A device and method for studying the driving mechanism of fish approach-avoidance behavior in special water bodies with water temperature stratification and TDG saturation stratification

Abstract

The present invention provides an apparatus and method for studying the driving mechanism of fish avoidance behavior in special water bodies with water temperature stratification and TDG saturation stratification. The apparatus includes a TDG supersaturated water body generation device, an experimental water tank, and a fish avoidance behavior monitoring system. The experimental water tank includes a diffusion section located at the water inlet of the water tank, a fish avoidance behavior experimental area located in the middle of the straight section of the water tank, a hydrodynamic and water quality monitoring device located upstream of the fish avoidance behavior experimental area, longitudinal fish restraining nets located upstream and downstream of the experimental area, a vertical fish restraining net located in the experimental area, an adjustable water baffle and tailwater tank at the end of the straight section, and an outlet pipe located at the bottom of the tailwater tank. The present invention can create different water temperature stratification and TDG saturation stratification structures, synchronously measure the activity of experimental fish, as well as key hydrodynamic and water quality parameters, analyze the response mechanism of fish avoidance behavior to supersaturated TDG, and provide scientific support for river ecological protection.

Description

Technical Field

[0001] The present invention relates to the field of water environment and water ecological protection, and in particular to a device and method for studying the driving mechanism of fish approach-avoidance behavior in special water bodies with water temperature stratification and TDG saturation stratification. Background Art

[0002] Dam discharge carries air into the water, where large amounts of gas dissolve under the pressure of the water. This causes the water in the immediate area below the dam to become supersaturated with total dissolved gas (TDG). Cascade river development increases water depth and reduces flow velocity, slowing TDG dissipation and leading to prolonged transport within deep reservoirs. This can lead to fish mortality from gas bubble disease caused by the release of dissolved gas from tissues and fluids. According to Henry's law and the pathogenesis of gas bubble disease, the TDG saturation actually perceived by fish is related to the depth and temperature of the water in which they are located. Increased water depth increases the pressure on the total dissolved gas, while lower water temperature reduces the kinetic energy of water molecules, making it more difficult for TDG to precipitate from the water, resulting in a lower perceived TDG saturation by fish.

[0003] Previous studies have shown that some fish are sensitive to high TDG saturation levels and can mitigate damage from oversaturated TDG by intermittently diving. This led to the concept of depth compensation for TDG saturation. In addition to water depth, water temperature is also a key factor influencing TDG saturation. On the one hand, water temperature determines the equilibrium concentration of TDG, which in turn affects TDG saturation. On the other hand, the water temperature of oversaturated TDG water and the temperature stratification of the river channel determine the vertical distribution of TDG oversaturation.

[0004] However, the current definition of TDG saturation cannot accurately describe the actual perception of TDG by fish in their environment. The research methods for the driving mechanism of fish's avoidance behavior towards water bodies with high TDG saturation under water temperature stratification conditions are still imperfect, and it is impossible to achieve quantitative analysis of fish's avoidance behavior. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the background technology and provide a device and method for studying the driving mechanism of the approach and avoidance behavior of fish in special water bodies with water temperature stratification and TDG saturation stratification. The TDG saturation under depth compensation and temperature compensation is used to describe the actual perception of fish, and the precise adjustment of the water temperature stratification structure and TDG saturation stratification structure in the experimental tank is achieved, providing a quantification method for the approach and avoidance behavior of fish.

[0006] To achieve the above-mentioned object, the present invention provides a device for studying the driving mechanism of fish avoidance behavior in special water bodies with water temperature stratification and TDG saturation stratification, comprising a TDG supersaturated water body generation device, an experimental water tank, and a fish avoidance behavior monitoring system;

[0007] A device for studying the driving mechanism of fish avoidance behavior in special water bodies with water temperature stratification and TDG saturation stratification, including a TDG supersaturated water body generation device, an experimental water tank, and a fish avoidance behavior monitoring system;

[0008] The TDG supersaturated water body generating device includes several dissolution tanks, which are connected to the air compressor and the water tank by pipes. A variable frequency water pump and a liquid replenishing valve are installed in the pipe between the water tank and the dissolution tank. An air inlet valve is installed in the pipe between the air compressor and the dissolution tank. A thermometer and a pressure gauge are installed on the dissolution tank, and a temperature control device is installed inside the dissolution tank.

