrinking mudflats, habitat fragmentation, and a sharp decline in biodiversity. The protection and restoration of intertidal blue carbon ecosystems is a crucial component of my country's territorial ecological protection and restoration efforts and climate change mitigation measures. The Beibu Gulf region is one of the main areas for seagrass restoration.

[0003] my country faces challenges in seagrass conservation and restoration, including insufficient regional coordination. For instance, most standards focus primarily on vegetation restoration, with relatively little emphasis on overall ecosystem restoration; and biodiversity baseline surveys and monitoring are inadequate. Experts both domestically and internationally have called for coastal wetland ecological restoration to expand from vegetation restoration to the overall structure and function of the wetland ecosystem, incorporating animal restoration into the restoration objectives, and further improving the coastal ecological restoration and evaluation standards system. However, existing seagrass bed ecosystem restoration systems lack reports on animal restoration, and without considering the habitat characteristics of different sediment types and precise matching schemes with native species, interspecific competition may occur in some combinations, inhibiting seagrass growth. Therefore, key technologies for synergistic restoration of plants and animals are urgently needed to improve the overall function of seagrass beds, balancing ecological, economic, and social benefits, and promoting advancements in seagrass bed restoration technology. Summary of the Invention

[0004] The purpose of this invention is to provide a method for the synergistic restoration of intertidal seagrass and bottom-buried shellfish in Beibu Gulf based on sediment-species matching. This invention focuses on the shortcomings of seagrass restoration technology and innovatively proposes the concept of synergistic restoration of seagrass beds by flora and fauna. By incorporating bottom-buried shellfish, it not only promotes the growth of seagrass but also allows for the harvesting of shellfish to obtain certain economic value, greatly improving the initiative of intertidal restoration.

[0005] This invention provides a method for the co-remediation of intertidal seagrass and bottom-buried mollusks in the Beibu Gulf based on sediment-species matching, comprising the following steps: S1 Habitat Survey: Determine the sediment types in the intertidal zone to be restored; S2 Species Matching: Select suitable native seagrass species and bottom-dwelling mollusks based on sediment type; S3 Seagrass Transplantation: Transplanting seagrass to the intertidal zone to be restored; S4 Shellfish Seeding: After seagrass transplantation, bottom-buried shellfish seedlings are seeded; S5 Management and Harvesting: Set up protective nets to prevent shellfish seedlings from escaping; harvest the shellfish after they reach marketable size and the seaweed has completed a growth cycle.

[0006] Preferably, the bottom-buried shellfish includes at least one of the following: blue clam, mangrove clam, hard clam, lyre clam, hairy clam, Manila clam, hard clam and razor clam.

[0007] Preferably, the sediment types in the intertidal zone to be restored include at least one type: muddy sediments, silty sediments, and sandy sediments.

[0008] Preferably, the seaweed includes at least one of the following: Japanese eelgrass, ovoid halophila, and becker halophila.

[0009] Preferably, when transplanting the Japanese eelgrass, the intertidal zone to be restored is a muddy sediment, and suitable bottom-buried shellfish include blue clam or mangrove clam; the intertidal zone to be restored is a sandy sediment, and suitable bottom-buried shellfish include at least one of the following: blue clam, hard clam, Manila clam, hard clam, beautiful hard clam and razor clam.

[0010] Preferably, when transplanting the ovary-leaved halophilic grass, the intertidal zone to be restored is composed of silty sediments, and suitable bottom-dwelling shellfish include at least one of the following: blue clam, Manila clam, hard clam, lynx clam, and blood clam; the intertidal zone to be restored is composed of sandy sediments, and suitable bottom-dwelling shellfish include at least one of the following: hard clam, Manila clam, hard clam, lynx clam, and razor clam.

