Three-dimensional device for restoration of estuarine fishery habitats and its investigation and assessment method

Abstract

The present invention discloses a three-dimensional device for restoring estuarine fishery habitats and a survey and assessment method, relating to the technical field of fishery ecological restoration. The device comprises the following components: a plant floating bed area, a pipeline reef area, a gabion cage area and a device frame. The present invention provides a diverse habitat for different types of aquatic organisms by constructing a three-dimensional restoration device comprising the plant floating bed area, the pipeline reef area and the gabion cage area. The plant floating bed area can not only purify the water body, but also provide a resting place for birds. At the same time, its root system provides an attachment matrix for fish eggs and larvae. The pipeline reef area provides a hiding and shelter place for fish and other aquatic organisms. Attached organisms such as oysters and barnacles can grow on the pipe wall. The gabion cage area provides a suitable habitat for shrimps, crabs and various benthic organisms. This three-dimensional habitat restoration device helps to improve the ecological diversity of estuarine fishery habitats and provide better habitat conditions for various aquatic organisms.

Description

Technical Field

[0001] The present invention relates to the technical field of fishery ecological restoration, in particular to a three-dimensional device for restoring estuary fishery habitats and a survey and assessment method. Background Art

[0002] Estuarine fishery habitats are an important part of the ecosystem. They not only provide habitats for many aquatic organisms, but also play a key role in maintaining ecological balance and human fishery activities. However, with the continuous increase in human activities, the ecological environment in estuaries has been severely damaged, and 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 estuary fishery habitats through scientific methods.

[0003] Although traditional three-dimensional restoration devices can improve fishery habitats to a certain extent, they still have some obvious shortcomings. They lack comprehensive consideration of the habitat needs of different types of aquatic organisms. Although gabion cage areas can provide habitats for shrimps, crabs and benthic organisms, they lack flexibility and adaptability, especially in silted estuaries. It is easy for the cages to be silted up and lose their function of providing habitats, making it difficult to meet the needs of dynamically changing biological communities.

[0004] In summary, traditional fishery ecological restoration technology has certain limitations in the restoration of estuarine fishery habitats. In order to overcome these shortcomings, the present invention proposes a three-dimensional device for estuarine fishery habitat restoration and an investigation and evaluation method, which is particularly important. Summary of the Invention

[0005] The purpose of the present invention is to make up for the shortcomings of the existing technology and provide a three-dimensional device for restoring estuarine fishery habitats and an investigation and evaluation method. It can provide a diverse habitat for different types of aquatic organisms by constructing a three-dimensional restoration device including a plant floating bed area, a pipeline reef area and a gabion cage area, and accurately evaluate the restoration effect through a systematic investigation and evaluation method to achieve comprehensive restoration and improvement of the estuarine fishery habitat.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a three-dimensional device for restoring estuary fishery habitats, which includes a plant floating bed area, a pipeline reef area, a gabion cage area and a stainless steel frame structure (5):

[0007] The plant floating bed area (1) comprises: a foam float (701), an angle iron (702), screw holes (703) on the angle iron for fixing the floating bed, a plant root system (704), and a polyethylene mesh (705);

[0008] The pipeline reef area (2) comprises: a stainless steel frame (201), a PVC pipe (202), a first nylon rope (203), and a hole (204) opened on the PVC pipe;

[0009] The gabion box area (3) comprises: a stainless steel frame (301), a wire mesh cage (302), and stones (303);

[0010] Plant floating bed area: Located on the upper part of the stainless steel frame device, it consists of foam floats, stainless steel pipe frames and floating bed plant modules. The upper part of the stainless steel frame is welded into 9 squares by angle irons. A floating bed plant module is placed in each square. The module and the frame are fixed with screws through the holes on the angle irons. The floating bed plant module consists of two layers of polyethylene mesh and plant roots filled in the middle. It is clamped and fastened with plastic ties. The entire floating bed frame is nested in the stainless steel frame and located at the top of the frame. It is connected to the frame with nylon ropes. The foam floats around it enable the floating bed to float up and down with the tide without leaving the frame. Plant growth can purify the water. The floating bed surface provides a resting place for birds, and the roots provide an attachment matrix for fish eggs and larvae. The filling ratio of plant roots in the floating bed plant module is determined by the following formula: Where P is the filling ratio of plant roots, V r is the total volume of plant roots, V m is the total volume of the floating bed plant module. The total volume of the plant root system is obtained by measuring the product of the average volume of a single plant root and the number of plant roots in the module. The total volume of the floating bed plant module is calculated based on the size of the module.