[0009] The experimental water tank includes a diffusion section located at the water inlet of the water tank, a rectifying grid located at the entrance of the straight section, an adjustable thermal insulation plate located upstream of the diffusion section and the straight section of the water tank, a fish avoidance behavior experimental area located in the middle of the straight section of the water tank, a water parameter monitoring device located upstream of the fish avoidance behavior experimental area, a sampling hole located on the side wall of the water tank upstream of the fish avoidance behavior experimental area, longitudinal fish limiting nets located upstream and downstream of the fish avoidance behavior experimental area, a vertical fish limiting net located in the fish avoidance behavior experimental area, an adjustable water baffle and a tailwater tank located at the end of the straight section, and a water outlet pipe located at the bottom of the tailwater tank;

[0010] The top, middle and bottom of the diffusion section of the experimental water tank are connected to different dissolution tanks by pipelines, and the pipelines are equipped with variable frequency water pumps, pipeline valves and electromagnetic flowmeters to adjust and monitor the flow of each pipeline into the experimental water tank in real time;

[0011] The fish avoidance behavior monitoring system includes a high-speed camera located outside the side wall of the fish avoidance behavior experimental area and a high-speed camera located at the top of the fish avoidance behavior experimental area. The fish's lateral swimming speed and tail-swinging frequency are analyzed using pictures taken by the high-speed camera at the top of the fish avoidance behavior experimental area, and the fish's longitudinal and vertical swimming speeds are analyzed using pictures taken by the high-speed camera outside the side wall of the fish avoidance behavior experimental area.

[0012] Furthermore, the adjustable insulation plate includes an insulation plate, a vertical slide rail fixed on the inner side walls on both sides of the upstream of the diffusion section and the straight section of the experimental water tank, a vertical slide seat that can slide vertically is connected to the vertical slide rail, and the insulation plate is fixed on the vertical slide seat.

[0013] Furthermore, by changing the vertical position of the insulation board, the flow of the variable frequency water pump and the position of the water baffle are adjusted synchronously, and the vertical distribution structure of the water temperature is adjusted while the water level remains unchanged.

[0014] Furthermore, fixed fish limiting nets are provided at the upstream and downstream boundaries of the fish avoidance experimental area, and adjustable fish limiting nets are provided vertically, which can confine fish within specific longitudinal and vertical ranges.

[0015] Furthermore, the adjustable fish limiting net includes a fish limiting net, vertical slide rails fixed on the side walls on both sides of the fish avoidance behavior experimental area, the vertical slide rails are connected to a vertical slide seat that can slide vertically, and the fish limiting net is fixed on the vertical slide seat.

[0016] Furthermore, the vertical movement range of the experimental fish was restricted by changing the vertical positions of the top and bottom fish limiting nets.

[0017] A method for studying the driving mechanism of fish approach-avoidance behavior in a special water body with water temperature stratification and TDG saturation stratification is carried out using the above-mentioned device, and the method comprises the following steps:

[0018] S1: Select the target fish species and quantity, and determine the water temperature suitable for the survival of the target fish;

[0019] S2: Open the valve of the dissolution tank, adjust the frequency of the variable frequency water pump and the position of the water baffle to fill the experimental tank to the target water level, and place the selected fish in the avoidance behavior experimental area;

[0020] S3: Control the water temperature in the dissolution tank within a water temperature range suitable for the survival of target fish to form a water temperature gradient;

[0021] S4: Observe whether there is a significant difference in the vertical distribution of fish populations in the experimental area under specific water temperature stratification conditions. If there is a significant difference, re-execute S3;

[0022] S5: Adjust the position of the insulation board, the frequency of each variable frequency water pump and the position of the water baffle to change the water temperature stratification structure;

[0023] S6: According to the water temperature in the dissolution tank and the average water depth of the specific water temperature area, the TDG saturation gradient under the compensation effect is set, the dissolution tank is pressurized, and the vertical position of the fish limiting net is adjusted to confine the fish to a specific vertical range;

[0024] S7: Adjust the position of the fish limiting net to remove the restriction on the vertical range of fish movement, and monitor and analyze key data such as fish movement, water dynamics, and water quality;

[0025] S8: Post-process key parameters of fish activity using image analysis software;

[0026] S9: According to the experimental conditions, whether to change the water temperature stratification structure in the experimental water tank and re-execute S5~S8;

[0027] S10: According to the experimental conditions, whether to change the TDG saturation layer structure in the experimental tank and re-execute S6~S9;

[0028] S11: Comprehensively analyze the experimental results under different working conditions to study the driving mechanism of fish approach-avoidance behavior in special water bodies with temperature and saturation stratification.