[0011] Preferably, when transplanting the *Haliotis diversicolor*, the intertidal zone to be restored is muddy sediment, and suitable bottom-buried shellfish include *Clams maculatus* or *Clams spp.*; the intertidal zone to be restored is silty or sandy sediment, and suitable bottom-buried shellfish include at least one of the following: *Clams maculatus*, *Clams floribunda*, *Clams floribunda*, and *Clams spp.*

[0012] Preferably, the seaweed transplantation adopts the grass block transplantation method, with each grass block having a size of 10 cm × 10 cm to 15 cm × 15 cm; the transplantation density is 0.5 m × 0.5 m to 1 m × 1 m; The timing for seagrass transplantation includes autumn to winter.

[0013] Preferably, the bottom-buried shellfish are sown after seagrass transplantation is completed; The specifications for the bottom-buried shellfish larvae are 110-130 individuals / kg; The sowing density of the bottom-buried shellfish larvae is 15-40 per m². 2 .

[0014] Preferably, the mesh size of the enclosure net is smaller than that of the bottom-buried shellfish seedlings sown; the method of harvesting shellfish is to pick the larger ones and leave the smaller ones, while simultaneously replenishing the bottom-buried shellfish seedlings.

[0015] This invention provides a method for the synergistic restoration of intertidal seagrass and bottom-buried shellfish in the Beibu Gulf based on sediment-species matching. According to the determined type of sediment in the intertidal zone to be restored, seagrass is transplanted, followed by the sowing of bottom-buried shellfish larvae. A protective net is set up to prevent the larvae from escaping. Once the shellfish reach marketable size and the seagrass completes one growth cycle, the mature shellfish are harvested. This invention is based on the principle of stratified utilization through overlapping ecological niches of flora and fauna. While restoring the growth of intertidal seagrass, the sowing of bottom-buried shellfish larvae is added. Suitable bottom-buried shellfish can effectively promote seagrass growth, increase seagrass biomass and resilience. Simultaneously, the construction of seagrass beds provides a relatively stable living environment for bottom-buried shellfish, thereby promoting their growth. After harvesting, it also increases the income of local fishermen, further promoting the restoration of the intertidal zone. It is evident that the synergistic restoration of seagrass and bottom-buried shellfish can not only increase the carbon sink capacity of the coastal blue carbon ecosystem and the biodiversity of the intertidal zone, but also maintain the livelihood needs of coastal fishermen, effectively alleviating the sharp contradiction between the protection and utilization of intertidal mudflats.

[0016] The method provided by this invention further specifies the types of bottom-buried shellfish, seagrass, and sediments. Experiments show that the combination of bottom-buried shellfish species, seagrass types, and sediment types all affect the remediation effect. For example, when Japanese eelgrass is remediated together with different shellfish, compared with the seagrass-only remediation group, mangrove clams and hard clams can significantly increase seagrass coverage, while Manila clams and hard clams have little effect on promoting seagrass coverage. At the same time, mangrove clams and hard clams growing in seagrass beds formed by Japanese eelgrass can also yield a large quantity of high-quality shellfish products. Attached Figure Description

[0017] Figure 1 Photos of intertidal zone restoration using Japanese eelgrass combined with mangrove clams; Figure 2 Photos of the intertidal zone restoration project using Japanese eelgrass combined with Manila clams; Figure 3 Photos of the intertidal zone restoration project using Japanese eelgrass combined with blue clam; Figure 4 Photos of the intertidal zone restoration project using Japanese eelgrass combined with hard clam. Figure 5 A schematic diagram illustrating the experimental distribution of Japanese eelgrass combined with bottom-buried mollusks; Figure 6 Image of shellfish sown during the co-remediation experiment of Halophyta ovata and shellfish; Figure 7Photos of the intertidal zone restoration project using Halophytum ovatum and shellfish; Figure 8 Photos of a seagrass bed planted with Haworthia cooperi for shellfish farming. Figure 9 The clam is harvested by combining the growth of *Salmonella spp.* with *Clams spp.* or *Clams spp.*. Detailed Implementation