[0011] Pipeline reef area: Located in the middle of the stainless steel frame device and above the gabion cage, five PVC pipes of different diameters are placed in the 16 squares on the upper part of the frame, one group in each square, and fixed to the frame with nylon rope. This area can provide a hiding place and shelter for fish and aquatic organisms, and attached organisms can grow on the pipe wall. The density of the hole distribution on the PVC pipe is calculated according to the following formula: Where D is the hole distribution density, n is the number of holes 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 holes on a single PVC pipe is set according to the ecological function requirements of PVC pipes of different diameters.

[0012] Gabion area: A gabion area is set up at the bottom of the stainless steel frame device. Independent cages are made of wire cages. Each cage is filled with stones of different sizes. Four cages of each size are filled, for a total of 16 cages. They are randomly placed in the 16 small squares at the bottom of the frame device. Removable cross bars are provided around the frame. The cages provide suitable habitats for shrimps, crabs and various benthic organisms. The filling layout of stones of different sizes in the gabion cages adopts a layered random filling algorithm. The specific steps are as follows: First, the gabion cage is divided into several small units of volume. For each size of stone, a small unit is randomly selected for filling. The filling ratio of stones of different sizes in the gabion cage is calculated according to the following formula: where R i is the filling ratio of the i-th specification stone, N i is the number of stones of the i-th specification, N t The total number of stones in the gabion cage is determined by the cage volume, stone specifications and biological habitat requirements;

[0013] Stainless steel frame structure: A stainless steel welded frame is used as a fixing device, and a steel plate is welded at the bottom as a base to prevent it from sinking into the sediment. Steel pipes are welded horizontally and vertically at heights of 0.25m and 0.75m with intervals of 50cm to form 16 small squares of 50cm×50cm. The entire frame is connected with anchors with nylon ropes on all sides to fix the device in the intertidal zone of the estuary to prevent it from being knocked down by extreme weather such as typhoons. The welding process of the frame adopts a staggered welding method. The horizontal and vertical steel pipes are first spot-welded at each intersection, and then starting from a corner of the frame, continuous welding is performed in a specific order. After each welding distance, an intersection is skipped and welding is continued. The determination of this welding sequence is based on the force analysis of the frame under the impact of water flow and wind and waves. It has been verified through simulation experiments that it can effectively improve 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] An ecological function analysis was conducted on the roots of common aquatic plants in the intertidal zone of estuaries, including their ability to absorb nitrogen and phosphorus nutrients in the water body and their stability in providing attachment for fish eggs and larvae. An ecological function evaluation model for plant roots was established. The evaluation indicators included root surface area, root hair density, and secretion composition. Through field sampling and laboratory analysis of the roots of various plants, data for various evaluation indicators were obtained. The hierarchical analysis method was used to determine the weight of each evaluation indicator. For example, the weight of root surface area was 0.4, the weight of root hair density was 0.3, and the weight of secretion composition was 0.3. The comprehensive ecological function value of each plant root was calculated according to the evaluation model, and plant root combinations with higher comprehensive ecological function values ​​were selected for the floating bed plant module. The combination method was matched according to the characteristics of different plant roots. For example, roots with strong adsorption capacity were combined with roots with stable structure to improve the overall performance of the floating bed plant module.

[0016] Furthermore, the material selection and pipe diameter specification determination method of the PVC pipe are as follows:

[0017] Pipes made of different materials were tested for corrosion resistance, strength, and biocompatibility. Pipe samples of different materials were placed in a simulated intertidal zone environment in the estuary. Changes in the physical properties of the pipes were regularly monitored, and the attachment and growth of organisms on the pipe surface were observed. After a long period of testing and comparison, it was found that PVC material showed a relatively balanced performance in terms of corrosion resistance, strength, and biocompatibility, making it suitable as a material for pipeline reefs. As for the determination of pipe diameter specifications, through the study of the body size distribution of estuarine fish and other aquatic organisms, the cluster analysis method was used to classify the body sizes of organisms into different categories. According to the number ratio of organisms in each category and the activity space requirements, the number of PVC pipes of different diameters was determined. For example, for fish with a large number and small size, PVC pipes with diameters of φ5cm and φ10cm are more commonly selected. For larger fish or organisms that require a larger hiding space, PVC pipes with diameters of φ20cm and φ25cm are appropriately configured to meet the habitat needs of different organisms.

[0018] Furthermore, the weaving structure and mesh size of the wire mesh cage in the gabion box are designed as follows:

[0019] The wire cage adopts a double-twisted hexagonal braided structure, which has high stability and strength. During the braiding process, the twist angle of the lead wire is accurately calculated, and the twist angle α is determined according to the following formula: Where d is the wire diameter, and h is the vertical distance between adjacent wires. By adjusting the 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 used. First, the body size data of common benthic organisms in the estuary are statistically analyzed to obtain the distribution range of the organism's size. According to the distribution of organism size, the mesh size is divided into multiple levels, and each level corresponds to a certain range of organism size. In the initial stage of device installation, a larger mesh size is used to allow small benthic organisms to enter and exit freely. Over time, according to the development of the biological community, the mesh size is gradually adjusted to ensure that the mesh size always adapts to the growth and habitat needs of the organisms.

