Three-dimensional estuarine fishery habitat restoration device and investigation and assessment method
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- EAST CHINA SEA FISHERIES RES INST CHINESE ACAD OF FISHERY SCI
- Filing Date
- 2025-01-09
- Publication Date
- 2026-07-02
Smart Images
Figure CN2025071527_02072026_PF_FP_ABST
Abstract
Description
Three-dimensional device and survey and assessment method for estuarine fishery habitat restoration Technical Field
[0001] This invention relates to the field of fishery ecological restoration technology, specifically to a three-dimensional device for estuarine fishery habitat restoration and a survey and assessment method. Background Technology
[0002] Estuarine fishery habitats are an important part of the ecosystem. They not only provide habitats for numerous aquatic organisms, but also play a key role in maintaining ecological balance and human fishing activities. However, with the continuous increase in human activities, the ecological environment of estuaries has been severely damaged, fishery habitats have gradually degraded, leading to a decline in biodiversity and a reduction in fishery resources. In order to address this problem, fishery ecological restoration technology has emerged, aiming to restore and improve estuarine fishery habitats through scientific methods.
[0003] While traditional three-dimensional restoration devices can improve fishery habitats to some extent, they still have some obvious drawbacks. They lack a comprehensive consideration of the habitat needs of different aquatic organisms. Although gabion cages can provide habitats for shrimp, crabs and benthic organisms, they lack flexibility and adaptability. Especially in silt-prone estuaries, the cages are easily silted up and lose their function of providing habitats, making it difficult to meet the needs of dynamic changes in biological communities.
[0004] In summary, traditional fishery ecological restoration technologies have certain limitations in the restoration of estuarine fishery habitats. To overcome these shortcomings, the present invention proposes a three-dimensional device for estuarine fishery habitat restoration and a survey and evaluation method, which is of particular importance. Summary of the Invention
[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a three-dimensional device and survey and evaluation method for the restoration of estuarine fishery habitats. It can provide diverse habitats for different species of aquatic organisms by constructing a three-dimensional restoration device that includes a floating plant bed area, a pipe reef area, and a gabion cage area. Through systematic survey and evaluation methods, the restoration effect can be accurately evaluated to achieve the comprehensive restoration and improvement of estuarine fishery habitats.
[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a three-dimensional device for the restoration of estuarine fishery habitats, which includes a floating plant bed area, a pipe reef area, a gabion cage area and a stainless steel frame structure (5):
[0007] The plant floating bed area (1) includes: foam float (701), angle iron (702), screw holes (703) on the angle iron for fixing the floating bed, plant roots (704), and polyethylene mesh (705).
[0008] The pipeline reef area (2) includes: a stainless steel frame (201), a PVC pipe (202), a first nylon rope (203), and a hole (204) in the PVC pipe;
[0009] The gabion area (3) includes: a stainless steel frame (301), a wire mesh cage (302), and stones (303);
[0010] Floating Plant Area: Located on top of the stainless steel frame structure, this area consists of foam floats, a stainless steel tubular frame, and floating plant modules. The upper part of the stainless steel frame is welded into nine squares using angle irons. Each square holds a floating plant module, which is then secured to the frame with screws through holes in the angle irons. Each floating plant module comprises two layers of polyethylene mesh and a central layer of plant roots, secured with plastic cable ties. The entire floating bed frame is nested within the stainless steel frame, located at the top, and connected to the frame by nylon ropes. The surrounding foam floats allow the floating bed to float with the tides without detaching from the frame. Plant growth purifies the water, the surface provides a resting place for birds, and the roots provide a substrate for fish eggs and larvae. The proportion of plant roots in the floating plant modules is calculated using the following formula: Where P represents the plant root filling ratio, and V r V represents the total volume of the plant's root system. m The total volume of the floating bed plant module is calculated based on the module's dimensions. The total volume of the plant root system is obtained by multiplying the average volume of a single plant root system by the number of plant roots in the module.
[0011] Pipe reef area: Located in the middle of the stainless steel frame structure and above the gabion cages, five PVC pipes of different diameters are placed in the 16 squares at the top of the frame, one set in each square, and fixed to the frame with nylon ropes. This area provides hiding and shelter for fish and aquatic organisms. Attached organisms can live on the pipe walls. The density of the pores on the PVC pipes is calculated using the following formula: Where D is the pore distribution density, n is the number of pores on a single PVC pipe, r is the radius of the PVC pipe, and L is the length of the PVC pipe. The number of pores on a single PVC pipe is set according to the ecological function requirements of PVC pipes of different diameters.
[0012] Gabion cage area: A gabion cage area is set at the bottom of the stainless steel frame device. Individual wire mesh cages are made, each filled with stones of different sizes, with four cages of each size, for a total of 16 cages. These cages are randomly placed into the 16 small squares at the bottom of the frame device. The frame is equipped with removable crossbars. The gabions provide a suitable habitat for shrimp, crabs, and various benthic organisms. The filling layout of stones of different sizes in the gabions uses a layered random filling algorithm. The specific steps are as follows: First, the gabion cage is divided into several small units. For each size of stone, a small unit is randomly selected for filling. The filling ratio of different sizes of stones in the gabion cage is calculated according to the following formula: Where R i N represents the filling ratio of the i-th type of stone. i N represents the number of stones of the i-th specification. t This refers to the total number of stones in the gabion cage. The number of stones is determined based on the cage volume, stone specifications, and the habitat requirements of the organisms.