[0029] Furthermore, the TDG saturation under the compensation effect described in step S6 is calculated according to the following steps. First, the oxygen saturation concentration and the nitrogen saturation concentration are calculated according to the atmospheric pressure, air temperature, humidity, and water temperature in the experimental environment:

[0030] Oxygen saturation concentration:

[0031]

[0032] In the formula is the oxygen saturation concentration, mg / L; is the local atmospheric pressure, atm; T is the water temperature, °C;

[0033] Nitrogen saturation concentration:

[0034]

[0035]

[0036]

[0037]

[0038] In the formula is the nitrogen partial pressure, atm; is the Henry constant, atm -1 ; RH is relative humidity; is the water vapor pressure at relative humidity of 100%, mmHg; T air is the air temperature, ℃; Td is the dew point temperature, ℃; T is the water temperature, ℃;

[0039] Then, the temperature-compensated TDG saturation is calculated based on the real-time oxygen and nitrogen concentrations read at each water quality monitoring point in the water tank:

[0040] TDG saturation under temperature compensation:

[0041]

[0042] Where TDG t is the total dissolved gas saturation under temperature compensation, %; is the oxygen concentration in water measured by membrane inlet mass spectrometer (MIMS), mg / L; is the oxygen saturation concentration in the water tank experimental environment, mg / L; is the nitrogen concentration in water measured by membrane inlet mass spectrometer (MIMS), mg / L; is the saturated nitrogen concentration in the water tank experimental environment, mg / L;

[0043] Finally, the water depth at the water quality monitoring point in the water tank is measured, and the depth compensation effect is coupled with the temperature compensation to calculate the TDG saturation under the compensation effect:

[0044] TDG saturation under compensation effect:

[0045]

[0046] Where TDG is the total dissolved gas saturation under compensation effect, %; is the local atmospheric pressure, KPa; is the density of water, kg / m³; g is the acceleration due to gravity, m 2 / s; h is the water depth, m.

[0047] Furthermore, the key parameters of fish activity described in step S8 include: fish swimming speed, fish tail wagging frequency, and distribution of fish number along the depth direction at characteristic time points.

[0048] Furthermore, the swimming speed of fish is calculated using the following formula:

[0049]

[0050]

[0051]

[0052]

[0053] Where V is the swimming speed of fish, m / s; 、 、 is the horizontal, longitudinal and vertical swimming speed of the fish; N is the shooting frequency of the high-speed camera, 1 / s; 、 、 is the change in the horizontal, vertical, and vertical positions of the fish between the two frames, m;

[0054] The fish tail-wagging frequency is calculated using the following formula:

[0055]

[0056] Where P is the fish tail-swinging frequency, Hz; N is the shooting frequency of the high-speed camera, Hz; and n is the number of consecutive photo frames required to extract the fish's tail-swinging process, fps.

[0057] The present invention has the following beneficial effects:

[0058] 1. This invention uses temperature- and depth-compensated TDG saturation to accurately describe the TDG saturation actually perceived by fish in a specific environment. It also precisely quantifies fish avoidance behavior through parameters such as fish motion trajectory, cumulative number of experimental fish as a function of water depth, fish swimming speed, and fish tail-wagging frequency. This provides a scientific approach for studying the driving mechanism of fish avoidance behavior in response to oversaturated TDG.

[0059] 2. The present invention can accurately adjust and monitor the water temperature and TDG saturation vertical distribution structure in the experimental tank through the gas supersaturated water body generation device and the vertical movement device, and accurately control the longitudinal and vertical movement range of fish, meeting the basic needs of testing the driving mechanism of fish approach and avoidance behavior in special water bodies with water temperature stratification and TDG saturation stratification. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 This is a schematic diagram of the structure of the device used in the present invention to study the driving mechanism of the approach-avoidance behavior of fish in special water bodies with water temperature stratification and TDG saturation stratification;

[0061] Figure 2 Schematic diagram of the structure of the experimental water tank of the present invention, wherein (a) is a top view and (b) is a side view;

[0062] Figure 3 This is a schematic structural diagram of a TDG supersaturated water generating device according to the present invention;

[0063] Figure 4 It is a structural schematic diagram of the vertical moving device of the present invention;

[0064] Figure 5 This is a flow chart of the method for studying the driving mechanism of fish approach-avoidance behavior in special water bodies with water temperature stratification and TDG saturation stratification according to the present invention;

[0065] Figure 6 This is a diagram of the experimental working conditions of the present invention.