[0020] Furthermore, the device frame and the anchor are connected in the following manner:

[0021] An adjustable-length nylon rope is used to connect the frame and the anchor. One end of the nylon rope is fixed to a specific position on the frame through a special buckle structure. The buckle structure can ensure that the nylon rope will not fall off when subjected to tension and is easy to install and disassemble. 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 muddy bottoms, a flat anchor is used, which has a larger area and can provide greater mechanical strength. For sandy bottoms, a claw anchor is used, whose claws can penetrate into the sand layer to enhance the anchoring effect. The length of the nylon rope can be adjusted in the range of 3m-5m. The adjustment mechanism is based on 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, and the length of the nylon rope is automatically adjusted according to the monitoring data to keep the device stable under different water levels and water flow conditions.

[0022] Furthermore, the buoyancy adjustment method of the foam float of the plant floating bed is:

[0023] The interior of the foam float adopts a partitioned structure, which is divided into multiple independent air chambers. Each air chamber is equipped with a valve that can adjust the air pressure. The valve can control the inflow and outflow of the air in the air chamber, thereby adjusting the buoyancy of the foam float. The buoyancy adjustment is based on the balance calculation of the overall weight of the device and the buoyancy of the tide. First, the total weight W of the plant floating bed, pipeline reef, gabion cage and attached organisms is measured. t According to the density of tidal water ρ and the submerged volume V of the device in tidal water i , calculate the required buoyancy F b =ρgV i , where g is the acceleration due to gravity. By adjusting the air pressure in the foam float chamber, 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 up and down smoothly with the tide and will not fall off the frame due to excessive buoyancy under extreme weather conditions.

[0024] Furthermore, the fixed angle and height of the PVC pipe in the pipeline reef on the frame are set as follows:

[0025] The fixing angle of the PVC pipe on the frame is optimized according to the direction of the estuary water flow and the lighting conditions. Through long-term monitoring of the estuary water flow direction, the main flow direction and flow rate change pattern of the water flow are obtained, and the PVC pipe is fixed on the frame so that it forms a certain angle θ with the water flow direction. The value range of θ is 30°-60°. This angle setting can cause turbulence when the water flows through the PVC pipe, increase the oxygen content in the water, and facilitate the entry and exit of organisms into the pipe warehouse. As for the lighting conditions, the height of the PVC pipe is adjusted according to the changes in sunshine time and solar altitude angle in the estuary area, so that the PVC pipe can obtain appropriate light 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 can be precisely adjusted according to actual needs.

[0026] Furthermore, the surface treatment method of the stones in the gabion box is:

[0027] The stone surface is treated with a bio-affinity coating. The coating material is a mixture of natural biological materials and organic binders. Natural biological materials include shell powder and coral powder, which are rich in calcium and magnesium. The coating preparation process includes mixing the natural biological materials and organic binders in a certain proportion. The coating is evenly covered on the stone surface 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 is the density of the coating material, S is the surface area of ​​the stone, and the mass of the coating per unit area is determined according to the growth requirements of the attached organisms and the performance of the coating material. Through experimental research on the effects of coatings of different thicknesses on the growth of attached organisms, the optimal coating thickness is selected to increase the attractiveness of stones to shrimps, crabs and benthic organisms, and promote the habitation and reproduction of organisms in gabions.

[0028] On the other hand, the estuarine fishery habitat restoration investigation and assessment method is characterized in that the specific steps of the method are:

[0029] S1. Determination of sampling time: The first survey and assessment will begin one month after the restoration device is installed. The intervals for subsequent assessments will be determined based on the seasonal changes in the estuarine ecosystem and the biological growth cycle. Regular surveys and sampling will be arranged in spring, summer, autumn, and winter. This sampling schedule can fully reflect the effects of the restoration device on various aquatic organisms in the estuary in different seasons.

[0030] S2. Sampling area division: The area where the restoration device is located is divided into multiple sub-areas. Each sub-area includes a plant floating bed area, a pipeline reef area, and a portion of a gabion cage area. A control sub-area of ​​the same size and shape is also established on the nearby mudflats. Geographic information system technology is used to accurately divide the sub-areas based on the topographic and geomorphological characteristics of the device and mudflats to ensure that each sub-area is representative and that the environmental conditions of the sub-areas in the restoration and control areas are comparable.

[0031] S3, sampling method:

[0032] Gabion cage sampling: From the gabion cages in each sub-area, a certain proportion of the cages were selected for sampling according to the random stratified sampling method. For cages with stones of different specifications, samples were collected from the upper, middle and lower layers. All aquatic organisms, including benthic animals and barnacles and oysters attached to the stones, were collected into sample bottles. The sampling process used sampling tools that could penetrate into different locations inside the cages to avoid damage to the organisms and ensure that the collected samples were comprehensive.