[0013] Stainless steel frame structure: A stainless steel welded frame serves as the fixing device, with a welded steel plate at the bottom as the base to prevent it from sinking into sediment. Steel pipes are welded horizontally and vertically at heights of 0.25m and 0.75m, spaced 50cm apart, forming 16 small squares of 50cm x 50cm. The entire frame is anchored with nylon ropes around its perimeter, securing the device in the intertidal zone of the estuary to prevent it from being washed away by extreme weather such as typhoons. The welding process of the frame adopts an interlaced welding method. First, the horizontal and vertical steel pipes are spot-welded at each intersection. Then, starting from one corner of the frame, continuous welding is carried out in a specific order. After welding a certain distance, an intersection is skipped before continuing welding. This welding sequence was determined by stress analysis of the frame under the impact of water flow and wind waves. Simulation experiments have verified that this effectively improves the impact resistance of the frame.
[0014] Furthermore, the selection of plant roots in the floating bed plant module is based on the water quality conditions and biological attachment requirements of the intertidal zone of the estuary, specifically:
[0015] Ecological function analysis was conducted on the root systems of common intertidal aquatic plants in estuaries, including their ability to absorb nitrogen and phosphorus nutrients from the water and their stability in providing attachment sites for fish eggs and larvae. An evaluation model for the ecological function of plant roots was established, with evaluation indicators including root surface area, root hair density, and secretion composition. Data for each evaluation indicator was obtained through field sampling and laboratory analysis of various plant root systems. The weight of each evaluation indicator was determined using the analytic hierarchy process (AHP), for example, root surface area had a weight of 0.4, root hair density had a weight of 0.3, and secretion composition had a weight of 0.3. The comprehensive ecological function value of each plant root system was calculated based on the evaluation model. Plant root combinations with higher comprehensive ecological function values were selected for use in floating bed plant modules. The combination method was tailored to the characteristics of different plant root systems; for example, roots with strong adsorption capacity were combined with structurally stable roots to improve the overall performance of the floating bed plant modules.
[0016] Furthermore, the method for selecting the material and determining the diameter of the PVC pipe is as follows:
[0017] Corrosion resistance, strength, and biocompatibility tests were conducted on pipes of different materials. Pipe samples of different materials were placed in a simulated intertidal environment of the estuary, and changes in the physical properties of the pipes were periodically monitored. Simultaneously, the attachment and growth of organisms on the pipe surface were observed. After long-term testing and comparison, it was found that PVC material exhibits a relatively balanced performance in terms of corrosion resistance, strength, and biocompatibility, making it suitable as a material for pipe reefs. Regarding the determination of pipe diameter specifications, a study of the body size distribution of estuarine fish and other aquatic organisms was conducted. Cluster analysis was used to classify organisms into different categories based on their size distribution. The number of PVC pipes with different diameters was determined according to the proportion of each category of organisms and their space requirements. For example, for fish that are numerous and small, PVC pipes with diameters of φ5cm and φ10cm were more commonly selected. For larger fish or organisms requiring larger hiding spaces, PVC pipes with diameters of φ20cm and φ25cm were appropriately configured to meet the habitat needs of different organisms.
[0018] Furthermore, the weaving structure and mesh size design of the wire cage in the gabion box are as follows:
[0019] The wire mesh cage adopts a double-twisted hexagonal braided structure, which has high stability and strength. During the weaving process, the twisting angle of the wire is precisely calculated, and the twisting angle α is determined according to the following formula: Where d is the diameter of the lead wire and h is the vertical distance between adjacent lead wires. By adjusting the lead wire diameter and vertical distance, the twisting angle is optimized to ensure that the wire cage is not easily deformed under the impact of water flow. The mesh size is designed according to the size of the target benthic organisms. A dynamic adaptive mesh size algorithm is adopted. First, the body size data of common benthic organisms in the estuary are statistically analyzed to obtain the distribution range of organism body size. According to the distribution of organism body size, the mesh size is divided into multiple levels, each level corresponding to a certain range of organism body size. In the initial stage of device installation, a larger mesh size is used so that small benthic organisms can enter and exit freely. As time goes by, the mesh size is gradually adjusted according to the development of the biological community so that the mesh size always adapts to the growth and habitat needs of the organisms.
[0020] Furthermore, the connection method between the device frame and the anchor is as follows:
[0021] The frame and anchor are connected by adjustable-length nylon ropes. One end of the nylon rope is fixed to a specific position on the frame via a special buckle structure. This buckle structure ensures that the nylon rope will not fall off under tension and facilitates installation and disassembly. The other end of the nylon rope is connected to the anchor. The shape and weight of the anchor are designed according to the bottom conditions of the intertidal zone of the estuary. For silty bottoms, flat anchors are used, which have a larger area and can provide greater mechanical force. For sandy bottoms, claw anchors are used, whose claws can penetrate deep into the sand layer to enhance the anchoring effect. The length of the nylon rope can be adjusted from 3m to 5m. The adjustment mechanism is based on real-time monitoring of tidal level changes and water flow impact force. After the device is installed, sensors installed on the frame monitor the tidal level and water flow impact force, and automatically adjust the length of the nylon rope according to the monitoring data to keep the device stable under different water level and flow conditions.
