A method for constructing a mangrove planting and breeding coupling system in a pen

Abstract

The application belongs to the field of mangrove ecological restoration and resource utilization, and discloses a construction method of a mangrove planting and breeding coupling system in a pond. The application mainly comprises the following steps: performing topographic engineering reconstruction on the pond to be suitable for mangrove planting, determining the elevation of the mangrove planting in the pond according to the variation range of the breeding water level, replacing the natural tides with the change of the breeding water level to meet the needs of the mangrove plants in the pond for periodic immersion and dry exposure, optimizing the mangrove planting method in the pond, obtaining a breeding method of the mutual coupling of the mangrove plants and aquatic species, and realizing the consideration of both the mangrove planting and the aquatic breeding product output.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of mangrove ecological restoration and resource utilization, and particularly relates to the comprehensive technical field of mangrove planting and aquaculture. BACKGROUND

[0002] Mangrove is known as "coastal guard" and "ocean green lung", and has many important ecological functions such as wave protection, water purification, carbon fixation and storage, and biodiversity maintenance, which is of great significance to the safety of coastal ecosystem.

[0003] In the 1990s of last century, land-based mariculture was promoted in the coastal areas of southern China to increase the income of coastal people. Due to the rich tidal creek system and high aquatic resources in the mangrove area, many mangroves were cut down and reclaimed into aquaculture ponds. From 1980 to 2005, the global mangrove area decreased by nearly 20%, of which nearly half was due to the excavation of aquaculture ponds. Since 1980, 97.5% of the reduced mangrove area in China was caused by the excavation of aquaculture ponds.

[0004] The biggest difficulty in creating mangroves is to find suitable land. At present, most of the suitable land for mangroves has been planted with mangroves, and it is difficult to find more suitable land for afforestation. At present, the beach elevation available for mangrove restoration is low, and it is basically a deep water bare beach that cannot directly plant mangrove plants. Engineering ridge lifting or building wave protection dikes will not only increase the cost of afforestation, but also change the original topography of the marine beach, which will bring ecological risks. The aquaculture cofferdams and ponds in the coastal beach are suitable for mangrove growth, and using coastal aquaculture ponds to restore mangroves has become the most feasible method at present.

[0005] How to replant mangroves on the basis of maintaining the existing aquaculture ponds of fishermen has become a difficult point in the protection and restoration of mangroves. Under this background, based on the ecological concept of sand-based fish ponds in the Pearl River Delta, exploring the establishment of a mangrove planting-aquaculture ecological coupling mode in coastal aquaculture ponds is a win-win path to achieve both the completion of mangrove afforestation and the sustainable development of mariculture. However, the mangrove planting-aquaculture coupling mode is still in the stage of concept and experimental exploration, and many problems need to be further explored and solved.

[0006] At present, there are some technical bottlenecks in the promotion of mangrove reforestation and traditional aquaculture coupling technology in the same cofferdam or pond system, the reasons are as follows: 1. The requirements of mangrove plants and aquatic animals for water body or water level are not completely consistent. Mangrove plants need periodic immersion and dry exposure, while the local traditional aquaculture mode needs sufficient and stable water body environment to avoid external pathogenic bacteria and drastic changes of water quality indicators. 2. In the traditional cofferdam or pond system, aquaculture practitioners expect to obtain higher fish and shrimp yield, but the water quality of the cultivation system under such conditions is easy to deteriorate, and high-frequency use of lime, bleaching powder and other inputs is needed to control water quality, which will affect the survival of mangrove plants; water quality deterioration causes frequent fish and shrimp diseases, and high-frequency use of drugs, which is easy to cause water product quality and safety problems. 3. The demand of aquaculture practitioners for simplification of production links also leads to the difficulty of promotion and application of mangrove reforestation coupled with traditional aquaculture mode. The area of traditional aquaculture pond is relatively small, generally within 10 mu, the pond bottom is flat, there is no tidal ditch, the pond bank has no trees, and it is convenient for net harvesting and other production management. After coupling with mangrove reforestation, the water level needs to be periodically increased and decreased, which causes the complexity of cultivation management, and the surrounding mangrove also affects the normal use of netting tools, and the tidal ditch of the pond bottom will cause harvesting difficulty, which needs to change the production management mode. SUMMARY

[0007] The purpose of the present application is to provide a construction method of a mangrove planting and aquaculture coupling system in a (same) pond, mainly including a method of topographic engineering modification of the pond for suitable mangrove planting, an optimized method of mangrove planting in the cofferdam pond, an aquaculture method of mutual coupling of mangrove plants and aquatic species, and realization of mangrove planting and aquaculture product output.

[0008] The technical scheme adopted by the present application is:

[0009] A construction method of a mangrove planting and aquaculture coupling system in a pond, that is, a construction method of a mangrove planting and aquaculture coupling system in a same system in a mangrove area, comprising the following steps:

[0010] Select a coastal pond aquaculture area with natural distribution of mangrove plants, and the pond bank has the functions of realizing tidal water inflow and outflow and being closable.

[0011] If the water area and / or the area of the tidal ditch in the pond bank is not enough, artificial excavation can be performed to widen the area so that it meets the above-mentioned standard.

[0012] The pond bank is heightened and reinforced, and the top elevation of the pond bank is higher than the highest historical tide level of the surrounding sea by more than 1 m.

[0013] The soil required for reinforcing the embankment comes from the soil obtained when excavating the ponds within the embankment and the tidal channels. This maximizes the use of the soil excavated from the ponds within the embankment and the tidal channels, thus saving costs.

[0014] A pond within a pond is set up, with the area of ​​the pond being 8% to 12% of the total water area within the pond embankment. Fish farming cages are set up in the pond within the pond for raising fish.

[0015] This invention is the first to propose the concept of a pond within a pond, which is a coupled area of ​​mangrove planting and aquaculture within the same enclosed pond. The main purpose is to maintain the volume of aquaculture water, meet the depth requirements for cage fish farming, and improve the diversity of the aquaculture environment within the enclosed pond.

[0016] The pond within a pond is located in an area near a sluice gate, where strong water flow is conducive to water exchange and fish farming.

[0017] Preferably, the pond within a pond is set to occupy approximately one-tenth of the total water surface area. This is because the pond area contains net cages for intensive, high-density fish farming, resulting in a significant amount of uneaten feed, feces, and excrement. The pond within a pond, occupying approximately one-tenth of the total area, is used for intensive fish farming. This ensures both the fish production within the coupled system and the efficient utilization and transformation of uneaten feed and excrement at multiple trophic levels, guaranteeing the self-purification capacity and good water quality of the entire coupled system, thus maintaining its stability.

[0018] A tidal channel system is constructed within the enclosed pond, with interconnected channels forming a U-shape or figure-eight shape, and connected to the pond within the pond.

[0019] This invention increases the depth of the aquaculture water by setting up tidal channels, thus providing a suitable habitat and feeding ground.