[0066] In the figure: 1-water inlet pipe, 2-frequency conversion water pump, 3-pipeline valve, 4-electromagnetic flowmeter, 5-experimental water tank diffusion section, 6-rectifier grid, 7-experimental water tank straight section, 8-adjustable thermal insulation board, 9-vertical slide rail, 10-vertical slide seat, 11-motor, 12-rope, 13-sampling hole, 14-MIMS membrane injection mass spectrometer, 15-water temperature probe, 16-ADV flowmeter, 17-longitudinal fish limiting net, 18-vertical fish limiting net, 19-experimental water tank side high-speed camera, 20-experimental water tank top high-speed camera, 21-adjustable water baffle, 22-tail water tank, 23-water outlet pipe, 24-water tank, 25-thermometer, 26-pressure gauge, 27-inlet valve, 28-liquid replenishing valve, 29-air compressor, 30-dissolution tank, 31-water temperature regulating device. DETAILED DESCRIPTION

[0067] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, these embodiments do not limit the present invention and are merely examples to help those skilled in the art to more clearly understand the contents and advantages of the present invention.

[0068] like Figures 1 to 4 As shown, an embodiment of the present invention provides a device for studying the driving mechanism of fish avoidance behavior in special water bodies with water temperature stratification and TDG saturation stratification, including a TDG supersaturated water body generation device, an experimental water tank, and a fish avoidance behavior monitoring system.

[0069] The TDG supersaturated water body generating device includes several dissolution tanks 30, which are connected to the air compressor 29 and the water tank 24 by pipelines. A variable frequency water pump 2 and a liquid replenishing valve 28 are installed in the pipeline between the water tank 24 and the dissolution tank 30, an air intake valve 27 is installed in the pipeline between the air compressor 29 and the dissolution tank 30, a thermometer 25 and a pressure gauge 26 are installed on the dissolution tank 30, and a temperature control device 31 is installed inside the dissolution tank 30.

[0070] By adjusting the temperature control device 31 and the air compressor 29 in the dissolution tank 30 , a water body with a specific water temperature and TDG saturation can be formed in the dissolution tank 30 .

[0071] The experimental water tank includes: a diffusion section 5 located at the water inlet of the water tank, a rectifying grid 6 located at the entrance of the straight section 7, an adjustable thermal insulation plate 8 located upstream of the diffusion section 5 and the straight section 7 of the water tank, a fish avoidance behavior experimental area located in the middle of the straight section 7 of the water tank, a water parameter monitoring device located upstream of the fish avoidance behavior experimental area, a sampling hole 13 located on the side wall of the water tank upstream of the fish avoidance behavior experimental area, a longitudinal fish limiting net 17 located upstream and downstream of the fish avoidance behavior experimental area, a vertical fish limiting net 18 located in the fish avoidance behavior experimental area, an adjustable water baffle 21 and a tailwater tank 22 located at the end of the straight section 7, and a water outlet pipe 23 located at the bottom of the tailwater tank 22.

[0072] The top, middle and bottom of the diffusion section 5 of the experimental water tank are respectively connected to different dissolution tanks 30 by pipelines. The pipelines are equipped with a variable frequency water pump 2, a pipeline valve 3 and an electromagnetic flowmeter 4 to adjust and monitor the flow of each pipeline entering the experimental water tank in real time.

[0073] The adjustable thermal insulation board 8, water parameter monitoring device, and vertical fish retaining net 18 comprise a vertical movement mechanism comprising vertical rails 9 fixed to both sides of the diverging and straight sections of the flume. A vertical slide 10 is connected to the vertical rails 9, along with a motor 11 at the top of the rails and a rope 12 connecting the slide 10 and the motor 11. The adjustable thermal insulation board 8, water parameter monitoring device, and vertical fish retaining net 18 are fixed to the vertical slide 10, and the position of the slide 10 on the vertical rails 9 is controlled by the motor 11.

[0074] By changing the vertical position of adjustable thermal insulation plate 8 and adjusting the temperature control device 31, the opening of pipeline valve 3, and adjustable water baffle 21, the water temperature structure within the experimental water tank can be altered while maintaining the water level. Specifically, by adjusting temperature control device 31, the inflow water temperature within each vertical zone within the tank is determined. By changing the vertical position of adjustable thermal insulation plate 8 and correspondingly adjusting pipeline valve 3 to change the pipeline flow rate, the vertical distribution range and temperature gradient of the water temperature within the tank can be adjusted.

[0075] The water parameter monitoring device includes a water temperature probe 15 and an ADV flowmeter 16. The water temperature probe 15 and the ADV flowmeter 16 are both installed longitudinally on the vertical slide 10 to avoid the influence of the water parameter monitoring device on the flow state of the water. By adjusting the vertical position of the water parameter monitoring device, real-time monitoring of the vertical distribution structure of temperature and flow velocity can be achieved.