[0022] Furthermore, the buoyancy adjustment method for the foam floats of the plant floating bed is as follows:
[0023] The foam pontoon employs a partitioned structure, divided into multiple independent air chambers. Each chamber is equipped with an adjustable air pressure valve, which controls the entry and exit of gas, thereby regulating the buoyancy of the foam pontoon. Buoyancy adjustment is based on a balance calculation between the overall weight of the device and tidal buoyancy. First, the total weight W of the plant floating bed, pipe reef, gabion cage, and attached organisms is measured. t Based on the density ρ of the tide and the submerged volume V of the device in the tide. i Calculate the required buoyancy F b =ρgV i Where g is the acceleration due to gravity, by adjusting the air pressure in the air chamber of the foam float, the buoyancy provided by the foam float is equal to or slightly greater than the required buoyancy, ensuring that the plant floating bed can float smoothly up and down with the tide, and will not detach from the frame due to excessive buoyancy under extreme weather conditions.
[0024] Furthermore, the fixed angle and height of the PVC pipe on the frame in the pipeline reef are set as follows:
[0025] The fixing angle of the PVC pipe on the frame is optimized according to the estuary water flow direction and lighting conditions. Through long-term monitoring of the estuary water flow direction, the main flow direction and velocity variation patterns are obtained. The PVC pipe is fixed on the frame at a certain angle θ with the water flow direction. The value of θ ranges from 30° to 60°. This angle setting can generate turbulence when the water flows through the PVC pipe, increasing the oxygen content in the water and facilitating the entry and exit of organisms into the pipe chamber. As for lighting conditions, the height of the PVC pipe is adjusted according to the sunshine duration and solar altitude angle changes in the estuary area, so that the PVC pipe can obtain suitable lighting in different seasons and times, promoting the growth of organisms attached to the pipe wall. The height adjustment is achieved by setting a movable fixing device on the frame, which can precisely adjust the height of the PVC pipe according to actual needs.
[0026] Furthermore, the surface treatment method for the stones in the gabion cage is as follows:
[0027] The stone surface is treated with a biocompatible coating. The coating material is a mixture of natural biological materials and organic binders. The natural biological materials include shell powder and coral powder, which are rich in calcium and magnesium. The coating preparation process involves mixing the natural biological materials and organic binders in a certain proportion, and then applying the coating evenly to the stone surface by spraying or dipping. The coating thickness is calculated using the following formula: Where T is the coating thickness, m is the mass of the coating per unit area, and ρ c S represents the density of the coating material, and S represents the surface area of the stone. The mass of the coating per unit area is determined based on the growth requirements of the attached organisms and the performance of the coating material. Through experimental research, the effects of coatings of different thicknesses on the growth of attached organisms are studied to select the optimal coating thickness, thereby increasing the attractiveness of the stones to shrimp, crabs, and benthic organisms and promoting their habitat and reproduction in the gabion cages.
[0028] On the other hand, the method for investigating and assessing estuarine fishery habitat restoration is characterized by the following specific steps:
[0029] S1. Sampling time determination: The first survey and assessment will begin one month after the remediation device is installed. Subsequent assessment intervals will be determined based on the seasonal variation patterns and biological growth cycles of the estuarine ecosystem. Regular surveys and sampling will be arranged in spring, summer, autumn and winter. This sampling time arrangement can comprehensively reflect the impact of the remediation device on various aquatic organisms in the estuary in different seasons.
[0030] S2, Sampling Area Division: The area where the remediation device is located is divided into multiple sub-areas. Each sub-area includes a part of the plant floating bed area, the pipe reef area, and the gabion cage area. At the same time, control sub-areas are divided in the nearby mudflats according to the same area and shape. The division of sub-areas is carried out using geographic information system technology, based on the topography and geomorphological features of the device and the mudflats, to ensure that each sub-area is representative and that the sub-areas of the remediation area and the control area are comparable in terms of environmental conditions.
[0031] S3, Sampling method:
[0032] Gabion cage sampling: A certain proportion of gabion cages in each sub-region were selected for sampling using a random stratified sampling method. For gabion cages with different sizes of stones, samples were collected from the upper, middle, and lower layers. Benthic animals and all aquatic organisms such as barnacles and oysters attached to the stones were collected into sample bottles. Sampling tools were used during the sampling process to reach different locations inside the gabion cages, avoiding damage to the organisms and ensuring that the collected samples were comprehensive.
[0033] Pipeline reef sampling: In the pipeline reef of each sub-region, several groups of PVC pipes are randomly selected for sampling. For each group of PVC pipes, biological samples are collected from the inlet, middle and outlet. All organisms in the PVC pipes are collected into sample bottles. During sampling, a gentle flushing method is used to flush the organisms out of the pipes, while avoiding flushing away small organisms or damaging biological tissues.
[0034] Plant floating bed sampling: In each sub-region of the plant floating bed, the height, density, and coverage area of the above-ground plants were first measured using non-destructive measurement methods. Then, a certain number of modules were selected from the floating bed plant modules for destructive sampling using an equidistant sampling method. The samples were collected as a whole and placed in a sorting box. During control sampling, 50cm×50cm×50cm sediment samples were collected in the control sub-region. A stratified sampling method was used to collect sediments from the surface, middle and deep layers. After rinsing through a 0.5mm sieve, aquatic organism samples were collected.