[0020] The tidal channels are interconnected, forming a U-shape or figure-eight shape, and are linked to the ponds within the ponds, which facilitates the flow and exchange of water at the bottom, ensuring good water quality. The tidal channels run along the direction of the pond embankment and intersect with each other.

[0021] 5) Filling the pond side beach: The bottom mud obtained from excavating the pond-in-pond and tidal channels is used to fill the pond side beach. The structure of the pond side beach adopts a combination of steep slopes and gentle slopes. The slope ratio of the gentle slope is 1:30~1:20, and the lower edge of the gentle slope is 10~20 cm higher than the minimum water level for aquaculture control. It can be submerged and exposed with the rise and fall of the water level in the pond. The steep slope is located above the gentle slope, with a slope ratio of 1:1.5~1:1, and is not submerged. The gentle slope is planted with true mangroves, and the steep slope is planted with semi-mangroves.

[0022] This invention is the first of its kind to fill the pondside beach in the mangrove coupling area. The soil required for the pondside beach comes from the bottom mud produced by excavating the pond-within-a-pond and tidal ditch inside the enclosed pond. It is used for mangrove planting and restoration, and also plays a role in stabilizing the pond embankment to prevent collapse.

[0023] 6) setting double gate sluice: the double gate sluice controls the pond water inlet, drainage and breeding normal water level. The sluice includes a fixed sluice for controlling the breeding normal water level and a movable sluice connected with a power switch for controlling the breeding water level, the water level is controlled by the sluice, including the basic water level required by the breeding animals and the water body requirement required by the mangrove plants; the tolerance range of the dry or soaking time of the mangrove plants in the coupling system is found out through experiments. Every 10-15 days, water is filled during the high tide period in the outer sea, and water is drained during the low tide period. Among them, the drainage amount is 30-50 cm, which is carried out in 2-3 times; the water inlet amount is 30-50 cm, which is carried out in 2-3 times.

[0024] The sluice of the present application includes a fixed sluice (controlling the normal water level of breeding) and a movable gate (electric sluice) together.

[0025] The fixed sluice is set according to the normal water level required for breeding, and the height of the sluice is consistent with the normal water level. The electric sluice adopts a whole plate for convenient lifting; the fixed sluice (normal water level sluice) is composed of multiple gate plates, the width is 15-20 cm, and the length can be clamped in the gate plate edge groove.

[0026] The movable gate (electric sluice) is used to control the water level, if the electric sluice fails after lifting, the fixed sluice can be used to maintain the normal water level of breeding, to ensure the survival of the breeding organisms in the coupling system. Through the double insurance of the fixed sluice (controlling the normal water level) and the movable gate (electric sluice), the smooth progress of breeding production and mangrove protection is ensured.

[0027] Setting up aquaculture seedling marker small ponds, constructing marker small ponds in suitable corners of the pond, the area accounts for about 5%-10% of the total area of the total pond, which is used for marker breeding of prawn seedlings, and the marker small ponds are connected with the pond through small sluices and / or connecting pipes.

[0028] 8) planting mangrove plants, wherein the tree species planted in the gentle slope low tide area include Avicennia marina and / or Melia azedarach, the tree species planted in the middle tide area include Rhizophora stylosa, Kandelia candel, Avicennia marina and / or Melia azedarach, and the tree species planted in the high tide area include Bruguiera gymnorrhiza, Excoecaria agallocha and / or Lumnitzera littorea; the steep slope is planted with semi-mangrove broadleaf chrysanthemum and / or halogen fern.

[0029] The present application creates a mangrove planting method combining gentle slope area and steep slope area, which fully utilizes suitable areas and increases the planting area of mangroves and semi-mangroves.

[0030] The present application optimizes the mangrove planting combination method. Different mangrove tree species and semi-mangrove are planted in different elevation positions. The type of mangrove planted is determined according to the elevation range. Native tree species are preferentially used and the diversity principle is followed. The tree species planted in the low-tide area of the gentle slope include Avicennia marina and / or Bruguiera gymnorrhiza, etc. The tree species planted in the middle-tide area include Rhizophora stylosa, Kandelia candel, Avicennia marina and / or Bruguiera gymnorrhiza, etc. The tree species planted in the high-tide area include Bruguiera gymnorhiza, Ximenia americana and / or Lumnitzera littorea, etc. The semi-mangrove Aegiceras corniculatum and / or Enhalus acoroides, etc. are planted in the steep slope.

[0031] 9) coupling culture is carried out, the culture animals include yellow fin snapper, blue sub fish, prawn, green crab, oyster, siphon and the like or any combination thereof, the feeding habits of the above-mentioned culture animals are comprehensively considered to improve the utilization rate of nutrients;

[0032] Preferably, in step 3), the pond-in-pond is rectangular, the depth is 80-100 cm deeper than the original pond bottom, and the long axis direction of the pond-in-pond is consistent with the water flow direction.

[0033] The structure of the pond-in-pond is rectangular, the depth is 80-100 cm, and the long axis direction is consistent with the water flow direction of the surrounding pond, which is beneficial to water flow and water exchange. A water pump is used to regularly extract bottom pollutants. The main reason for setting the depth of 80-100 cm is to consider the water depth in the pond-in-pond when the normal water level in the coupling system is reached (the water level when the mangrove roots at the lowermost edge of the pond beach are just submerged), which is more than 2.2 m, ensuring the immersion depth of the net cage (net height 2.0 m) in the pond-in-pond.

[0034] Preferably, in step 5), when the pond beach is piled up, wooden stakes are vertically punched into the pond bottom at the outer edge of the gentle slope of the pond beach and boards are inserted to fix the earthwork of the pond beach.

[0035] Generally, the earthwork of the pond beach is first piled up, then the stakes and boards are punched and inserted when the earthwork is basically completed, and then the pond beach is leveled and piled up to form a complete pond beach.

[0036] More preferably, the pond bottom punching and board insertion includes the following steps: a wooden stake is punched in every 0.5-0.8 m, a wooden board is inserted into the inside of the wooden stake to form a baffle, and the wooden boards are overlapped with each other to increase the compression resistance.

[0037] More preferably, the wooden stake is 4-4.5 m long, 10-12 cm in diameter, and is inserted into the soil by 2-2.5 m. The wooden board is 2-3 m long, 0.20-0.30 m high, and 0.015-0.025 m thick, and a plurality of wooden boards are arranged in the long direction and vertically stacked.

[0038] Preferably, in step 5), a cofferdam is set up outside the mangrove planting area of the pond beach to ensure that the planting area is stable after the filling soil is raised in elevation, and to avoid water erosion of the soil in the planting area.

[0039] Preferably, in step 5), the bottom mud (earthwork) is piled up by combining pumping and excavating. The amount of earthwork required for the planting area of the beach is calculated according to the existing elevation of the various planting plots on the beach and the target elevation of the land preparation, and the required amount of earthwork is mainly obtained from the earthwork obtained by excavating the pond and the tidal ditch in the system.