[0076] The sampling hole 13 is used to extract water samples at different depths in the experimental water tank. The water samples are analyzed by the MIMS membrane inlet mass spectrometer 14 to obtain the oxygen concentration and nitrogen concentration in the water body. Combined with the vertical water temperature distribution, real-time monitoring of the vertical distribution structure of TDG saturation under the compensation effect can be achieved.

[0077] Fixed longitudinal fish restraining nets 17 were installed at the upstream and downstream boundaries of the fish avoidance behavior experimental area to prevent fish from escaping the area. A vertical fish restraining net 18 with adjustable vertical position was installed within the experimental area to confine fish within a specific vertical range before the fish avoidance experiment began. The mesh size of the fish restraining net was determined by the size of the selected fish.

[0078] The fish avoidance behavior monitoring system includes a high-speed camera 19 located outside the side wall of the fish avoidance behavior experimental area and a high-speed camera 20 located on the top of the fish avoidance behavior experimental area.

[0079] like Figure 5 As shown, an embodiment of the present invention further provides a method for studying the driving mechanism of the approach-avoidance behavior of fish in a special water body with water temperature stratification and TDG saturation stratification, which is performed using the above-mentioned device, and the method includes the following steps:

[0080] S1: Select the target species and number of fish, and determine the water temperature suitable for the survival of the target fish. Specifically, collect the target species and number of fish from the wild or breeding grounds, count the biological characteristics of the fish (such as weight, body length, growth stage, etc.), screen the experimental fish to ensure that there are no significant differences in their biological characteristics. The experimental fish need to adapt indoors and fast before the experiment, and consult relevant literature to preliminarily determine the water temperature range suitable for the survival of the selected fish. Specifically, taking the schizothorax chinensis as an example, two-year-old schizothorax chinensis with a weight of 45±5g and a body length of 13±2cm were selected as experimental fish. They were placed in an indoor water tank for adaptation and fasted for 18h before the experiment. According to relevant data, the water temperature for the survival of schizothorax juveniles is 0.8~33.5℃, and the water temperature suitable for their growth and reproduction is 15~22℃;

[0081] S2: Open the pipe valve 3, adjust the frequency of each variable frequency water pump 2 and the position of the water baffle 21 to fill the experimental tank with water to the target water depth, and place the selected fish in the avoidance behavior experimental area after the water flow stabilizes. Specifically, to avoid excessive impact of depth compensation on TDG saturation, the target water depth of the experimental tank should not be too deep, and the target water depth is selected as 3m.

[0082] S3: Based on the water temperature range suitable for the survival of the selected fish species, the water temperature regulating devices 31 in each dissolution tank 30 are controlled to form a water temperature gradient within the experimental water tank. Specifically, based on the water temperature range suitable for the growth and reproduction of juvenile Schizothorax chinensis, a temperature gradient of 20-22°C is initially selected as the temperature gradient within the experimental water tank. The water temperatures in the three dissolution tanks 30 are controlled such that the inflow water temperatures entering the top, middle, and bottom of the experimental water tank are 22°C, 21°C, and 20°C, respectively.

[0083] S4: Under the specific water temperature stratification structure of the experimental tank, the high-speed camera 19 on the side of the experimental tank records the vertical distribution of the number of fish in the fish avoidance behavior experimental area, recording every 1 minute for 30 minutes. The open source image analysis software imageJ is used to analyze the images and draw a curve of the cumulative number of fish at each time point versus depth. If the curves at different time points show a uniform distribution pattern, repeat S3-S4 until no obvious pattern is found.

[0084] S5: Change the vertical position of the insulation plate 8 controlled by the motors 11 on both sides of the water tank, and simultaneously adjust the frequency of the variable frequency water pump 2 at different vertical positions upstream of the water tank to change the water temperature stratification structure. Specifically, when the vertical range of a specific water temperature is reduced, that is, when the spacing between adjacent insulation plates 8, between the insulation plate 8 and the free water surface, or between the insulation plate 8 and the bottom of the experimental water tank is reduced, the frequency of the variable frequency water pump 2 needs to be reduced to reduce the flow rate. Conversely, if the spacing increases, the frequency of the variable frequency water pump 2 needs to be increased to increase the flow rate. For specific flow rate adjustment, please refer to Figure 6 Experimental condition 2;

[0085] S6: According to the water temperature in the dissolution tank 30 and the average water depth of the specific water temperature area, the TDG saturation gradient under compensation is set, and the position of the vertical fish limiting net 18 is synchronously adjusted according to the depth range of the TDG supersaturated water body at a specific water temperature entering the experimental tank to limit the fish to a specific vertical range. Specifically, the specific parameters set for each working condition are as follows Figure 6 As shown, in order to comprehensively record the process of experimental fishes moving toward and avoiding TDG-supersaturated water, the vertical position of the experimental fishes needs to be limited to the position with higher TDG saturation.