[0033] Pipeline reef sampling: Randomly select several groups of PVC pipes from the pipeline reefs in each sub-area for sampling. For each group of PVC pipes, collect biological samples from the inlet, middle, and outlet. Collect all organisms in the PVC pipes into sample bottles. During sampling, use a gentle flushing method to flush the organisms out of the pipes while avoiding washing away small organisms or damaging biological tissues.

[0034] Plant floating bed sampling: In each sub-area of ​​the plant floating bed, first measure the height, density, and coverage area growth indicators of the above-ground plants using non-destructive measurement methods. Then, select a certain number of modules from the floating bed plant modules according to the equidistant sampling method for destructive sampling. The entire sample is collected and placed in a storage box. During control sampling, a 50cm×50cm×50cm sediment sample is collected in the control sub-area. Using the stratified sampling method, sediments from the surface, middle, and deep layers are collected respectively. Aquatic biological samples are collected after washing through a 0.5mm sieve.

[0035] S4, Sample Processing and Analysis: All collected samples are brought back to the laboratory. For plant floating bed samples, the aboveground part and the root part are carefully separated. The dry weight and wet weight are measured using a high-precision balance. At the same time, the chemical composition of the plant tissue is analyzed to detect the nutrient content and heavy metal content indicators. For other aquatic biological samples, they are first classified and screened to remove impurities. Then, species identification is carried out using a combination of morphological identification and molecular biological identification. For identified organisms, their individual size, weight and biological parameters are measured using precision measuring instruments.

[0036] S5, Data processing and evaluation index calculation: Establish a special database to input and manage the collected and analyzed data, and calculate various evaluation indicators, including species richness S, number of organisms N, and biomass density D. b , Biodiversity Index Shannon-Wiener Index H, biological species richness is obtained by statistically identifying the number of species, the number of organisms is the sum of the number of individuals of each species, and the biological density is calculated based on the area of ​​the sampling area and the number of organisms. Shannon-Wiener Index where p i is the proportion of the number 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 was evaluated.

[0037] Compared with existing technologies, the three-dimensional device for restoring estuary fishery habitats and the survey and assessment method have the following beneficial effects:

[0038] 1. This invention provides a diverse habitat for different types of aquatic organisms by constructing a three-dimensional restoration device including a plant floating bed area, a pipe reef area and a gabion cage area. The plant floating bed area can not only purify the water, but also provide a resting place for birds. At the same time, its root system provides an attachment matrix for fish eggs and fry. The pipe reef area provides a hiding and shelter place for fish and other aquatic organisms. Attached organisms such as oysters and barnacles can grow on the pipe wall. The gabion cage area provides a suitable habitat for shrimps, crabs and various benthic organisms. This three-dimensional habitat restoration device helps to improve the ecological diversity of estuarine fishery habitats, provide better habitat conditions for various aquatic organisms, and thus maintain ecological balance.

[0039] 2. This invention can comprehensively and accurately evaluate the restoration effect of the restoration device on estuarine fishery habitats through scientific and reasonable sampling time determination, sampling area division, sampling methods, and sample processing and analysis steps. By comparing the biological species richness, biological quantity, biological density and biodiversity index indicators in the restoration area and the control area, the effect of the restoration device can be quantitatively evaluated. At the same time, this 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 will help promote the scientific and standardized process of estuarine fishery habitat restoration work.

[0040] Other advantages, objects and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art based on an examination of the following or may be learned from the practice of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0042] Figure 1 Schematic diagram of the three-dimensional device for fishery habitat restoration;

[0043] Figure 2 Schematic diagram of pipeline reef;

[0044] Figure 3 Schematic diagram of gabion box;

[0045] Figure 4 Schematic diagram of plant floating bed;

[0046] Figure 5 A flowchart of the survey and assessment method for estuarine fishery habitat restoration;

[0047] In the figure: 1. Plant floating bed; 2. Pipe reef; 201. Stainless steel frame; 202. PVC pipe; 203. First nylon rope; 204. Hole in the PVC pipe; 3. Gabion box; 301. Stainless steel frame; 302. Wire cage; 303. Stone; 4. Anchor; 5. Stainless steel frame structure; 6. Second nylon rope; 7. Plant floating 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 DESCRIPTION

[0048] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0049] Example 1

[0050] This example describes a small estuary where fishery resources are gradually decreasing due to water pollution and habitat destruction. The intertidal zone in the estuary has slow currents and a primarily muddy bottom. The surrounding area is also subject to certain human activities, such as small-scale industrial emissions and agricultural non-point source pollution.