[0040] Preferably, in step 5), the bottom mud of the pond in the pond is used as the surface layer of the beach, and the bottom mud of the pond in the pond and the bottom mud obtained by excavating the tidal ditch are used as the bottom layer of the beach.

[0041] Preferably, in step 6), the normal water level of the cultivation is between the lowest water level of the cultivation control and the highest water level of the cultivation control, and the highest water level of the cultivation control is slightly higher than the upper edge of the gentle slope by 5-10 cm. The normal water level is 8-12 cm lower than the lowest part of the mangrove distribution range, and the cultivation water level is varied within 0-50 cm based on the normal water level.

[0042] According to the variation range of the cultivation water level, the elevation of the mangrove planting in the enclosure is determined, and the change of the cultivation water level is used to replace the natural tides to meet the needs of the mangrove plants in the enclosure for periodic immersion and dry exposure.

[0043] Preferably, in step 6), the water level control of the control gate includes opening the water gate to fill water to immerse the mangrove plants on the beach during the spring tide, the water level reaches 5-10 cm above the base of the mangrove at the upper edge of the gentle slope of the beach, and the water is discharged after the mangrove is immersed for 5-10 days to expose the base of the mangrove at the lower edge of the gentle slope of the beach for 5-10 days, and the water level is controlled to rise and fall in this way.

[0044] Preferably, in step 8), before planting the mangrove, the elevation range of the true mangrove and semi-mangrove in the naturally distributed mangrove forest in the coupling area is measured by RTK (real-time dynamic measurement instrument), and the elevation range and the maximum elevation value of the planted mangrove plants are determined.

[0045] Preferably, in step 8), when planting the mangrove plants, the hole digging and planting are performed simultaneously, and the planting is performed as the hole is dug.

[0046] According to the artificially created enclosure cultivation coupling system, the water level variation rule of the system is determined, and the planting elevation range of different mangrove plants is set. Due to the erosion of seawater during the rise and fall of the tide, the hole digging and planting are performed simultaneously during the reforestation operation on the beach, and the planting is performed as the hole is dug. Artificial hole digging is adopted, and the hole size is slightly larger than the size of the planted seedling nutrient bag.

[0047] Preferably, in step 8), each mangrove plant is planted according to a 1.5 m x 1.5 m plant row distance, and a medium-sized seedling is preferably selected. Generally, the salinity of seawater in the project area is relatively high (18-25‰), and a mangrove seedling cultivated in a medium-high salinity environment is preferably planted.

[0048] For small seedlings and hypocotyls, due to the small size of the seedling bag, a single seedling bag cannot be firmly placed on the ground, so a block placement method is adopted, and multiple seedling bags are closely placed into a block with a length of 1 m and a width of 1.5 m (i.e. the width of the planting ridge), and the blocks are spaced 1 m apart.

[0049] For medium seedlings, a single seedling bag is independently placed on the ground, and the spacing between the seedling bags is 0.3 m.

[0050] For large seedlings, a single seedling bag is independently placed on the ground, and the spacing between the seedling bags is 0.4 m.

[0051] More preferably, in step 8), when planting mangrove plants, the container film bag is removed first and taken back to the shore for disposal as garbage. Hold the soil ball with your hand to prevent the root soil mass from loosening and the root system from being damaged. When the seedling is placed in the hole, it should be handled carefully, and the seedling should be held upright and lifted gently. After the soil is filled into the hole and covers the root system completely, the hand is released. This can reduce damage to the root system. Fill the soil to the surface of the soil ball, which should be flush with the ground surface.

[0052] Under normal circumstances, the area where semi-mangrove plants such as Acanthophacaria brachiata are planted (locations with an elevation of 2.3 m or above on the inner side of the dike) cannot be submerged in tidal water, and the soil is very dry. In addition, due to the overall higher elevation (1.9-2.3 m) of the planting area relative to the local average sea level (0.67 m), the mangrove planting area cannot be submerged in tidal water during neap tides (about twice a month, each time for 4-5 days). Therefore, within 1 month after the seedlings are planted, artificial watering is required for mangrove seedlings and semi-mangrove seedlings that are not submerged during neap tides. Watering is performed at intervals of 2 days during neap tides.

[0053] Preferably, in step 9), benthic organisms such as Onchidium struma and Acanthophacaria brachiata are raised in the gentle slope mangrove planting area; fish, shrimp, and crab are raised in the pond, oysters are hung, or shellfish are raised in the pond; fish is intensively cultured in the pond net cage; and residual feed and other accumulated materials in the pond are pumped to the mangrove planting area on a regular basis.

[0054] In the mangrove area, fast-growing and short-cultivation-cycle prawn farming is selected, and fish, shellfish, and special understory benthic organisms are co-cultured. This achieves the complementation of multiple ecological niches and improves material utilization. Prawns mainly feed on special feed, and the mixed fish feed on residual feed and sick prawns, reducing the spread of pathogenic bacteria; high-value fish is cultured in the pond, and high-quality feed is fed. The organic matter accumulated in the pond, such as residual feed and feces, is pumped to the beach near the mangrove planting area, and the organic matter promotes the growth of mangrove plants, thereby strengthening the carbon sequestration function of the mangrove plants.

[0055] Preferably, in step 9), after the aquaculture coupling is completed, the water level in the pond is lowered by opening the water gate to drain water, and small drag nets or ground cage nets are used to capture aquatic products such as fish, shrimp, and crab.

[0056] Preferably, in step 9), the prawns are cultivated by using phased cultivation, and first, prawn seedling cultivation is carried out in the thickening small pond in step 7), and then, when the prawns reach a length of 3-4 cm, the prawns are transferred to a (large) pond for cultivation, and part of the prawns are left to be cultivated in the small pond.

[0057] The water product seedling thickening small pond is arranged, a thickening small pond (hereinafter referred to as a small pond) is constructed in a suitable corner of the pond, and the area accounts for about 5-10% of the total area of the pond, and is used for prawn seedling thickening (3-4 cm) cultivation; the main reason is that the miscellaneous fish in the pond (hereinafter referred to as a large pond or a large pond) cannot be completely removed, so as to prevent the prawn seedlings (0.8-1.0 cm) just purchased from being eaten by the miscellaneous fish, and therefore, phased cultivation treatment is needed. In the large pond, the prawns and the fish need to be fed with special compound feed. The large pond and the small pond can be separated and connected through a pipeline or a gate, so as to facilitate the transfer of the prawns from the small pond to the large pond when the prawns reach a length of 3-4 cm.

[0058] Preferably, in step 9), the yellow snapper, blue fish and other fish are cultivated by first being fed in the pond net cage for feed domestication cultivation, and then being put into the large pond for cultivation after being adapted to the water environment and the feed, and part of the fry is left to be intensively cultivated in the net cage.