[0086] The TDG saturation under the compensation effect is calculated according to the following steps: first, the oxygen saturation concentration and nitrogen saturation concentration are calculated according to the atmospheric pressure, air temperature, humidity, and water temperature in the experimental environment.

[0087] Oxygen saturation concentration:

[0088]

[0089] In the formula is the oxygen saturation concentration, mg / L; is the local atmospheric pressure, atm; T is the water temperature, ℃.

[0090] Nitrogen saturation concentration:

[0091]

[0092]

[0093]

[0094]

[0095] In the formula is the nitrogen partial pressure, atm; is Henry's constant, atm-1; RH is relative humidity; is the water vapor pressure at 100% relative humidity, mmHg; Tair is the air temperature, ℃; Td is the dew point temperature, ℃; T is the water temperature, ℃.

[0096] Then, the TDG saturation under temperature compensation is calculated based on the real-time oxygen and nitrogen concentrations read at each water quality monitoring point in the water tank.

[0097] TDG saturation under temperature compensation:

[0098]

[0099] Where TDGt is the total dissolved gas saturation under temperature compensation, %; is the oxygen concentration in water measured by membrane inlet mass spectrometer (MIMS), mg / L; is the oxygen saturation concentration in the water tank experimental environment, mg / L; is the nitrogen concentration in water measured by membrane inlet mass spectrometer (MIMS), mg / L; is the saturated nitrogen concentration in the water tank experimental environment, mg / L.

[0100] Finally, the water depth at the water quality monitoring point in the water tank is measured, and the depth compensation effect is coupled with the temperature compensation to calculate the TDG saturation under the compensation effect.

[0101] TDG saturation under compensation effect:

[0102]

[0103] Where TDG is the total dissolved gas saturation under compensation effect, %, is the local atmospheric pressure, atm, is the local atmospheric pressure, KPa; is the density of water, kg / m³; g is the acceleration due to gravity, m2 / s; h is the water depth, m.

[0104] S7: Adjust the position of the vertical fish limiting net 18 to remove the restriction on the vertical range of fish movement, use high-speed cameras 19 and 20 on the side and top of the tank to record the fish activities, and use water temperature probe 15, ADV flow meter 16, membrane injection mass spectrometer (MIMS) 14 to monitor and analyze key water dynamics and water quality data such as water temperature, flow rate, TDG saturation. Specifically, the shooting frequency of the high-speed camera on the side of the experimental water tank and the high-speed camera on the top of the experimental water tank is 300 Hz. Every 5 minutes, the vertical position of the water temperature probe 15 and the ADV flow meter 16 are adjusted to slide back and forth on the vertical guide rail 9 and record the vertical distribution of water temperature and flow rate. Every 10 minutes, water samples are extracted from the sampling holes 13 at each depth of the experimental water tank and the vertical distribution of TDG saturation is analyzed by the membrane inlet mass spectrometer (MIMS) 14. If the vertical distribution of water temperature, flow rate and TDG saturation does not meet the preset conditions, it is necessary to adjust the water temperature adjustment device 31 in the dissolution tank 30, the air inlet valve 27 and the frequency of the variable frequency water pump 2 in the water inlet pipe 1;

[0105] S8: After the experiment, the open source image analysis software imageJ was used to analyze the continuous multi-frame images taken by high-speed cameras 19 and 20 to extract data such as the movement trajectory of fish under different working conditions, the change of the cumulative number of experimental fish at different times with water depth, swimming speed, and tail-flicking frequency;

[0106] The swimming speed of fish can be calculated using the following formula:

[0107]

[0108]

[0109]

[0110]

[0111] Where V is the swimming speed of fish, m / s; 、 、 is the horizontal, longitudinal and vertical swimming speed of the fish; N is the shooting frequency of the high-speed camera, 1 / s; 、 、 is the change in the horizontal, vertical and vertical positions of the fish between the two frames of images, m.

[0112] The tail-wagging frequency of fish can be calculated using the following formula:

[0113]

[0114] Where P is the fish tail-swinging frequency, Hz; N is the shooting frequency of the high-speed camera, Hz; and n is the number of consecutive photo frames required to extract the fish's tail-swinging process, fps.

[0115] S9: According to the experimental working conditions, whether to change the water temperature stratification structure in the experimental water tank, re-execute S5 to S8, and carry out experiments under different working conditions;

[0116] S10: According to the experimental conditions, whether to change the TDG saturation layer structure in the experimental tank and re-execute S6~S9;

[0117] S11: Comprehensively analyze the experimental results under different working conditions to study the driving mechanism of fish approach-avoidance behavior in special water bodies with temperature and saturation stratification.