[0051] Based on the estuary water quality and biological needs, we selected reed and calamus plant roots to form floating bed plant modules. We measured the average volume of a single plant root and the number of plant roots in the module, calculated the total volume of the plant roots, and then calculated the total volume based on the module size. The plant root filling ratio was determined to be 60% according to the formula: Where P is the filling ratio of plant roots, Vr is the total volume of plant roots, V m The foam float adopts a partitioned structure to adjust the air pressure in the air chamber to balance the buoyancy and 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 pipe reef material. After studying the body size distribution of estuarine fish, it was decided to use three PVC pipes with diameters of 10cm, 15cm, and 20cm, with 6, 5, and 4 pipes respectively. At a height of 0.5m, the PVC pipes were fixed on the frame at a 45° angle to the water flow direction, so that they can generate turbulence to increase oxygen and facilitate the entry and exit of organisms. The number of holes on a single PVC pipe is set according to the pipe diameter specifications and ecological function requirements, and the hole distribution density is reasonably distributed after calculation.

[0053] The gabion cage adopts a double-twisted hexagonal woven structure of wire mesh. The wire diameter is 3mm, the vertical distance between adjacent wires is 5mm, and the twisting angle is determined by the formula α=arctan(3 / 5). The mesh size is initially set to 5cm×5cm and adjusted according to the development of the biological community. Each cage is filled with three specifications of stones, namely 5cm-10cm, 10cm-15cm, and 15cm-20cm. Each specification is filled with 4 cages, a total of 16 cages. After calculating the filling ratio of stones of different specifications, the formula is: where R i is the filling ratio of the i-th specification stone, N i is the number of stones of the i-th specification, N t is the total number of stones in the gabion box, which are placed in the lower square of the frame using a layered random filling algorithm.

[0054] The bottom of the stainless steel frame is welded with steel plates, and steel pipes are welded at heights of 0.25m and 0.75m with 50cm intervals horizontally and vertically 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 rope around it. The length of the nylon rope is monitored in real time according to the changes in tidal water level and the impact force of the water flow, and can be adjusted within the range of 3m-5m.

[0055] One month after the restoration device is installed, the first survey and assessment will be conducted in the spring when the water temperature rises. Subsequent sampling will be carried out during specific seasonal periods, including the peak biological growth period in summer, after the biological reproduction period in autumn, and before the biological dormancy period in winter.

[0056] The area where the restoration device is located is divided into four sub-areas using geographic information system technology. Each sub-area includes a plant floating bed area, a pipeline reef area and a part of the gabion box area. At the same time, a control sub-area of ​​the same area and shape is divided on the nearby mudflats.

[0057] 30% of the gabions in each sub-area were randomly selected in layers, and samples were collected from the upper, middle and lower layers of the gabions with different specifications. Benthic animals and attached organisms were collected using special sampling tools.

[0058] Three groups of PVC pipes were randomly selected from the pipeline reef in each sub-area, and biological samples were collected from the inlet, middle and outlet, and the organisms in the pipes were gently flushed.

[0059] The height, density, and coverage area growth indicators of the plants on the floating bed were measured, and 10 floating bed plant modules were evenly spaced for destructive sampling, and the samples were collected and stored in a sorting box; 50cm×50cm×50cm sediment samples were collected from the control area, and after stratified sampling, the aquatic biological samples were collected by washing through a 0.5mm sieve.

[0060] The samples are brought back to the laboratory, and the above-ground and root parts of the plant floating bed samples are separated to measure the dry weight, wet weight and analyze the chemical composition. After other aquatic biological samples are classified and screened and impurities removed, the species are identified using morphology and molecular biology, and the individual size and weight biological parameters are measured using precision instruments.

[0061] Establish a database to input data, calculate species richness, quantity, density, and Shannon-Wiener index evaluation indicators, where p i The proportion of the number of individuals of the i-th species to the total number of individuals is used to evaluate the restoration effect by comparing the differences between the restoration area and the control area.

[0062] Example 2

[0063] This embodiment describes a situation in which, due to the construction of various water conservancy projects such as beach reclamation in a certain estuary area, there is a serious loss of aquatic habitats in the intertidal zone, a significant decrease in the number of fish and benthic organisms, and an imbalance in the aquatic ecosystem.

[0064] Reeds with well-developed root systems are selected to fill the floating bed plant modules. The floating bed plant modules are placed in the upper square of the stainless steel frame and fixed with angle irons, screws and nylon ropes. Foam floats around them adjust the buoyancy to ensure that they float smoothly with the tide.

[0065] After material testing, PVC pipes were selected. The pipe diameter specifications were determined based on the size distribution of fish in the estuary (mostly small and medium-sized fish). Small and medium-sized pipes were mainly used. The PVC pipes were fixed to the upper grid of the frame at a specific angle (45° to the direction of water flow) and height (adjusted according to sunlight). The hole distribution density was calculated and set according to the ecological function requirements. The formula is: Where D is the hole distribution density, n is the number of holes 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 adopts a double-twisted hexagonal woven structure. The mesh size is initially large and is subsequently adjusted according to the growth of benthic organisms. After the stones are treated with a bioaffinity coating, they are filled with stones of different specifications according to a layered random filling algorithm. The formula is: where R i is the filling ratio of the i-th specification stone, N i is the number of stones of the i-th specification, N t It is the total number of stones in the gabion cages, which are placed in the bottom square of the frame to provide a habitat for shrimps, crabs and benthic organisms.