[0059] Preferably, special feed is fed in the prawn cultivation area and the fish net cage cultivation area. The filter-feeding shellfish can utilize the suspended particulate organic matter generated in the system, and the benthic animals such as mud worms can fully utilize the sediment-type particulate organic matter, so that the utilization rate of organic matter is fully improved.

[0060] Preferably, in step 9), according to the cofferdam area, oysters can be hung up and cage-cultured on the platform outside the tidal ditch.

[0061] The original cultivation pond in the application is reconstructed, including the heightening and reinforcement of the cofferdam pond dike (improving the wind and wave resistance), the beach filling on the pond side (increasing the number of mangrove planting), the construction of the pond in the pond (increasing the water product cultivation capacity and providing the required earthwork for the pond dike or the beach on the pond side), the reconstruction of the tidal ditch water system in the pond, the construction of the water inlet and outlet gate, etc. Through the above reconstruction, the output of mangrove planting and water product cultivation is realized.

[0062] The first important point of the application is that the coupling of mangrove re-planting and water product cultivation in the same cofferdam or pond system is realized.

[0063] The soil for mangrove planting is obtained from the pond in the pond in the same cultivation pond, so that the earthwork is self-sufficient, and the land is saved. The earthwork is obtained from the pond in the pond designed according to the structure and position of the pond.

[0064] The advantages of the pond-in-pond lie in: 1. The pond-in-pond increases the water depth and the breeding capacity of the pond, improves the ecological diversity of the breeding water body, especially the pond-in-pond and the tidal ditch increase the water depth and improve the complexity of the habitat, which is beneficial to the fish and shrimp to escape from the adverse environmental factors. 2. The pond-in-pond provides sufficient soil for the beach, which is used for the beach to accumulate and prevent waves, and the mangrove plants are planted on the beach. The 40-80 cm layer of the bottom mud of the pond is used as the surface layer of the beach, and the 0-40 cm layer of the mud of the pond is used as the base layer of the beach, which is used for digging holes and planting mangrove roots. 3. The soil of the pond-in-pond is rich in nutrients, which is generally silty clay, which is suitable for the root development and growth of mangrove plants.

[0065] The second invention point lies in: through the transformation of the pond and the control of the water gate, including the fixed water gate for controlling the normal water level of breeding and the electric water gate for frequently controlling the water inflow and outflow, the electric water gate is opened to soak the mangrove plants on the beach during the high tide, and after 5-10 days, the electric water gate is opened to discharge part of the water to expose the mangrove plants at the lowest edge of the beach, which guarantees the dry state and survival rate of the mangrove plants. The artificial tidal regulation in the pond meets the water level (water source) demand of the mangrove plants and guarantees the growth demand of the aquatic breeding animals. The artificial tidal system improves or increases the planting elevation range of the mangrove plants. For example, the water gate regulation of the pond increases the water level, which promotes the mangrove plants to grow to a higher elevation, and expands the planting and growth range of the mangrove plants. The innovative technical point lies in: according to the waterlogging and dryness tolerance of different mangrove plants, different mangrove plants are planted at different elevations and different water levels.

[0066] The third invention point lies in: the capture area during harvesting is transferred from the whole pond to the tidal ditch and the pond-in-pond. The water level of the pond is lowered, and the fish and shrimp enter the tidal ditch and the pond-in-pond, and small drag nets or ground cage nets are used to capture the fish and shrimp. At the same time, oysters are hung and gill net cultured on the land outside the tidal ditch.

[0067] The fourth invention point lies in: breaking the traditional intensive breeding mode, developing a comprehensive ecological breeding mode, and introducing main breeding species and matching species. In the mangrove forest area, fast-growing and short-cycle prawns are selected for breeding, and fish, shellfish and special under-forest benthic organisms are matched for breeding. The complementary of multiple ecological niches is realized, and the material utilization rate is improved. Prawns mainly feed on special feed, and mixed fish feed on residual feed and sick prawns to reduce pathogen transmission; high-value fish are bred in the pond-in-pond, and high-quality feed is fed. The organic matter such as residual feed and feces accumulated in the pond-in-pond is pumped to the beach where the mangrove plants are planted, and the organic matter promotes the growth of the mangrove plants, thereby strengthening the carbon sink function of the mangrove plants.

[0068] The beneficial effects of the present application are:

[0069] 1) The present application realizes the coupling of mangrove and aquatic species by the topographic engineering reconstruction of the enclosure for suitable mangrove planting, and the optimization of the mangrove planting method in the enclosure.

[0070] 2) The present application uses an ecological complementary multi-functional breeding area. The prawn main breeding area, the fish pond net cage breeding area, the filter-feeding shellfish breeding area, and the benthic animal breeding area are arranged in the coupling system. The breeding water and space are fully utilized to realize the maximum utilization rate of organic matter, and the accumulation of organic matter at the bottom of the breeding water can be reduced.

[0071] 3) Only in the prawn breeding area and the fish net cage breeding area, special feed is fed, while the filter-feeding shellfish can use the suspended particulate organic matter produced in the system, and the benthic animals such as mud worms can fully utilize the sedimentary particulate organic matter, thereby improving the utilization rate of organic matter.

[0072] 4) The organic matter in the pond pond sewage collection area is further pumped into the mangrove planting area, and the nutrients can be utilized by the mangrove plants, thereby realizing the effective utilization of organic matter, purifying the bottom environment of the enclosure, improving the growth environment of fish, shrimp and crab, and promoting the growth effect of mangrove plants.

[0073] 5) The bottom sediment of the enclosure is improved. BRIEF DESCRIPTION OF DRAWINGS

[0074] Figure 1 It is a fixing method of wooden piles and boards.

[0075] Figure 2 It is an example of the beach beside the pond.

[0076] Figure 3 It is the mangrove plants and water level situation of the beach beside the pond.

[0077] Figure 4 It is the cultivation of mangrove seedlings in the nursery pond.

[0078] Figure 5 It is the field map of the excavation of the pond pond.

[0079] Figure 6 It is the field map of the excavation of the tidal ditch. DETAILED DESCRIPTION

[0080] The present application will be described in detail in conjunction with specific embodiments, but the scope of the present application is not limited.

[0081] The materials used in this embodiment, etc., are materials obtained from commercial channels, unless otherwise specified. EMBODIMENT

[0082] Location: the enclosure pond in the mangrove area of Leigao Town, Leizhou City; Time: April 2023 to May 2024.

[0083] This embodiment is set in Leigao Town, and a small enclosure pond is built in the corner of the enclosure pond (hereinafter referred to as the large pond). The small enclosure pond is separated from the enclosure pond by a dam, and is connected to the enclosure pond by a connecting pipe.