[0018] This invention provides a method for the co-remediation of intertidal seagrass and bottom-buried mollusks in the Beibu Gulf based on sediment-species matching, comprising the following steps: S1 Habitat Survey: Determine the sediment types in the intertidal zone to be restored; S2 Species Matching: Select suitable native seagrass species and bottom-dwelling mollusks based on sediment type; S3 Seagrass Transplantation: Transplanting seagrass to the intertidal zone to be restored; S4 Shellfish Seeding: After seagrass transplantation, bottom-buried shellfish seedlings are seeded; S5 Management and Harvesting: Set up protective nets to prevent shellfish seedlings from escaping; harvest the shellfish after they reach marketable size and the seaweed has completed a growth cycle.

[0019] In this invention, the selection of the intertidal zone to be restored is preferably based on standards such as the "Handbook for Ecological Restoration of Seagrass Beds" and "Technical Guidelines for Marine Ecological Restoration Part 4: Ecological Restoration of Seagrass Beds" to determine suitable seagrass restoration habitats.

[0020] In this invention, the selection of bottom-buried shellfish is preferably carried out through benthic animal surveys or field visits, as well as intertidal biological surveys, within the selected restoration habitat to screen out shellfish or specialty shellfish with high economic value and suitable for growth in the corresponding sediments. In the Beibu Gulf region, the sediment types in the intertidal zone to be restored preferably include at least one type: muddy sediments, silty sediments, and sandy sediments. For the Beibu Gulf intertidal zone survey, suitable bottom-buried shellfish preferably include at least one of the following: *Meretrix meretrix*, *Clams maculatus*, *Meretrix dulcis*, *Clams floribunda*, *Clams scabra*, *Clams maculatus*, *Clams ventricosa*, *Clams ventricosa*, and *Clams scabra*. Simultaneously, suitable seagrass species for transplantation preferably include at least one of the following: *Haloxylon ammodendron*, *Haloxylon ovata*, and *Haloxylon beckerii*.

[0021] In this invention, the seagrass transplantation adopts the block transplantation method. The preferred size of each block is 10 cm × 10 cm to 15 cm × 15 cm, or 12 cm × 12 cm. The preferred transplanting density is 0.5 m × 0.5 m to 1 m × 1 m, or 0.6 m × 0.6 m to 0.8 m × 0.8 m, or 0.7 m × 0.7 m. The preferred timing for seagrass transplantation is from autumn to winter, specifically determined according to the growth cycle of the seagrass and shellfish. When sowing bottom-buried shellfish seedlings, avoid placing them on exposed mudflats during periods of high temperature and direct sunlight; they can be placed during high tide or when the tide is about to submerge the mudflats. The preferred size of the bottom-buried shellfish seedlings is 110-130 individuals / kg, or 120 individuals / kg; the preferred sowing density is 15-40 individuals / m². 2 It can be 18~32 pieces / m 2 It can be 20~25 pieces / m 2 .

[0022] In this invention, the types of bottom-buried mollusks to be sown are determined based on the sediment type and the type of seagrass transplanted. The specific combination scheme is as follows: When transplanting the Japanese eelgrass, the intertidal zone to be restored is preferably muddy sediment, and suitable bottom-buried shellfish preferably include blue clam or mangrove clam; if the intertidal zone to be restored is sandy sediment, suitable bottom-buried shellfish preferably include at least one of the following: blue clam, hard clam, Manila clam, hard clam, beautiful hard clam and razor clam.

[0023] When transplanting the ovary-leaved halophilic grass, the intertidal zone to be restored is composed of silty sediments. Suitable bottom-buried shellfish preferably include at least one of the following: hard clam, Manila clam, hard clam, hard clam and blood clam; the intertidal zone to be restored is composed of sandy sediments. Suitable bottom-buried shellfish preferably include at least one of the following: hard clam, Manila clam, hard clam, hard clam and razor clam.