[0067] The stainless steel frame adopts a staggered welding process, with steel pipes welded at intervals horizontally and vertically to form a grid, a steel plate base welded at the bottom, and adjustable nylon ropes connected to flat anchors suitable for the bottom (mud) around it. The length of the nylon rope is adjusted according to the tidal water level and water flow impact force monitoring data 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 seasonal characteristics, and the restoration device and nearby mudflats were divided into multiple sub-areas using a geographic information system to ensure comparability between the restoration area and the control area.

[0069] Samples from plant floating beds, pipeline reefs, gabion cages and control areas were collected according to their respective sampling methods and brought back to the laboratory for processing and analysis, including plant weight, component analysis, biological classification, identification and parameter measurement.

[0070] After data processing and evaluation index calculation, the richness, number, density and diversity index of biological species in the restoration area were significantly higher than those in the control area, and the number of fish and benthic organisms gradually increased, indicating that the device can provide suitable habitats for various swimming animals and benthic animals in the estuary, and has a significant effect on the restoration of the estuary fishery habitat.

[0071] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modifications to the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any brief modifications, changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still belong to the technical solution of the present invention.

Claims

1. A three-dimensional device for restoring estuary fishery habitats, characterized in that: The device includes a plant floating bed area, a pipeline reef area, a gabion box area and a stainless steel frame structure; The plant floating bed area includes: foam floats, angle irons, screw holes on the angle irons for fixing the floating bed, plant roots, and polyethylene mesh; The pipeline reef area includes: a stainless steel frame, a PVC pipe, a first nylon rope, and a hole opened on the PVC pipe; The gabion box area includes: stainless steel frame, wire mesh cage, and stones; Plant floating bed area: Located on the upper part of the stainless steel frame device, it consists of foam floats, stainless steel pipe frames and floating bed plant modules. The upper part of the stainless steel frame is welded into 9 squares by angle irons. A floating bed plant module is placed in each square. The module and the frame are fixed with screws through the holes on the angle irons. The floating bed plant module consists of two layers of polyethylene mesh and plant roots filled in the middle. It is clamped and fastened with plastic ties. The entire floating bed frame is nested in the stainless steel frame and located at the top of the frame. It is connected to the frame with nylon ropes. The foam floats around it enable the floating bed to float up and down with the tide without leaving the frame. Plant growth can purify the water. The floating bed surface provides a resting place for birds, and the roots provide an attachment matrix for fish eggs and larvae. The filling ratio of plant roots in the floating bed plant module is determined by the following formula: ,in is the plant root filling ratio, is the total volume of the plant root system, is the total volume of the floating bed plant module. The total volume of the plant root system is obtained by measuring the product of the average volume of a single plant root and the number of plant roots in the module. The total volume of the floating bed plant module is calculated based on the size of the module. Pipeline reef area: Located in the middle of the stainless steel frame device and above the gabion cage, five PVC pipes of different diameters are placed in the 16 squares on the upper part of the frame, one group in each square, and fixed to the frame with nylon rope. The pipeline reef area provides a hiding place and shelter for fish and aquatic organisms. Attached organisms can grow on the pipe wall. The density of the hole distribution on the PVC pipe is calculated according to the following formula: ,in is the hole distribution density, is the number of holes on a single PVC pipe, is the radius of the PVC pipe, is the length of the PVC pipe. The number of holes on a single PVC pipe is set according to the ecological function requirements of PVC pipes of different diameters. Gabion box area: The gabion box area is set at the bottom of the stainless steel frame device. The independent cage net is made of lead wire cage. The weaving structure and mesh size are designed as follows: The wire cage adopts a double-twisted hexagonal braided structure, which has high stability and strength. During the braiding process, the twisting angle of the wire is accurately calculated. Determined according to the following formula: ,in is the lead wire diameter, The vertical distance between adjacent lead wires is optimized by adjusting the lead wire diameter and vertical distance, and the twisting angle is optimized. The mesh size is designed according to the size of the target benthic organisms. A dynamic adaptive mesh size algorithm is used. First, the body size data of common benthic organisms in the estuary are statistically analyzed to obtain the distribution range of the organism size. According to the distribution of organism size, the mesh size is divided into multiple levels, and each level corresponds to a certain range of organism 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 to ensure that the mesh size always adapts to the growth and Habitat needs, each cage net is filled with stones of different sizes, and 4 cage nets are filled for each size, for a total of 16 cage nets, which are randomly placed in the 16 small squares at the bottom of the frame device. The frame is surrounded by detachable cross bars. The cage provides a suitable habitat for shrimps, crabs and various benthic organisms. The filling layout of stones of different sizes 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 size of stone, a small unit is randomly selected for filling. The filling ratio of stones of different sizes in the gabion cage is calculated according to the following formula: ,in For the Filling ratio of various specifications of stones, For the The number of stones of different specifications, The total number of stones in the gabion box is determined by the volume of the box, the size of the stones and the habitat requirements of the organisms. The surface treatment method of the stones is: The stone surface is treated with a bio-affinity coating. The coating material is a mixture of natural biological materials and organic binders. Natural biological materials include shell powder and coral powder, which are rich in calcium and magnesium. The coating preparation process includes mixing the natural biological materials and organic binders in a certain proportion. The coating is evenly covered on the stone surface by spraying or immersion. The coating thickness is calculated and determined by the following formula: ,in is the coating thickness, is the mass of coating per unit area, is the density of the coating material, is the surface area of ​​the stone; Stainless steel frame structure: A stainless steel welded frame is used as a fixing device, and a steel plate is welded at the bottom as a base to prevent it from sinking into the sediment. Steel pipes are welded horizontally and vertically at heights of 0.25m and 0.75m with intervals of 50cm to form 16 small squares of 50cm×50cm. The entire frame is connected with anchors with nylon ropes on all sides to fix the device in the intertidal zone of the estuary to prevent it from being knocked down by extreme weather such as typhoons. The welding process of the frame adopts a staggered welding method. The horizontal and vertical steel pipes are first spot-welded at each intersection, and then starting from a corner of the frame, continuous welding is performed in a specific order. After each welding distance, an intersection is skipped and welding is continued. The determination of this welding sequence is based on the force analysis of the frame under the impact of water flow and wind and waves. It has been verified through simulation experiments that it can effectively improve the impact resistance of the frame.