[0084] The small pond is a pond that is matched with the prawn culture and mangrove reforestation in the large pond. The area is relatively small, about 5-10 mu, and is used to culture prawns to 3-4 cm. The main reason is that the miscellaneous fish in the large pond cannot be completely removed, so as to prevent the newly purchased prawn larvae (0.8-1.0 cm) from being eaten by miscellaneous fish. Therefore, the prawn larvae are temporarily raised in the small pond. There is no pond-in-pond in the small pond.

[0085] The large pond is a mangrove species cultivation coupled enclosure pond where the pond edge beach, pond-in-pond, and tidal ditch are located. In the large pond, prawns and fish need to be fed with special matching feed. The pond-in-pond area in the large pond is for placing net cage culture platforms and net cage culture, which can culture commercial size fish.

[0086] A construction method for realizing a mangrove area coupled with a mangrove planting and aquaculture system in the same system, comprising the following steps:

[0087] 1. Site selection criteria for planting-culturing coupled area: Select an area with mangrove plant resources. The area can realize tidal water intake and discharge, and has a closable pond dam foundation.

[0088] 2. Modification method of enclosure pond: The modification of the enclosure pond includes the heightening and reinforcement of the cofferdam pond dam (to improve the wind and wave resistance), the heap filling method of the pond edge beach (to increase the number of mangrove planting), the construction method of the pond-in-pond (to increase the water capacity for aquaculture), the modification method of the tidal ditch system in the enclosure pond, and the construction method of the water intake and discharge gate. The specific methods are as follows:

[0089] 1) Reinforcement method of cofferdam pond dam:

[0090] Determine the elevation of the planting-culturing area pond dam according to the historical highest tide level. The elevation of the top of the cofferdam pond dam is higher than the historical highest tide level outside the enclosure pond by more than 1 m.

[0091] The soil needed for the reinforcement of the cofferdam pond dam comes from the pond-in-pond and the tidal ditch inside the cofferdam, which can save soil and cost to the maximum extent.

[0092] The specific operation is as follows:

[0093] The average tidal level of the outside of the mangrove planting and breeding coupling area is 0.67 m (1985 elevation system, hereinafter the same), and the highest tidal level is 2.76 m. The highest elevation of the pond dike of the mangrove area is 3.91 m, which can meet the production demand of breeding. In order to improve the superposition effect of the pond dike against storm surge, the pond dike is widened and reinforced to 4.41 m in the example. The above values are elevation values.

[0094] 2) Pile-up method of beach on the edge of pond

[0095] The application initiates the pile-up method of beach on the edge of pond in the coupling area of mangrove, and the soil required by the beach on the edge of pond comes from the bottom mud of the pond-in-pond inside the cofferdam and the tidal ditch, which is used for mangrove planting and repair and pond dike reinforcement against wind and wave, and belongs to a measure that achieves multiple purposes at a time.

[0096] Specifically, the structure of the beach on the edge of pond adopts the combination of steep slope and gentle slope. The gentle slope is used for planting true mangrove, and the steep slope is used for planting semi-mangrove. The gentle slope is close to the breeding water body and can be regularly soaked and exposed by the breeding water body, the slope ratio of the gentle slope is 1:30~1:20, and the lower edge of the gentle slope is 10~20 cm higher than the lowest water level of breeding control, so that the gentle slope can be soaked and exposed with the rise and fall of the water level in the pond; the steep slope is located above the gentle slope, the slope ratio is 1:1.5~1:1, and the steep slope is not soaked.

[0097] After the positions of the gentle slope and the steep slope are determined, piles and boards are vertically punched on the inside of the gentle slope to fix the earthwork of the beach on the edge of pond. The pile and board fixing method is that a cedar pile is punched every 0.5~0.8 m, a pine board is inserted on the inside of the cedar pile to form a baffle, the pine boards are overlapped with each other to increase the compression resistance. The wood pile is 4 m long, 10 cm in diameter, and 2 m in insertion depth. The pine board is 2 m long, 0.85 m high, and 0.015 m thick, and the boards are arranged in the length direction. See Figure 1 .

[0098] The cofferdam is arranged outside the mangrove planting area of the beach on the edge of pond to ensure that the soil filling of the planting area is lifted to a stable state after the filling, so as to avoid the erosion of the soil in the planting area by water flow.

[0099] The earthwork is filled by combining pumping and digging and transporting. The required earthwork amount of the planting area of the beach on the edge of pond is calculated according to the existing elevation of the planting plot and the target elevation of land preparation. The required earthwork amount is obtained from the earthwork amount obtained from the pond-in-pond and the tidal ditch inside the system and the earthwork amount transported outside.

[0100] 3) Determining the elevation range of mangrove planting in the coupling area

[0101] The elevation range of the natural resources (true mangrove and semi-mangrove) of mangrove plants in the coupling area is measured by RTK to obtain the minimum elevation and maximum elevation values.

[0102] The normal water level (normal water level) required by the cultivated organisms in the pond is determined according to the elevation of the highest part of the pond bottom. The normal water level is about 8-12 cm lower than the lowest part of the mangrove distribution range. On the basis of the normal water level for cultivation, the fluctuation range of the cultivation water level is 0-50 cm.

[0103] After piling outside the mangrove planting area on the pond beach, the filling is lifted to the minimum and maximum limits of the fluctuation range of the cultivation water level.

[0104] The present application determines the mangrove planting elevation in the pond according to the fluctuation range of the cultivation water level, and the change of the cultivation water level instead of natural tides to meet the water demand of the mangrove plants in the pond. (Natural tides-pond water level)

[0105] Pond (large pond): Since the normal water level for project cultivation is set to 1.80 m, the fluctuation range of the cultivation water level is 1.80 m to 2.30 m. The elevation of the mangrove planting area on the pond beach is set to 10 cm above the normal water level to the maximum cultivation water level, i.e. the elevation interval of the mangrove planting area on the pond beach is set to 1.90 m-2.30 m. The schematic diagram of the pond beach is shown in Figure 2 , and the real scene is shown in Figure 3 . Figure 3 For the mangrove plants and water level of the pond beach, the right side of the pond dike is the natural mangrove on the sea.

[0106] Large pond (small pond): According to the local average sea level and high tide level, the elevation of the mangrove planting area on the pond beach in this project is located in the high tide zone. The existing elevation of the small pond (nursery) is 1.51 m on average, which is located in the suitable elevation range for mangrove growth. The real scene is shown in Figure 4 .

[0107] 4) Pond-in-pond transformation method

[0108] The present application first proposes the concept of pond-in-pond in the mangrove planting-cultivation coupling area, the main purpose of which is to increase the area of mangrove planting in the pond without reducing the volume of cultivation water body, and to ensure the cultivation capacity of the coupling system. The main difference between the pond-in-pond and the ring ditch in the prior art is that the pond-in-pond can be used for net cage facility cultivation, installation of floating platform, hanging net and oxygenation facilities, and realization of high-density cultivation. The ring ditch in the prior art is used as an environment for fish and shrimp cultivation, which is suitable for ecological cultivation type and cannot be used for facility cultivation, and the yield is relatively low.