[0118] The present invention uses TDG saturation under temperature compensation and depth compensation to accurately describe the TDG saturation actually perceived by fish in a specific environment. The fish's approach and avoidance behavior is precisely quantified through parameters such as the fish's movement trajectory, the change in the cumulative number of experimental fish with water depth, the fish's swimming speed, and the fish's tail-wagging frequency, providing a scientific method for studying the driving mechanism of fish's approach and avoidance behavior to supersaturated TDG. The present invention can accurately adjust and monitor the water temperature and the vertical distribution structure of TDG saturation in the experimental water tank through a gas-supersaturated water body generation device and a vertical movement device, and accurately control the longitudinal and vertical movement range of the fish, meeting the basic needs of testing the driving mechanism of fish approach and avoidance behavior in special water bodies with water temperature stratification and TDG saturation stratification.

[0119] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by technicians in this technical field within the technical scope disclosed in the present invention should be covered by the scope of protection of the present invention.

Claims

1. A device for studying the driving mechanism of fish approach-avoidance behavior in water bodies characterized by temperature stratification and TDG saturation stratification, characterized by: It includes TDG supersaturated water generation device, experimental water tank, and fish avoidance behavior monitoring system; The TDG supersaturated water body generating device includes several dissolution tanks, which are connected to the air compressor and the water tank by pipes. A variable frequency water pump and a liquid replenishing valve are installed in the pipe between the water tank and the dissolution tank. An air inlet valve is installed in the pipe between the air compressor and the dissolution tank. A thermometer and a pressure gauge are installed on the dissolution tank, and a temperature control device is installed inside the dissolution tank. The experimental water tank includes a diffusion section located at the water inlet of the water tank, a rectifying grid located at the entrance of the straight section, an adjustable thermal insulation plate located upstream of the diffusion section and the straight section of the water tank, a fish avoidance behavior experimental area located in the middle of the straight section of the water tank, a water parameter monitoring device located upstream of the fish avoidance behavior experimental area, a sampling hole located on the side wall of the water tank upstream of the fish avoidance behavior experimental area, longitudinal fish limiting nets located upstream and downstream of the fish avoidance behavior experimental area, a vertical fish limiting net located in the fish avoidance behavior experimental area, an adjustable water baffle and a tailwater tank located at the end of the straight section, and a water outlet pipe located at the bottom of the tailwater tank; The top, middle and bottom of the diffusion section of the experimental water tank are respectively connected to different dissolution tanks by pipelines, and the pipelines are equipped with variable frequency water pumps, pipeline valves and electromagnetic flowmeters to adjust and monitor the flow of each pipeline into the experimental water tank in real time; The fish avoidance behavior monitoring system includes a high-speed camera located outside a side wall of the fish avoidance behavior experimental area and a high-speed camera located at the top of the fish avoidance behavior experimental area. The horizontal swimming speed and tail-wagging frequency of the fish are analyzed using pictures taken by the high-speed camera at the top of the fish avoidance behavior experimental area. The longitudinal and vertical swimming speeds of the fish are analyzed using pictures taken by the high-speed camera located outside a side wall of the fish avoidance behavior experimental area. The adjustable insulation plate includes an insulation plate, vertical slide rails fixed on the inner side walls of the diffusion section and the upstream straight section of the experimental water tank, the vertical slide rails are connected to a vertical slide seat that can slide vertically, and the insulation plate is fixed to the vertical slide seat; The longitudinal fish limiting nets set at the upstream and downstream boundaries of the fish avoidance behavior experimental area are fixed fish limiting nets, and the vertical fish limiting nets are adjustable fish limiting nets, which can limit fish to specific longitudinal and vertical ranges; The adjustable fish limiting net includes a fish limiting net and vertical slide rails fixed on the side walls on both sides of the fish avoidance behavior experimental area. The vertical slide rails are connected to a vertical slide seat that can slide vertically, and the fish limiting net is fixed on the vertical slide seat.

2. The device for studying the driving mechanism of fish approach-avoidance behavior in a special water body characterized by water temperature stratification and TDG saturation stratification according to claim 1, characterized in that: By changing the vertical position of the insulation board, synchronously adjusting the frequency conversion water pump flow and the position of the water baffle, the vertical distribution structure of the water temperature can be adjusted while keeping the water level unchanged.

3. The device for studying the driving mechanism of fish approach-avoidance behavior in a special water body characterized by water temperature stratification and TDG saturation stratification according to claim 1, characterized in that: The vertical movement range of the experimental fish was restricted by changing the vertical positions of the top and bottom fish limiting nets.