[0035] S4, Sample Processing and Analysis: All collected samples were brought back to the laboratory. For the plant floating bed samples, the aboveground parts and root system were carefully separated. The dry and wet weights were measured using a high-precision balance. At the same time, the chemical composition of the plant tissues was analyzed to detect the content of nutrients and heavy metals. For other aquatic organism samples, they were first classified and screened to remove impurities. Then, species identification was carried out using a combination of morphological and molecular biological identification methods. For the identified organisms, their individual size, weight and biological parameters were measured using precision measuring instruments.
[0036] S5, Data Processing and Evaluation Index Calculation: Establish a dedicated database to input and manage the collected and analyzed data, and calculate various evaluation indicators, including species richness (S), biomass quantity (N), and biomass density (D). b The Shannon-Wiener biodiversity index (H) is derived from the number of species identified statistically. Species richness is the total number of individuals of each species, while species density is calculated based on the area of the sampling region and the number of individuals. Where p i Let be the proportion of individuals of the i-th species to the total number of individuals. By comparing the differences in these indicators between the restoration area and the control area, the restoration effect of the restoration device on the estuarine fishery habitat is evaluated.
[0037] Compared with existing technologies, this three-dimensional device for estuarine fishery habitat restoration and its survey and assessment methods have the following advantages:
[0038] I. This invention constructs a three-dimensional restoration device comprising a floating plant bed area, a pipe reef area, and a gabion cage area, providing diverse habitats for different types of aquatic organisms. The floating plant bed area not only purifies the water but also provides a resting place for birds, while its root system provides an attachment substrate for fish eggs and larvae. The pipe reef area provides hiding and shelter for fish and other aquatic organisms, and attached organisms such as oysters and barnacles can grow on the pipe walls. The gabion cage area provides a suitable habitat for shrimp, crabs, and various benthic organisms. This three-dimensional habitat restoration device helps to improve the ecological diversity of estuarine fishery habitats, provides better habitat conditions for various aquatic organisms, and thus maintains ecological balance.
[0039] Second, this invention, through scientific and reasonable determination of sampling time, division of sampling area, sampling method, and sample processing and analysis steps, can comprehensively and accurately evaluate the restoration effect of the restoration device on estuarine fishery habitat. By comparing the species richness, number of organisms, density of organisms, and biodiversity index of the restoration area and the control area, the effect of the restoration device can be quantitatively evaluated. At the same time, the method can also continuously optimize and improve the restoration device based on the evaluation results to further enhance its ecological restoration effect. This precise evaluation and continuous optimization mechanism helps to promote the scientific and standardized process of estuarine fishery habitat restoration.
[0040] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description
[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.
[0042] Figure 1. Schematic diagram of a three-dimensional device for fishery habitat restoration;
[0043] Figure 2. Schematic diagram of the pipeline reef;
[0044] Figure 3. Schematic diagram of gabion cages;
[0045] Figure 4. Schematic diagram of plant floating bed;
[0046] Figure 5 is a flowchart of the estuarine fishery habitat restoration survey and assessment method.
[0047] In the diagram: 1. Floating plant bed; 2. Pipe reef; 201. Stainless steel frame; 202. PVC pipe; 203. First nylon rope; 204. Hole in the PVC pipe; 3. Gabion cage; 301. Stainless steel frame; 302. Wire cage; 303. Stones; 4. Anchor; 5. Stainless steel frame structure; 6. Second nylon rope; 7. Floating plant bed; 701. Foam float; 702. Angle iron; 703. Screw holes on the angle iron for fixing the floating bed; 704. Plant roots; 705. Polyethylene mesh. Detailed Implementation
[0048] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.
[0049] Example 1
[0050] This embodiment describes a small estuary area where fishery resources are gradually decreasing due to water pollution and habitat destruction. The intertidal current in this estuary is relatively slow, the bottom sediment is mainly silty, and there are certain human activities affecting the surrounding area, such as small-scale industrial emissions and agricultural non-point source pollution.
[0051] Based on the estuary water quality and biological needs, reed and calamus root systems were selected to form floating bed plant modules. The average volume of a single plant root and the number of plant roots in the module were measured to calculate the total volume of the plant roots. Then, based on the module dimensions, the total volume was determined. The plant root filling ratio was set at 60% according to the following formula: Where P represents the plant root filling ratio, and V r V represents the total volume of the plant's root system. mThe overall volume of the floating bed plant module is determined by the partitioned structure of the foam floats. The air pressure in the air chamber is adjusted to balance the buoyancy with the weight of the device, ensuring that the floating bed floats smoothly with the tide.
[0052] After material testing, PVC pipes were selected as the material for the pipe reef. After studying the body size distribution of fish in the estuary, it was determined that PVC pipes with diameters of 10cm, 15cm, and 20cm would be used, with 6, 5, and 4 pipes respectively. At a height of 0.5m, the PVC pipes were fixed to the frame at a 45° angle to the direction of water flow, so that they could generate turbulence to increase oxygen and facilitate the entry and exit of organisms. The number of holes on a single PVC pipe was set according to the pipe diameter and ecological function requirements, and the hole distribution density was reasonably distributed after calculation.