[0109] Site selection of pond-in-pond. In the area close to the water gate, the water flow is strong, which is convenient for water exchange and beneficial to fish cultivation.

[0110] Setting the size of the pond-in-pond: about one-tenth of the total water area. Because the pond-in-pond area is provided with net cages, mainly for fish farming, the farming density is relatively large, and there is more accumulation of residual feed and feces. The high-density fish farming in the pond-in-pond can not only ensure the fish output in the coupling system, but also ensure the coupling system's mitigation of the particulate organic matter and chemical oxygen demand generated by fish farming, ensuring the self-purification ability and good water quality of the entire coupling system, which can maintain the stability of the coupling aquaculture system.

[0111] Setting the structure of the pond-in-pond: rectangular, with a depth of 80-100 cm deeper than the original pond bottom, and the long axis direction consistent with the water flow direction of the surrounding pond, which is conducive to water flow and water exchange. The depth gradually increases from the inside of the surrounding pond to the water gate direction, forming a height difference, which is conducive to water discharge and particulate matter discharge. The main reason for setting a depth of 80-100 cm is to consider that when the normal water level in the coupling system (the water level when the mangrove roots at the lowermost edge of the pond bank are just submerged) is 2.2 m or more, the water depth in the pond-in-pond is ensured. The depth of the excavated pond-in-pond site is shown in Figure 5 , and the tidal ditch site is shown in Figure 6 .

[0112] 5) Modification method of tidal ditch water system in the surrounding pond

[0113] By setting the tidal ditch, the depth of the aquaculture water body is increased, and suitable habitat feeding sites are provided.

[0114] The tidal ditches are connected, in the shape of a back-to-back or an 8, and are connected to the pond-in-pond, which is conducive to the flow and exchange of the bottom water body, ensuring good water quality at the bottom. The tidal ditch runs along the direction of the pond embankment and is connected in cross.

[0115] Tidal ditch structure: width 8 m, depth 60-80 cm, and connected to the pond-in-pond.

[0116] 6) Modification method of water gate

[0117] The water gate of the present application includes a fixed water gate (controls the normal water level of cultivation) and a movable gate plate.

[0118] The fixed water gate is set according to the normal water level required for cultivation, and the height of the water gate is consistent with the normal water level of cultivation. The water gate can be a whole plate or multiple wooden plates; the movable water gate is composed of multiple gate plates, with a width of 15-20 cm, and its length can be clamped in the slot at the edge of the gate plate.

[0119] Every 10-15 days during the rising tide period, drainage and water intake are carried out. Among them, the drainage water level is lowered by 30-50 cm, and the water intake water level is increased by 30-50 cm. The total nitrogen content of the drainage is less than 6.0 mg / L, and the total phosphorus content is less than 1.5 mg / L, which meets the Guangdong Province aquaculture tail water discharge standard.

[0120] Reformation of small enclosure

[0121] Select 5 mu area on one side of the enclosure as the site for the prawn seedling reformation, i.e. small pond. First, separate the small pond from the large pond with a dike. The dike around the small pond needs to be reinforced and compacted to prevent dike collapse. The mud used for the dike comes from the tidal ditch. A 8 m wide tidal ditch is dug around the small pond, with a depth of about 1.2 m, and the bottom is compacted without pits. The slope ratio on both sides of the tidal ditch is maintained at a certain value (less than 1 / 2), which is beneficial for the migration and feeding of prawn larvae. The small pond can also be used for mangrove seedling cultivation, and the remaining terrace in the middle of the small pond can be used to plant mangrove seedlings.

[0122] 1) The present invention creates a mangrove planting method that combines gentle slope areas and steep slope areas, making full use of suitable areas and increasing the planting area of mangroves and semi-mangroves.

[0123] 2) The present invention optimizes the mangrove planting combination method. Different mangrove species and semi-mangroves are planted at different elevations. The type of mangrove planted is determined according to the elevation range. According to the principles of suitable location for suitable trees, preferential use of native tree species, and diversity, the tree species planted in the low tide zone of the gentle slope include Avicennia marina and / or Kandelia candel, the tree species planted in the middle tide zone include Rhizophora stylosa, Kandelia candel, and / or Avicennia marina, and the tree species planted in the high tide zone include Bruguiera gymnorrhiza, Excoecaria agallocha, and / or Cerbera manghas; the semi-mangrove planted on the steep slope includes Aegiceras corniculatum and / or Enhalus acoroides.

[0124] Example (large pond): The elevation of the mangrove planting area in the implementation area is 1.8-2.3 m, belonging to the high tide zone. In order to meet the water demand of the breeding organisms during the ebb tide period, the constant water level is maintained at 1.8 m, and most of the root systems of mangrove plants are concentrated in the surface layer of 10-20 cm, therefore, the mangrove plants near the constant water level can absorb water from the breeding pond. Specifically, Avicennia marina or Kandelia candel is planted in the land block with an elevation of 1.8-1.9 m, Rhizophora stylosa or Kandelia candel or Avicennia marina is planted in the land block with an elevation of 1.9-2.1 m, Cerbera manghas is planted in the land block with an elevation of 2.1-2.3 m, and Aegiceras corniculatum or other semi-mangrove species is planted at an elevation of more than 2.3 m.

[0125] 3) Mangrove planting density and quantity

[0126] The planting area of the pond beach is planted with each mangrove plant according to a 1.5 m x 1.5 m plant row spacing, and medium-sized seedlings are selected. Due to the high salinity of seawater in the project area (18-25‰), it is appropriate to plant mangrove seedlings cultivated in a medium-high salinity environment.

[0127] For small seedlings and embryos, due to the small size of the seedling bags, a block placement method is adopted, and multiple seedling bags are closely placed into a block with a length of 1 m and a width of 1.5 m (i.e. the width of the planting ridge), and the blocks are spaced 1 m apart.

[0128] For medium seedlings, individual seedling bags are placed independently on the ground, with a spacing of 0.3 m between the seedling bags.

[0129] For large seedlings, individual seedling bags are placed independently on the ground, with a spacing of 0.4 m between the seedling bags.

[0130] 4) Mangrove planting method

[0131] According to the artificially created pond breeding coupling system, the water level variation law of the system is determined, and the planting elevation range of different mangrove plants is set.

[0132] Due to the scouring of seawater during the rising and falling tides, the hole digging and planting are carried out simultaneously during the afforestation operation on the mudflat. Artificial hole digging is adopted, and the hole specification is slightly larger than the nutrient bag of the planted seedlings.

[0133] When planting, the container film bag is removed first and taken back to the shore for disposal as garbage. The soil ball is held with the hand to prevent the root soil mass from loosening and the seedling root system from being damaged. The seedling should be lifted and placed gently when entering the hole. The hand is used to support and lift lightly. After the soil completely covers the root system, the hand is released. This can reduce the damage to the root system. The soil is filled to the surface of the soil ball, which is flush with the ground surface.