2. The three-dimensional device for restoring estuary fishery habitat according to claim 1, characterized in that: 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: An ecological function analysis was conducted on the roots of common aquatic plants in the intertidal zone of the estuary, including their ability to absorb nitrogen and phosphorus nutrients in the water body and the stability of attachment provided for fish eggs and larvae. An evaluation model for the ecological function of plant roots was established. The evaluation indicators included root surface area, root hair density, and secretion composition. Through field sampling and laboratory analysis of the roots of various plants, data for various evaluation indicators were obtained. The hierarchical analysis method was used to determine the weight of each evaluation indicator. The comprehensive ecological function value of each plant root was calculated according to the evaluation model, and plant root combinations with higher comprehensive ecological function values ​​were selected for the floating bed plant module. The combination method was matched according to the characteristics of different plant root systems.

3. The three-dimensional device for restoring estuary fishery habitat according to claim 1, characterized in that: The material selection and pipe diameter specification determination method of the PVC pipe are as follows: Pipes made of different materials were tested for corrosion resistance, strength and biocompatibility. Pipe samples of different materials were placed in a simulated environment in the intertidal zone of the estuary. Changes in the physical properties of the pipes were regularly inspected, and the attachment and growth of organisms on the pipe surface were observed. After a long period of testing and comparison, it was found that PVC material performed relatively balanced in terms of corrosion resistance, strength and biocompatibility, and was suitable as a material for pipeline reefs. For the determination of pipe diameter specifications, the body size distribution of estuarine fish and other aquatic organisms was studied, and the cluster analysis method was used to classify the body sizes of organisms into different categories. According to the number ratio of each category of organisms and the activity space requirements, the number of PVC pipes with different diameters was determined.

4. The three-dimensional device for restoring estuary fishery habitat according to claim 1, characterized in that: The connection method between the device frame and the anchor is: An adjustable-length nylon rope is used to connect the frame and the anchor. One end of the nylon rope is fixed to a specific position on the frame through a special buckle structure. The buckle structure can ensure that the nylon rope will not fall off when subjected to tension and is easy to install and disassemble. 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 muddy bottoms, a flat anchor is used, which has a larger area and can provide greater mechanical strength. For sandy bottoms, a claw anchor is used, whose claws can penetrate into the sand layer to enhance the anchoring effect. The length of the nylon rope can be adjusted in the range of 3m-5m. The adjustment mechanism is based on 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, and the length of the nylon rope is automatically adjusted according to the monitoring data to keep the device stable under different water levels and water flow conditions.