[0053] The gabion cages use a double-twisted hexagonal woven structure with 3mm diameter wire and a 5mm vertical distance between adjacent wires. The twisting angle is calculated as α = arctan(3 / 5). The initial mesh size is set at 5cm × 5cm, and adjusted according to the development of the biological community. Each gabion is filled with three sizes of stones: 5cm-10cm, 10cm-15cm, and 15cm-20cm. Four gabions are filled with each size, for a total of 16 gabions. The formula for calculating the filling ratio of different stone sizes is: Where R i N represents the filling ratio of the i-th type of stone. i N represents the number of stones of the i-th specification. t The total number of stones in the gabion cage is determined by a layered random filling algorithm, which is used to place the stones into the lower squares of the frame.
[0054] The bottom of the stainless steel frame is welded with steel plates, and steel pipes are welded horizontally and vertically at heights of 0.25m and 0.75m at intervals of 50cm to form 16 small squares. The staggered welding method is used to improve the impact resistance. The frame is connected to the flat anchor with nylon ropes around its perimeter. The length of the nylon ropes can be adjusted in real time according to the changes in tidal water level and water flow impact force, and can be adjusted within the range of 3m-5m.
[0055] One month after the repair device was installed, the first survey and assessment was conducted when the water temperature rose in the spring. Subsequent sampling was carried out according to specific seasonal periods: the peak growth period of organisms in summer, the period after the reproduction period of organisms in autumn, and the period before the organisms entered dormancy in winter.
[0056] Using geographic information system technology, the area where the restoration device is located is divided into four sub-regions. Each sub-region includes a part of a floating plant bed area, a pipe reef area, and a gabion cage area. At the same time, a control sub-region of the same area and shape is divided in the nearby mudflats.
[0057] 30% of the gabion cages in each sub-region were randomly selected by layer, and samples were collected from the upper, middle and lower layers of gabion cages of different sizes. Benthic animals and attached organisms were collected using specialized sampling tools.
[0058] Three sets of PVC pipes were randomly selected from the pipeline reef in each sub-region, and biological samples were collected from the inlet, middle and outlet. The organisms inside the pipes were gently rinsed.
[0059] The height, density, and coverage area of the above-ground plants on the floating plant bed were measured. Ten floating plant modules were randomly selected at equal intervals for destructive sampling, and the samples were collected and placed in a sorting box. Sediment samples of 50cm×50cm×50cm were collected from the control area. After stratified sampling, aquatic organism samples were collected by rinsing through a 0.5mm sieve.
[0060] The samples were brought back to the laboratory. The aboveground and root parts of the plant floating bed samples were separated and their dry and wet weights were measured and their chemical composition was analyzed. Other aquatic biological samples were classified, screened, and impurities were removed. The species were identified by morphology and molecular biology, and the biological parameters of individual size and weight were measured with precision instruments.
[0061] Establish a database, input data, and calculate biodiversity, abundance, density, and Shannon-Wiener index assessment indicators. Where p i The proportion of individuals of the i-th species to the total number of individuals is used to assess the restoration effect by comparing the differences between the restoration area and the control area.
[0062] Example 2
[0063] This embodiment describes a river estuary area where, due to the construction of various water conservancy projects such as tidal flat reclamation, the intertidal zone aquatic organisms have suffered severe habitat loss, the number of fish and benthic organisms has decreased significantly, and the aquatic ecosystem has become unbalanced.
[0064] Select reeds with well-developed root systems to fill the floating bed plant modules. The floating bed plant modules are placed on the upper grid of the stainless steel frame and fixed with angle iron, screws and nylon ropes. Foam floats around the perimeter adjust the buoyancy to ensure that the floating bed floats steadily with the tide.
[0065] PVC pipes were selected based on material testing. The pipe diameter was determined to be primarily small to medium diameter based on the body size distribution of fish in the estuary (mostly small to medium-sized fish). The PVC pipes were fixed to the upper grid of the frame at a specific angle (45° to the water flow direction) and height (adjusted according to sunlight). The density of the holes was calculated based on ecological function requirements, using the following formula: Where D is the pore distribution density, n is the number of pores on a single PVC pipe, r is the radius of the PVC pipe, and L is the length of the PVC pipe, providing a good environment for fish and attached organisms.
[0066] The wire cage uses a double-twisted hexagonal woven structure with an initial relatively large mesh size, which is subsequently adjusted based on the growth of benthic organisms. The stones are treated with a biocompatible coating and then filled with stones of different sizes using a layered random filling algorithm. The formula is as follows: Where R i N represents the filling ratio of the i-th type of stone. i N represents the number of stones of the i-th specification. t This refers to the total number of stones in the gabion cage, which is placed in the squares at the bottom of the frame to provide a habitat for shrimp, crabs, and benthic organisms.
[0067] The stainless steel frame uses an interlaced welding process, with horizontal and vertical steel pipes welded at intervals to form a grid. A steel plate base is welded to the bottom, and the surrounding area is connected to a flat anchor suitable for the bottom (silty) by adjustable nylon ropes. The length of the nylon ropes is adjusted according to the monitoring data of tidal water level and water flow impact force to fix the device in the intertidal zone of the estuary.