[0134] The Aegiceras corniculatum planting area (the location with an elevation of 2.3 m or above on the inner side of the pond dam) cannot be submerged in the tidal water, and the soil is very dry. In addition, due to the overall higher elevation (1.9-2.3 m) of the planting area relative to the local average sea level elevation (0.67 m), the mangrove planting area cannot be submerged in the tidal water during the neap tide period (about twice a month, each time for 4-5 days). Therefore, within 1 month after the seedling planting, artificial watering is required for the mangrove seedlings and semi-mangrove seedlings that are not submerged during the neap tide period. Watering is carried out at an interval of 2 days during the neap tide period.

[0135] Mangrove planting method in nursery

[0136] A planting ridge is piled up in the nursery, with a width of 1.5 m. An inter-ridge ditch with a width of 0.5 m is provided between adjacent planting ridges as a pedestrian passageway for nursery operation. One planting ridge is provided for each of the large seedlings, medium seedlings, small seedlings, and embryonic axes (the embryonic axes are only applicable to the Kandelia candel and Rhizophora stylosa) of the six tree species of Avicennia marina, Rhizophora stylosa, Kandelia candel, Bruguiera gymnorrhiza, Excoecaria agallocha, and Ximenia americana. For small seedlings and embryonic axes, due to the small size of the seedling bags, individual seedling bags cannot be stably placed on the ground. Therefore, a block placement method is adopted, in which multiple seedling bags are closely placed into blocks with a length of 1 m and a width of 1.5 m (i.e., the width of the planting ridge). The blocks are spaced 1 m apart. For medium seedlings, individual seedling bags are placed independently on the ground, with a spacing of 0.3 m between the seedling bags. For large seedlings, individual seedling bags are placed independently on the ground, with a spacing of 0.4 m between the seedling bags.

[0137] 4. Method for releasing and managing breeding species

[0138] 1) Before releasing the shrimp fry, the water in the small pond is lowered below the surface of the platform, then bleaching powder is dissolved and sprayed for disinfection, and aeration is carried out for two days. Then 1.3-1.5 million juvenile prawns (body length: 0.8 cm) are released into the small surrounding pond (small pond) of the nursery, and after 25-30 days of cultivation (body length 3-4 cm), the net is pushed to capture and transfer to the large pond.

[0139] 2) The prawns and mud crabs can be mixed with yellow snapper or blue fish, etc. The prawn culture density is 20-30 thousand tails / m2 of water surface, and the fry release size is 1.0-1.2 cm / tail. The release time is adjusted flexibly according to local water temperature, salinity, rainfall, etc.

[0140] Mud crabs are released when prawns are cultured for about 40 days, with a density of 150-200 per mu and a size of 20-30 grams per crab.

[0141] The release density of yellow snapper or blue fish is 500-800 tails, with a size of 5-7 cm, and the fry release time is in May every year, about 30 days after the release of prawn fry.

[0142] Release the mudworm (Grenula) in the light beach or the ridge area where the water grass grows in the coupled system, with a release density of 100-200 strips / m 2 , and a size of 1-3 g / strips.

[0143] Insert the oyster poles on the platform to use the suspended particulate matter in the cofferdam to improve water quality and stability. The hanging ratio is determined according to the primary productivity and the amount of fish and shrimp bait generated in the cofferdam, which accounts for about one twelfth of the area of the pond.

[0144] The growth effect of mangrove plants is shown in Table 1.

[0145] Table 1 Comparison of mangrove plants in restoration area and natural area

[0146]

[0147] As shown in Table 1, in the mangrove breeding coupling system, 5 kinds of mangroves (Kandelia candel, Avicennia marina, Aegiceras corniculatum, Rhizophora stylosa, Rhizophora stylosa) and 1 kind of semi-mangrove plants can be planted in the beach of the pond, which is more than the number of mangrove plants per unit area (natural area), especially more than the number of mangrove species in the beach with Sonneratia alba as the dominant species. Because Sonneratia alba is an alien species, it has obvious growth advantage, fast growth, large canopy, and easy to cause shading effect, which affects the growth of other mangrove plants.

[0148] Since the present application is provided with the slope area and steep slope area, the mangrove in different area can receive light well without shade, and the survival rate is higher, and the growth effect is better than that of the native mangrove plant in natural state. In contrast, the current natural mangrove area is dominated by the alien species-Spartina alterniflora, and most of the other native mangrove species are obviously affected by the shade. In the long run, the distribution of mangrove species in the natural mangrove is not conducive to the long-term healthy development of the mangrove.

[0149] The cultivated animals grow: in the mangrove breeding coupling system, ecological breeding and intensive breeding coexist, and the net cage in the pond is used for the fingerling culture and the intensive growth of part of fish, the pond water is mixed with yellow snapper, blue fish, mud crab and prawn, and the breeding density is relatively low. The results are shown in Table 2.

[0150] Table 2 Comparison of breeding benefits of different modes

[0151]

[0152] As shown in Table 2, the prawn breeding density is 20,000 tails per mu, the survival rate is 75%, the yield is 300 kg per mu, the unit price is 20 yuan per kg, and the sales amount is 300,000 yuan. The yellow snapper is 250 tails per mu, the survival rate is 90%, the annual yield is 3375 kg, and the sales amount is 10.125 million yuan; the blue fish is 2000 tails per mu, the survival rate is 95%, the annual yield is 28500 kg, and the sales amount is 79.8 million yuan; the breeding product sales amount of the Aplysia juliana is 2.016 million yuan; and the breeding product sales amount of the mud crab is 5.0 million yuan.

[0153] In summary, the total benefit of the mangrove breeding coupling mode is 126.94 million yuan. In the control pond, the breeding species are prawn and tilapia, the prawn yield is 350 kg per mu, the tilapia yield is 3000 kg per mu, and the total sales amount of the control breeding mode is 110 million yuan. The sales amount of the mangrove breeding coupling ecological breeding is slightly higher than that of the control breeding mode.

[0154] Because the control is the traditional mode near the mangrove-breeding coupling, there is no re-planting of mangrove, and there is no diversity of mangrove, and there is no other effect of the diversity of mangrove on the local area. In summary, the construction method of the mangrove planting and breeding coupling system of the present application can realize the re-planting of mangrove, improve the diversity of mangrove, and increase the income of farmers without affecting the income of farmers. The method is more easily accepted by local farmers, and has great significance.

[0155] In addition to economic benefits, the mangrove breeding coupling system in the enclosure pond also achieves more ecological benefits. For example, compared with traditional breeding ponds, the biological diversity of the mangrove breeding coupling system of the present application is significantly increased, especially the number of Peristedion orientale. During the breeding period, the water quality of the pond is good. Every 10-15 days during the flood tide period, the water is drained and the water is filled. Among them, the water level is lowered by 30-50 cm, and the water level is increased by 30-50 cm. The total nitrogen content of the drained water is less than 6.0 mg / L, and the total phosphorus content is less than 1.5 mg / L, which meets the Guangdong Province Aquaculture Effluent Discharge Standard.