[0024] When transplanting the *Haliotis diversicolor*, the intertidal zone to be restored is preferably muddy sediment, and suitable bottom-buried shellfish include *Clams maculatus* or *Clams mangroves*; if the intertidal zone to be restored is silty or sandy sediment, suitable bottom-buried shellfish preferably include at least one of the following: *Clams maculatus*, *Clams floribunda*, *Clams floribunda*, and *Clams scabra*.

[0025] In this invention, after the bottom-dwelling mollusks are sown, it is preferable to protect the intertidal zone to be restored with a net; the mesh size of the net is preferably smaller than that of the sown bottom-dwelling mollusks. The burial depth of the net is 40-50 cm, and the height of the above-ground portion is preferably 40-50 cm. During the restoration period, maintenance is preferred. The preferred method of maintenance is to regularly patrol the area after low tide to avoid human interference; during the winter and spring seasons when large algae blooms occur, they should be cleaned up promptly.

[0026] In this invention, the harvesting of shellfish is preferably carried out after the seagrass has entered its decline stage. For example, *Haloxylon ammodendron* typically declines in summer and autumn, while *Eriocheir japonica* declines in winter. Harvesting shellfish during the peak seagrass growth season should be avoided as much as possible. If there is a genuine need, strip harvesting should be used within the seagrass bed to avoid full-scale harvesting. This invention does not impose any special restrictions on the harvesting method; conventional fishing methods can be used, such as using low-pressure pulse methods to pinpoint the exact location of the shellfish for precise harvesting, avoiding large-scale digging. The preferred method for harvesting shellfish is to collect larger ones and leave smaller ones, while also supplementing with bottom-buried shellfish larvae.

[0027] In one embodiment of the present invention, through screening and optimization, it was found that not every combination of seagrass and shellfish can achieve a synergistic restoration effect. The present invention uses seagrass coverage and shellfish growth as indicators to evaluate the synergistic restoration effect. For example, in silty sediment environments, when *Erigeron japonica* is combined with different shellfish for restoration, compared with the seagrass-only restoration group (restoration for six months: 26.67%), *Clams rubrotinctum* and *Clams floribunda* significantly promoted seagrass coverage, while *Clams mandarinii* and *Clams floribunda* had little effect on promoting seagrass coverage, only 12.67% and 6.67% respectively. Simultaneously, *Clams rubrotinctum* and *Clams floribunda* growing in seagrass beds formed by *Erigeron japonica* can also yield a large quantity of high-quality shellfish products, specifically a shellfish harvest density of 19-22.3 shellfish / m². 2 Each piece weighs 36-38g.

[0028] Meanwhile, another embodiment of the present invention shows that the method can increase the average number of species, abundance, richness index, diversity index, shellfish abundance, and shellfish biomass of seagrass beds. It is evident that seeding bottom-dwelling shellfish during seagrass bed restoration can effectively increase the biodiversity of the seagrass bed ecosystem.

[0029] The following detailed description, in conjunction with embodiments, illustrates a method for the synergistic restoration of intertidal seagrass and bottom-buried mollusks in the Beibu Gulf based on sediment-species matching, but these descriptions should not be construed as limiting the scope of protection of this invention.

[0030] Example 1 Synergistic Repair Experiment of Japanese Eelgrass and Shellfish 1) Experimental Design A synergistic remediation experiment involving *Erigeron japonicus* and four different mollusks was conducted in Pearl Bay, Fangchenggang, Guangxi (a silty sedimentary environment). A total of 1500 *Erigeron japonicus* blocks were planted at a density of 0.5 × 0.5 m, with each block approximately 15 cm × 15 cm in size. Transplanting took place in autumn. Four bottom-dwelling mollusks were then sown after transplanting. The four mollusks were *Clams maculatus* (…). Geloina erosa ), clam ( Cyclina sinensis ), Philippine clams ( Ruditapes philippinarum ) and clams ( Meretrix meretrixSee details Figures 1-4 A total of 15 5 m × 5 m quadrats were set up (see...). Figure 5 The control group consisted of a single species of Japanese eelgrass. Six months after restoration, seagrass coverage was measured, and shellfish were harvested simultaneously, following the requirements of the Marine Survey Standard GB / T12763.6-2007.