4. A method for studying the driving mechanism of fish approach-avoidance behavior in special water bodies with temperature stratification and TDG saturation stratification, characterized in that The method is carried out using the device according to any one of claims 1 to 3, and comprises the following steps: S1: Select the target fish species and quantity, and determine the water temperature suitable for the survival of the target fish; S2: Open the valve of the dissolution tank, adjust the frequency of the variable frequency water pump and the position of the water baffle to fill the experimental tank to the target water level, and place the selected fish in the fish avoidance behavior experimental area; S3: Control the water temperature in the dissolution tank within a water temperature range suitable for the survival of target fish to form a water temperature gradient; S4: Observe whether there is a significant difference in the vertical distribution of fish populations in the experimental area under specific water temperature stratification conditions. If there is a significant difference, re-execute S3; S5: Adjust the position of the insulation board, the frequency of each variable frequency water pump and the position of the water baffle to change the water temperature stratification structure; S6: According to the water temperature in the dissolution tank and the average water depth of the specific water temperature area, the TDG saturation gradient under the compensation effect is set, the dissolution tank is pressurized, and the vertical position of the vertical fish limiting net is adjusted to confine the fish to a specific vertical range; S7: Adjust the position of the vertical fish limiting net to remove the restriction on the vertical range of fish movement, and monitor and analyze fish movement, water dynamics, and water quality; S8: Post-process key parameters of fish activity using image analysis software; S9: According to the experimental conditions, whether to change the water temperature stratification structure in the experimental water tank and re-execute S5~S8; S10: According to the experimental conditions, whether to change the TDG saturation layer structure in the experimental tank and re-execute S6~S9; S11: Comprehensively analyze the experimental results under different working conditions to study the driving mechanism of fish approach-avoidance behavior in special water bodies with temperature stratification and saturation stratification.

5. The method for studying the driving mechanism of fish approach-avoidance behavior in a special water body characterized by water temperature stratification and TDG saturation stratification according to claim 4, characterized in that: The TDG saturation under the compensation effect described in step S6 is calculated according to the following steps. First, the oxygen saturation concentration and the nitrogen saturation concentration are calculated according to the atmospheric pressure, air temperature, humidity, and water temperature in the experimental environment: Oxygen saturation concentration: ； In the formula is the oxygen saturation concentration, mg / L; is the local atmospheric pressure, atm; T is the water temperature, °C; Nitrogen saturation concentration: ； ； ； ； In the formula is the nitrogen partial pressure, atm; is the Henry constant, atm -1 ; RH is relative humidity; is the water vapor pressure at relative humidity of 100%, mmHg; T air is the air temperature, ℃; T is the water temperature, ℃; Then, the temperature-compensated TDG saturation is calculated based on the real-time oxygen and nitrogen concentrations read at each water quality monitoring point in the water tank: TDG saturation under temperature compensation: ； Where TDG t is the total dissolved gas saturation under temperature compensation, %; is the oxygen concentration in water measured by membrane inlet mass spectrometer MIMS, mg / L; is the nitrogen concentration in water measured by membrane inlet mass spectrometer MIMS, mg / L; Finally, the water depth at the water quality monitoring point in the water tank is measured, and the depth compensation effect is coupled with the temperature compensation to calculate the TDG saturation under the compensation effect: TDG saturation under compensation effect: ； Where TDG is the total dissolved gas saturation under compensation effect, %; is the local atmospheric pressure, KPa; is the density of water, kg / m³; g is the acceleration due to gravity, m 2 / s; h is the water depth, m.

6. The method for studying the driving mechanism of fish approach-avoidance behavior in a special water body characterized by water temperature stratification and TDG saturation stratification according to claim 4, characterized in that: The key parameters of fish activity described in step S8 include: fish swimming speed, fish tail wagging frequency, and the distribution of fish number along the depth direction at characteristic time points.

7. A method for studying the driving mechanism of fish approach-avoidance behavior in a special water body characterized by water temperature stratification and TDG saturation stratification according to claim 6, characterized in that: The swimming speed of fish is calculated using the following formula: ； ； ； ； Where V is the swimming speed of fish, m / s; 、 、 is the horizontal, longitudinal and vertical swimming speed of the fish; N is the shooting frequency of the high-speed camera, 1 / s; 、 、 is the change in the horizontal, vertical, and vertical positions of the fish between the two frames, m; The tail-wagging frequency of fish is calculated using the following formula: ； Where P is the fish tail-swinging frequency, Hz; n is the number of consecutive photo frames required to extract the fish's tail-swinging process, fps.

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