[0156] Comparative Example 1

[0157] A mangrove coupled with Chinese snakehead breeding pond (utility model CN202120564297.X) sets up a breeding area, a planting area and a seabird feeding area structure in an open intertidal zone, and the area ratio is about 1:1:1. The patent is aimed at planting mangroves and low-oxygen tolerant breeding species in an open intertidal zone, and does not involve the method of coupling mangrove planting and aquaculture in the same enclosure system.

[0158] Comparative Example 2

[0159] The mangrove area transplanted coupling big Peristedion orientale breeding method (CN201811327681.7) mainly uses mangrove to purify the water quality of breeding tail water and improve the breeding scale of big Peristedion orientale. It does not involve the development of related technologies and methods for coupling mangrove and aquatic species in the enclosure system. The patent technology does not involve the transformation of pond-in-pond and pond beach and the elevation setting.

[0160] The present application relates to the engineering modification of the enclosure pond, which fully considers the slope design of the pond beach, which is suitable for both mangrove plants and water level requirements of aquatic animals.

[0161] The above is a further detailed description of the present application, which cannot be considered as a limitation of the specific implementation of the present application. For ordinary skilled persons in the technical field to which the present application belongs, simple deduction or replacement without departing from the concept of the present application is within the protection scope of the present application.

Claims

1. A method for constructing a mangrove plantation and aquaculture coupled system in a pen, characterized in that, Includes the following steps: 1) Select a coastal enclosed aquaculture area with natural distribution of mangrove plants, where the enclosed pond dikes are designed to allow for tidal water inflow and outflow and can be closed off; 2) Raise and reinforce the dike, with the top of the dike being at least 1 meter higher than the historical highest tide level in the outer sea of ​​the dike. 3) Set up a pond within a pond, with the area of ​​the pond within a pond being 8% to 12% of the total water area inside the pond embankment. Aquaculture cages are set up in the pond within a pond for raising fish. 4) Construct a tidal channel system within the enclosed pond, with the channels interconnected in a U-shape or figure-eight shape, and connected to the pond within the pond; 5) Filling the pond banks: The bottom mud obtained from dredging the ponds and tidal channels is used to fill the pond banks. The structure of the pond banks adopts a combination of steep and gentle slopes. The slope ratio of the gentle slope is 1:30 to 1:20, and the lower edge of the gentle slope is 10 to 20 cm higher than the minimum water level for aquaculture control. It can be submerged and exposed as the water level in the pond rises and falls. The steep slope is located above the gentle slope, with a slope ratio of 1:1.5 to 1:1, and is not submerged. The gentle slope is planted with true mangroves, and the steep slope is planted with semi-mangroves. 6) A double-gate sluice gate is installed to control the water intake, drainage, and normal water level of the enclosed pond for aquaculture. The double-gate sluice gate includes a fixed sluice gate for controlling the normal water level of aquaculture and an electric sluice gate connected to a power switch for controlling the water level of aquaculture. The water level is regulated by controlling the sluice gate, including the basic water level required for aquaculture animals and the water level required for mangrove plants. The tolerance range of mangrove plants to dry exposure or soaking time in the coupled system is determined through experiments. Water is introduced during high tide in the open sea every 10 to 15 days, and water is discharged during low tide. 7) Set up small enclosures for raising aquatic seedlings. Construct small enclosures for raising aquatic seedlings in suitable corners of the main enclosure, with an area accounting for 5% to 10% of the total area of ​​the main enclosure. These small enclosures are used for raising shrimp seedlings. The small enclosures are connected to the main enclosure through small sluice gates and / or connecting pipes. 8) Plant mangrove plants, including Avicennia marina and / or Avicennia marina in the low tide zone on gentle slopes, Avicennia marina and / or Avicennia marina in the mid tide zone, and Avicennia marina and / or Avicennia marina in the high tide zone; and Rhizophora stylosa, Excoecaria agallocha and / or Prunus armeniaca in the high tide zone; and semi-mangrove chrysanthemum and / or Pteridium brevicornu on steep slopes. 9) Conduct aquaculture, with farmed animals including yellowfin seabream, bluefish, shrimp, mud crab, oyster, and Sipunculus nudus.

2. The construction method of claim 1, wherein, Step 3) The inner pond is rectangular, and its depth is increased by 80-100 cm from the original pond bottom. The long axis of the inner pond is aligned with the direction of water flow.

3. The construction method of claim 1, wherein, In step 5), when filling the pond bank, drive wooden stakes perpendicular to the bottom of the pond and insert boards to fix the soil on the pond bank at the outer edge of the gentle slope of the pond bank.

4. The construction method of claim 1, wherein, In step 6), the normal water level for aquaculture is between the minimum and maximum water levels for aquaculture control, with the maximum water level for aquaculture control being 5-10 cm higher than the uppermost edge of the gentle slope.

5. The construction method of claim 1, wherein, In step 6), controlling the water level by opening the sluice gate during high tide involves flooding the mangrove plants on the pond bank with water. The water level should reach 5-10 cm above the base of the mangroves at the uppermost edge of the gentle slope of the pond bank. After flooding the mangroves for 5-10 days, the sluice gate should be opened again to drain some water, exposing the base of the mangroves at the lowest edge of the gentle slope of the pond bank for 5-10 days. This cycle is repeated to control the rise and fall of the water level.

6. The method of construction of claim 1, wherein: In step 8, before planting mangroves, the elevation range of true mangroves and semi-mangroves in the naturally distributed mangrove forest is measured by RTK to determine the elevation range and the maximum elevation value of the mangrove plants to be planted.

7. The construction method of claim 1, wherein, In step 9, benthic organisms are raised in the gentle slope mangrove planting area; fish, shrimp, and crab are raised in the enclosure, oysters are hung, and shellfish are raised on the bottom; fish is intensively cultured in the pond net cage; and waste accumulated in the pond is pumped to the mangrove planting area at regular intervals.

8. The construction method of claim 1, wherein, In step 9, the shrimp is raised using a phased culture method, first in the small enclosure in step 7 for large-scale shrimp seed culture, and then transferred to the large enclosure for culture when the shrimp body length reaches 3-4 cm, with some shrimp continuing to be cultured in the small enclosure.

9. The construction method of claim 1, wherein, In step 9, the yellow snapper and blue fish are first cultured in the pond net cage for feed acclimation, and then transferred to the large enclosure for culture after adapting to the water environment and feed, with some fish fry continuing to be intensively cultured in the net cage.

10. The construction method of claim 1, wherein, In step 9, during the later stage of aquatic coupling culture, when the cultured aquatic products are harvested, the water level in the enclosure is lowered by opening the water gate, and small drag nets or ground cage nets are used to capture fish, shrimp, and crab.

Images