[0031] 2) Experimental Results and Conclusions The results of the co-remediation experiment between Japanese eelgrass and shellfish (Table 1) show that the experimental area is suitable for the proliferation of mangrove clams and blue clams, but not for hard clams and Manila clams. Furthermore, increasing the number of mangrove clams and blue clams effectively improves the seagrass remediation coverage. Therefore, adding suitable bottom-dwelling shellfish to the remediation area is beneficial to both seagrass growth and animal diversity.

[0032] Table 1 Results of the co-remediation experiment between Japanese eelgrass and bottom-dwelling mollusks

[0033] Example 2 A method for the synergistic repair of the intertidal zone by Halophyta ovata and mollusks. 1) Experimental Design In the sandy sedimentary environment of Shatian Peninsula, Hepu County, Beihai City, Guangxi Province, the Halophyta ovata transplantation method was used for the remediation of Halophyta ovata. The planting density was 0.7 × 0.7 m, and the remediation area was approximately 4000 m². 2 One month after planting, five species of shellfish were sown in the restoration area, including *Meretrix meretrix*, *Mackerelia pinnata*, *Meretrix meretrix*, and *Clam simonii*, with each individual weighing approximately 15 g. The total number of these four species released was approximately 2,000. Additionally, 55,000 juvenile *Bacillus simonii*, with a size of approximately 2 mm, were also sown. Figure 6 and Figure 7 ).

[0034] In the restoration area, three survey stations (high, medium, and low) were set up according to the tidal flat elevation. Simultaneously, three bare beach stations (areas without seagrass) were also set up at the corresponding elevations in the control group. Sampling and analysis were conducted according to the requirements of the intertidal biological survey specifications in GB / T12763.6-2007, "Marine Survey Specifications Part 6: Marine Biological Survey". Monthly surveys were conducted eight months after planting, followed by surveys every six months thereafter.

[0035] 2) Experimental Results and Conclusions In terms of macrobenthic abundance, only one seagrass bed had a lower abundance than the bare shoal. The macrobenthic diversity and richness indices of seagrass beds were also mostly higher than those of bare shoals at the surveyed stations. In all monthly surveys, the abundance of shellfish in bare shoals was higher than that in seagrass beds only twice, with the opposite being true in the remaining surveys. The number of times shellfish biomass exceeded half in seagrass beds was greater than in bare shoals. Overall, the average number of species (6.18) and abundance (116.61 ind / m²) in seagrass beds were higher. 2 The abundance index (1.63), diversity index (1.20), and shellfish abundance (37.82 ind / m²) were all significantly higher than the average abundance index (1.20). 2 ) and shellfish biomass (52.84 ind / m 2 Both were greater than the average number of species (4.91) and abundance (64.36 ind / m²) of the average in Guangtan. 2 The abundance index (1.52), diversity index (1.16), and shellfish abundance (13.82 ind / m²) were all significantly higher than the average abundance index (1.16). 2 ) and shellfish biomass (45.89 ind / m 2 See details. Figure 6 and Figure 7 Seeding bottom-dwelling mollusks in the restoration of seagrass beds can effectively increase the biodiversity of the seagrass bed ecosystem.

[0036] Example 3 Clams and mangrove clams are farmed on seagrass beds. In Pearl Bay, Fangchenggang, Guangxi, local residents are cultivating clams and mangrove clams by sowing them in the muddy sediment environment of the seagrass beds on the edge of the mangroves. Figure 8 According to our investigation, shellfish (approximately 10-20g each) are typically sown in early spring at a density of about 30 shellfish per m³. 2 If the seedlings are small, sow them at a higher density. The winter harvest is approximately 600-1000 catties / mu (see...). Figure 9 Meanwhile, the seagrass beds of *Haloxylon ammodendron* are growing well, increasing the diversity of benthic organisms.