5. The three-dimensional device for restoring estuary fishery habitat according to claim 1, characterized in that: The buoyancy adjustment method of the foam float of the plant floating bed is as follows: The interior of the foam float adopts a partitioned structure, which is divided into multiple independent air chambers. Each air chamber is equipped with a valve that can adjust the air pressure. The valve can control the inflow and outflow of the air chamber, thereby adjusting the buoyancy of the foam float. The buoyancy adjustment is based on the balance calculation of the overall weight of the device and the buoyancy of the tide. First, the total weight of the plant floating bed, pipeline reef, gabion cage and attached organisms is measured. According to the density of the tide and the volume of the device submerged in tidal water , calculate the required buoyancy , where g is the acceleration due to gravity. By adjusting the air pressure in the foam float chamber, 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 up and down smoothly with the tide and will not fall off the frame due to excessive buoyancy under extreme weather conditions.

6. The three-dimensional device for restoring estuary fishery habitat according to claim 1, characterized in that: The fixed angle and height of the PVC pipe in the pipeline reef on the frame are set as follows: The fixing angle of the PVC pipe on the frame is optimized according to the direction of the estuary water flow and the lighting conditions. Through long-term monitoring of the estuary water flow direction, the main flow direction and flow rate change pattern of the water flow are obtained, and the PVC pipe is fixed on the frame so that it forms a certain angle θ with the water flow direction. The value range of θ is 30°-60°. This angle setting can cause turbulence when the water flows through the PVC pipe, increase the oxygen content in the water, and facilitate the entry and exit of organisms into the pipe warehouse. As for the lighting conditions, the height of the PVC pipe is adjusted according to the changes in sunshine time and solar altitude angle in the estuary area, so that the PVC pipe can obtain appropriate light 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 can be precisely adjusted according to actual needs.

7. The method for investigation and assessment of estuarine fishery habitat restoration is characterized by: The method is a three-dimensional device for restoring estuarine fishery habitats based on any one of claims 1 to 6, and the specific steps of the method are: S1. Determination of sampling time: The first survey and assessment will begin one month after the restoration device is installed. The intervals for subsequent assessments will be determined based on the seasonal changes in the estuarine ecosystem and the biological growth cycle. Surveys and sampling will be arranged in spring, summer, autumn, and winter. This sampling schedule can fully reflect the effects of the restoration 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 plant floating bed area, a pipeline reef area, and a portion of a gabion cage area. A control sub-area of ​​the same size and shape is also established on the nearby mudflats. Geographic information system technology is used to accurately divide the sub-areas based on the topographic and geomorphological characteristics of the device and mudflats to ensure that each sub-area is representative and that the environmental conditions of the sub-areas in the restoration and control areas are comparable. S3, sampling method: Gabion cage sampling: From the gabion cages in each sub-area, a certain proportion of the cages were selected for sampling according to the random stratified sampling method. For cages with stones of different specifications, samples were collected from the upper, middle and lower layers. All aquatic organisms, including benthic animals and barnacles and oysters attached to the stones, were collected into sample bottles. The sampling process used sampling tools that could penetrate into different locations inside the cages to avoid damage to the organisms and ensure that the collected samples were comprehensive. Pipeline reef sampling: Randomly select several groups of PVC pipes from the pipeline reefs in each sub-area for sampling. For each group of PVC pipes, collect biological samples from the inlet, middle, and outlet. Collect all organisms in the PVC pipes into sample bottles. During sampling, use a gentle flushing method to flush the organisms out of the pipes while avoiding washing away small organisms or damaging biological tissues. Plant floating bed sampling: In each sub-area of ​​the plant floating bed, first measure the height, density, and coverage area growth indicators of the above-ground plants using non-destructive measurement methods. Then, select a certain number of modules from the floating bed plant modules according to the equidistant sampling method for destructive sampling. The entire sample is collected and placed in a storage box. During control sampling, a 50cm×50cm×50cm sediment sample is collected in the control sub-area. Using the stratified sampling method, sediments from the surface, middle, and deep layers are collected respectively. Aquatic biological samples are collected after washing through a 0.5mm sieve. S4, Sample Processing and Analysis: All collected samples are brought back to the laboratory. For plant floating bed samples, the aboveground part and the root part are carefully separated. The dry weight and wet weight are measured using a high-precision balance. At the same time, the chemical composition of the plant tissue is analyzed to detect the nutrient content and heavy metal content indicators. For other aquatic biological samples, they are first classified and screened to remove impurities. Then, species identification is carried out using a combination of morphological identification and molecular biological identification. For identified organisms, their individual size, weight and biological parameters are measured using precision measuring instruments. S5, Data processing and evaluation index calculation: Establish a special database to enter and manage the collected and analyzed data, and calculate various evaluation indicators, including species richness , number of organisms , biomass density , Biodiversity Index Shannon-Wiener Index The species richness is calculated by counting the number of species identified, the number of organisms is the sum of the number of individuals of each species, and the biodensity is calculated based on the area of ​​the sampling area and the number of organisms. The Shannon-Wiener index ,in For the The proportion of the number of individuals of each species to the total number of individuals was measured. 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 was evaluated.

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