[0068] One month after the device was installed, the sampling time was determined according to the seasonal characteristics. The geographic information system was used to divide the restoration device and the nearby mudflats into multiple sub-regions to ensure that the restoration area and the control area were comparable.
[0069] Samples were collected from the plant floating beds, pipe reefs, gabion cages, and control areas using their respective sampling methods. These samples were then brought back to the laboratory for processing and analysis, including plant weight and composition analysis, biological classification, identification, and parameter measurement.
[0070] Data processing and evaluation indicators show that the species richness, quantity, density, and diversity index of the restored area are significantly higher than those of the control area, and the number of fish and benthic organisms is gradually increasing. This indicates that the device can provide suitable habitats for various swimming and benthic animals in the estuary and has a significant effect on the restoration of estuarine fishery habitats.
[0071] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create similar embodiments without departing from the scope of the present invention. Any simple modifications, similar changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.
Claims
1. A three-dimensional device for estuarine fishery habitat restoration, characterized in that, The device includes a plant floating bed area (7), a pipe reef area (2), a gabion cage area (3), and a stainless steel frame structure (5); The plant floating bed area (7) includes: foam float (701), angle iron (702), screw holes (703) on the angle iron for fixing the floating bed, plant roots (704), and polyethylene mesh (705). The pipeline reef area (2) includes: a stainless steel frame (201), a PVC pipe (202), a first nylon rope (203), and a hole (204) in the PVC pipe; The gabion area (3) includes: a stainless steel frame (301), a wire mesh cage (302), and stones (303); Plant floating bed area (7): Located on the upper part of the stainless steel frame (201) device, it consists of foam floats (701), stainless steel pipe frame and floating bed plant modules. The upper part of the stainless steel frame (201) is welded into 9 squares by angle iron (703). Each square holds a floating bed plant module. The module is fixed to the frame by screws through the holes on the angle iron (703). The floating bed plant module consists of two layers of polyethylene mesh (706) and plant roots (705) filled in the middle. It is clamped and tied with plastic cable ties. The entire floating bed frame is nested in the stainless steel frame (201) and located at the top of the frame. It is connected to the frame by nylon rope (203). The foam floats (701) around the perimeter allow the floating bed to float up and down with the tide without falling off the frame. Plant growth can purify the water. The surface of the floating bed provides a resting place for birds. The roots provide an attachment substrate for fish eggs and larvae. The filling ratio of plant roots (705) in the floating bed plant module is determined by the following formula: Where P is the filling ratio of plant roots (705), V r V represents the total volume of the plant root system (705). m The total volume of the floating bed plant module is calculated based on the size of the module. The total volume of the plant root system (705) is obtained by measuring the average volume of a single plant root system (705) and the number of plant roots (705) in the module. Pipe reef area (2): Located in the middle of the stainless steel frame (201) device and above the gabion cage, five PVC pipes (202) of different diameters are placed in the 16 squares at the top of the frame, one set in each square, and fixed to the frame with nylon rope (203). This area can provide a hiding and shelter place for fish and aquatic organisms. Attached organisms can grow on the pipe wall. The density of the holes on the PVC pipe (202) is calculated according to the following formula: Where D is the pore distribution density, n is the number of pores on a single PVC pipe (202), r is the radius of the PVC pipe (202), and L is the length of the PVC pipe (202). The number of pores on a single PVC pipe (202) is set according to the ecological function requirements of PVC pipes (202) with different pipe diameters. Gabion cage area (3): A gabion cage area (3) is set at the bottom of the stainless steel frame (201) device. Independent cages are made of wire mesh (302). Each cage is filled with stones (303) of different specifications. Four cages are filled with each specification, for a total of 16 cages. They are randomly placed into 16 small squares at the bottom of the frame device. The frame is equipped with detachable crossbars. The cage provides a suitable habitat for shrimp, crabs and various benthic organisms. The filling layout of stones (302) of different specifications in the gabion cage adopts a layered random filling algorithm. The specific steps are as follows: First, the gabion cage is divided into several small units of equal volume. For each specification of stone (302), a small unit is randomly selected for filling. The filling ratio of stones (302) of different specifications in the gabion cage is calculated according to the following formula: Where R i N represents the filling ratio of the i-th type of stone (302). i N represents the number of stones of the i-th specification (302). t The total number of stones (302) in the gabion cage is determined based on the cage volume, stone (302) specifications, and habitat requirements of organisms. Stainless steel frame structure (5): A stainless steel welded frame is used as a fixing device. A steel plate is welded at the bottom as a base to prevent it from sinking into sediment. Steel pipes are welded horizontally and vertically at heights of 0.25m and 0.75m with a spacing of 50cm to form 16 small squares of 50cm×50cm. The entire frame is connected to anchors (4) with nylon ropes (203) around it to fix the device in the intertidal zone of the estuary to prevent it from being washed away by extreme weather such as typhoons. The welding process of the frame adopts an interlaced welding method. First, the horizontal steel pipes and vertical steel pipes are spot welded and fixed at each intersection. Then, starting from one corner of the frame, continuous welding is carried out in a specific order. After welding a certain distance, an intersection is skipped and welding continues. This welding sequence is determined by analyzing the stress of the frame under the impact of water flow and wind waves. The simulation experiment has verified that it can effectively improve the impact resistance of the frame.