[0037] Example 4 In the silty sedimentary environment of Dongwan Bay, Fangchenggang, Guangxi, local residents sowed clams and hard clams onto intertidal seagrass beds of *Halophila ovata* and *Halophila beccidia*. Interviews revealed that they typically sowed shellfish (approximately 10-20g each) in early spring at a density of about 15-30 shellfish per m². 2 The yield is expected to be approximately 400-800 jin per mu in winter.

[0038] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for the co-remediation of intertidal seagrass and bottom-buried mollusks in the Beibu Gulf based on sediment-species matching, characterized in that, Includes the following steps: S1 Habitat Survey: Determine the sediment types in the intertidal zone to be restored; S2 Species Matching: Select suitable native seagrass species and bottom-dwelling mollusks based on sediment type; S3 Seagrass Transplantation: Transplanting seagrass to the intertidal zone to be restored; S4 Shellfish Seeding: After seagrass transplantation, bottom-buried shellfish seedlings are seeded; S5 Management and Harvesting: Set up protective nets to prevent shellfish seedlings from escaping; harvest the shellfish after they reach marketable size and the seaweed has completed a growth cycle.

2. The method according to claim 1, characterized in that, The bottom-dwelling shellfish include at least one of the following: blue clam, mangrove clam, hard clam, hard clam, hairy clam, Manila clam, hard clam and razor clam.

3. The method according to claim 1, characterized in that, The sediment types in the intertidal zone to be restored include at least one type: muddy sediments, silty sediments, and sandy sediments.

4. The method according to claim 1, characterized in that, The seaweed includes at least one of the following: Japanese eelgrass, ovoid halophila, and becker halophila.

5. The method according to claim 4, characterized in that, When transplanting the Japanese eelgrass, if the intertidal zone to be restored is muddy sediment, suitable bottom-buried shellfish include blue clam or mangrove clam; if the intertidal zone to be restored is sandy sediment, suitable bottom-buried shellfish include at least one of the following: blue clam, hard clam, Manila clam, hard clam, beautiful hard clam and razor clam.

6. The method according to claim 4, characterized in that, When transplanting the ovary-leaved halophilic grass, the intertidal zone to be restored is composed of silty sediments, and suitable bottom-buried shellfish include at least one of the following: hard clam, hard clam, hard clam and hairy clam; the intertidal zone to be restored is composed of sandy sediments, and suitable bottom-buried shellfish include at least one of the following: hard clam, Manila clam, hard clam, hard clam and razor clam.

7. The method according to claim 4, characterized in that, When transplanting the aforementioned Haworthia cooperi, if the intertidal zone to be restored is muddy sediment, suitable bottom-buried shellfish include blue clam or mangrove clam; if the intertidal zone to be restored is silty or sandy sediment, suitable bottom-buried shellfish include at least one of the following: blue clam, hard clam, hard clam and blood clam.

8. The method according to any one of claims 1 to 7, characterized in that, The seagrass transplantation adopts the grass block transplantation method; each grass block is 10 cm×10 cm~15 cm×15 cm in size; the transplantation density is 0.5 m×0.5 m~1 m×1 m; the seagrass transplantation time includes autumn to winter.

9. The method according to any one of claims 1 to 7, characterized in that, The timing for sowing the bottom-buried shellfish is after the seagrass transplantation is completed; The specifications for the bottom-buried shellfish larvae are 110-130 individuals / kg; The sowing density of the bottom-buried shellfish larvae is 15-40 per m². 2 .

10. The method according to any one of claims 1 to 7, characterized in that, The mesh size of the enclosure net is smaller than that of the bottom-buried shellfish seedlings; the method of harvesting shellfish is to pick the larger ones and leave the smaller ones, while simultaneously replenishing the bottom-buried shellfish seedlings.

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