2. The three-dimensional device for estuarine fishery habitat restoration according to claim 1, characterized in that, The selection of plant roots (705) in the floating bed plant module is based on the water quality conditions and biological attachment requirements of the intertidal zone of the estuary, specifically: Ecological function analysis was conducted on the root systems (705) of common aquatic plants in the intertidal zone of estuaries, including their ability to absorb nitrogen and phosphorus nutrients in the water and their stability in providing attachment for fish eggs and larvae. An ecological function evaluation model for plant roots (705) was established, with evaluation indicators including root surface area, root hair density, and secretion composition. Data for each evaluation indicator was obtained through field sampling and laboratory analysis of various plant roots (705). The weight of each evaluation indicator was determined using the analytic hierarchy process (AHP). The comprehensive ecological function value of each plant root system (705) was calculated based on the evaluation model. Plant root systems (705) with higher comprehensive ecological function values were selected for use in floating bed plant modules. The combination method was based on the characteristics of different plant roots (705).
3. The three-dimensional device for estuarine fishery habitat restoration according to claim 1, characterized in that, The method for selecting the material and determining the diameter of the PVC pipe (202) is as follows: Corrosion resistance, strength, and biocompatibility tests were conducted on pipes of different materials. Pipe samples of different materials were placed in a simulated intertidal environment of the estuary, and the changes in the physical properties of the pipes were regularly monitored. At the same time, the attachment and growth of organisms on the pipe surface were observed. After long-term testing and comparison, it was found that PVC material showed a relatively balanced performance in terms of corrosion resistance, strength, and biocompatibility, and was suitable as a material for pipe reefs. For the determination of pipe diameter specifications, the body size distribution of estuarine fish and other aquatic organisms was studied, and the body size of the organisms was divided into different categories using cluster analysis. Based on the proportion of each category of organisms and their activity space requirements, the number of PVC pipes (202) of different diameter specifications was determined.
4. The three-dimensional device for estuarine fishery habitat restoration according to claim 1, characterized in that, The weaving structure and mesh size design of the wire mesh cage (302) in the gabion cage are as follows: The wire mesh cage (302) adopts a double-twisted hexagonal braided structure, which has high stability and strength. During the weaving process, the twisting angle of the wire is precisely calculated, and the twisting angle α is determined according to the following formula: Where d is the diameter of the lead wire and h is the vertical distance between adjacent lead wires. By adjusting the lead wire diameter and vertical distance, the twisting angle is optimized. The mesh size is designed according to the body size of the target benthic organisms. A dynamic adaptive mesh size algorithm is adopted. First, the body size data of common benthic organisms in the estuary are statistically analyzed to obtain the distribution range of organism body size. According to the distribution of organism body size, the mesh size is divided into multiple levels, each level corresponding to a certain range of organism body size. In the initial stage of device installation, a larger mesh size is used. According to the development of the biological community, the mesh size is gradually adjusted so that the mesh size always adapts to the growth and habitat needs of the organisms.
5. The three-dimensional device for estuarine fishery habitat restoration according to claim 1, characterized in that, The connection method between the device frame and the anchor (4) is as follows: An adjustable-length nylon rope (203) is used to connect the frame and the anchor (4). One end of the nylon rope (203) is fixed to a specific position on the frame by a special buckle structure. The buckle structure can ensure that the nylon rope (203) will not fall off when subjected to tension and is easy to install and disassemble. The other end of the nylon rope (203) is connected to the anchor (4). The shape and weight of the anchor (4) are designed according to the bottom conditions of the intertidal zone of the estuary. For silty bottom, a flat anchor (4) is used, which has a larger area and can provide greater mechanical force. For sandy bottom, a claw anchor (4) is used, whose claw can penetrate into the sand layer to enhance the anchoring effect. The length of the nylon rope (203) can be adjusted from 3m to 5m. The adjustment mechanism is based on the real-time monitoring of tidal water level changes and water flow impact force. After the device is installed, the tidal water level and water flow impact force are monitored by sensors installed on the frame. The length of the nylon rope (203) is automatically adjusted according to the monitoring data to keep the device stable under different water levels and water flow conditions.
6. The three-dimensional device for estuarine fishery habitat restoration according to claim 1, characterized in that, The buoyancy adjustment method for the foam float (701) of the plant floating bed is as follows: The foam float (701) has a partitioned internal structure, divided into multiple independent air chambers. Each air chamber is equipped with an adjustable air pressure valve, which controls the entry and exit of gas within the chamber, thereby adjusting the buoyancy of the foam float (701). The buoyancy adjustment is based on a balance calculation of the overall weight of the device and the tidal buoyancy. First, the total weight W of the plant floating bed, pipe reef, gabion cage, and attached organisms is measured. t Based on the density ρ of the tide and the submerged volume V of the device in the tide. i Calculate the required buoyancy F b =ρgV i Where g is the acceleration due to gravity, by adjusting the air pressure in the air chamber of the foam float (701), the buoyancy provided by the foam float (701) is equal to or slightly greater than the required buoyancy, ensuring that the plant floating bed can float up and down smoothly with the tide, and will not detach from the frame due to excessive buoyancy under extreme weather conditions.
7. The three-dimensional device for estuarine fishery habitat restoration according to claim 1, characterized in that, The fixed angle and height of the PVC pipe (202) in the pipeline reef on the frame are set as follows: The fixing angle of the PVC pipe (202) on the frame is optimized according to the direction of the estuary water flow and the lighting conditions. Through long-term monitoring of the direction of the estuary water flow, the main flow direction and velocity change law of the water flow are obtained. The PVC pipe (202) is fixed on the frame so that it forms a certain angle θ with the direction of the water flow. The value of θ is in the range of 30°-60°. This angle setting can make the water flow generate turbulence when passing through the PVC pipe (202), increase the oxygen content in the water, and facilitate the entry and exit of organisms in the pipe chamber. As for the lighting conditions, the height of the PVC pipe (202) is adjusted according to the sunshine time and solar altitude angle changes in the estuary area so that the PVC pipe (202) can obtain suitable lighting in different seasons and times, promoting the growth of organisms attached to the pipe wall. The height adjustment is achieved by setting a movable fixing device on the frame, and the height of the PVC pipe (202) can be precisely adjusted according to actual needs.
8. The three-dimensional device for estuarine fishery habitat restoration according to claim 1, characterized in that, The surface treatment method for the stones (302) in the gabion cage is as follows: The surface of the stone (302) is treated with a bio-compatible coating. The coating material is a mixture of natural biological materials and organic binders. The natural biological materials include shell powder and coral powder, which are rich in calcium and magnesium. The preparation process of the coating involves mixing the natural biological materials and organic binders in a certain proportion, and then applying the coating evenly to the surface of the stone (302) by spraying or immersion. The coating thickness is calculated and determined by the following formula: Where T is the coating thickness, m is the mass of the coating per unit area, and ρ c S is the density of the coating material, and S is the surface area of the stone (302).
9. A method for investigating and assessing estuarine fishery habitat restoration, characterized in that... The specific steps of this method are as follows: S1. Sampling time determination: The first survey and assessment will begin one month after the remediation device is installed. Subsequent assessment intervals will be determined based on the seasonal variation patterns and biological growth cycles of the estuarine ecosystem. Surveys and sampling will be arranged in spring, summer, autumn, and winter. This sampling time arrangement can comprehensively reflect the impact of the remediation device on various aquatic organisms in the estuary in different seasons. S2, Sampling area division: The area where the restoration device is located is divided into multiple sub-areas. Each sub-area includes a part of the plant floating bed area (7), the pipe reef area (2), and the gabion cage area (3). At the same time, control sub-areas are divided in the nearby mudflats according to the same area and shape. The division of sub-areas is carried out using geographic information system technology. The sub-areas are precisely divided according to the topography and geomorphological features of the device and the mudflats to ensure that each sub-area is representative and that the sub-areas of the restoration area and the control area are comparable in terms of environmental conditions. S3, Sampling method: Gabion cage sampling: A certain proportion of gabion cages in each sub-region were selected for sampling using a random stratified sampling method. For gabion cages with different sizes of stones (302), samples were collected from the upper, middle and lower layers respectively. Benthic animals and barnacles and oysters attached to the stones (302) were collected into sample bottles. Sampling tools were used during the sampling process to penetrate into different locations inside the gabion cage, avoiding damage to the organisms and ensuring that the collected samples were comprehensive. Pipeline reef sampling: In the pipeline reef of each sub-region, several groups of PVC pipes (202) were randomly selected for sampling. For each group of PVC pipes (202), biological samples were collected from the inlet, middle and outlet. All the organisms in the PVC pipes (202) were collected into sample bottles. During sampling, a gentle flushing method was used to flush the organisms out of the pipes, while avoiding flushing away small organisms or damaging biological tissues. Plant floating bed sampling: In each sub-region of the plant floating bed, the height, density, and coverage area of the above-ground plants were first measured using non-destructive measurement methods. Then, a certain number of modules were selected from the floating bed plant modules for destructive sampling using an equidistant sampling method. The samples were collected as a whole and placed in a sorting box. During control sampling, 50cm×50cm×50cm sediment samples were collected in the control sub-region. A stratified sampling method was used to collect sediments from the surface, middle and deep layers. After rinsing through a 0.5mm sieve, aquatic organism samples were collected. S4, Sample Processing and Analysis: All collected samples were brought back to the laboratory. For the plant floating bed samples, the aboveground parts and root system were carefully separated. The dry and wet weights were measured using a high-precision balance. At the same time, the chemical composition of the plant tissues was analyzed to detect the content of nutrients and heavy metals. For other aquatic organism samples, they were first classified and screened to remove impurities. Then, species identification was carried out using a combination of morphological and molecular biological identification methods. For the identified organisms, their individual size, weight and biological parameters were measured using precision measuring instruments. S5, Data Processing and Evaluation Index Calculation: Establish a dedicated database to input and manage the collected and analyzed data, and calculate various evaluation indicators, including species richness (S), biomass quantity (N), and biomass density (D). b The Shannon-Wiener biodiversity index (H) is derived from the number of species identified statistically. Species richness is the total number of individuals of each species, while species density is calculated based on the area of the sampling region and the number of individuals. Where p i Let be the proportion of individuals of the i-th species to the total number of individuals. By comparing the differences in these indicators between the restoration area and the control area, the restoration effect of the restoration device on the estuarine fishery habitat is evaluated.