Method for evaluating integrity of aquatic organisms in river and lake water system

Abstract

The invention relates to the technical field of river and lake ecological evaluation, in particular to a river and lake water system aquatic organism integrity evaluation method which comprises the following steps: collecting aquatic organisms; counting the number of functional group classes of the benthonic animals and the fishes; testing delta 15N and delta 13C of the collected aquatic organisms, making a scatter diagram, calculating a union of delta 15N and delta 13C distribution ranges of phytoplankton and zooplankton, and taking an overlapping area proportion of delta 15N and delta 13C distribution ranges of fishes as an overlapping degree; calculating the average nutrition level of the fish; and calculating and evaluating the food web structure of the aquatic organisms in the river and the lake and the integrity of the aquatic organisms in the water system according to the number of functional group classes, the overlapping degree and the average nutritional grade score of the fishes. According to the method, a certain water body is comprehensively evaluated, a clear evaluation standard is given, and the method has the advantages of being simple and easy to operate, avoiding randomness and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of river and lake ecological evaluation, and particularly relates to a method for evaluating the integrity of aquatic organisms in river and lake water systems. Background Art

[0002] With the development and progress of society, the healthy and sustainable development of water ecosystems has always been a topic of great concern. In order to carry out targeted water ecological protection and restoration work, it is necessary to evaluate the status of water ecosystems, analyze the existing problems and current situation of water ecosystems, and clarify the goals of water ecological protection and restoration.

[0003] The main indicators for evaluating the status of water ecosystems include three categories: water quality indicators, habitat indicators, and biological indicators. Among them, there are a series of technical standards and relatively mature research conclusions for water quality indicators and habitat indicators. However, due to the relatively late start of research on biological indicators, their development is not yet mature. At present, among the relevant standards for biological indicators issued, the focus is on evaluating biodiversity, and there is little systematic evaluation from the perspective of the food chain. This also makes the obtained evaluation results unable to reflect the feeding history and feeding process of organisms in water ecosystems. In addition, due to the difficulty of manual identification and the randomness of aquatic organism capture, it is difficult to evaluate the integrity of aquatic organisms.

[0004] In the prior art, there are methods for reflecting the structure of aquatic organisms through indicators such as omnivory index and water ecosystem stability. However, the methodology is extremely complex and requires basic data such as the full set of aquatic biomass of aquatic plants, planktonic animals and plants, benthic animals, and fish to build an Ecopath model. Due to the difficulty of obtaining biomass, combined with the randomness and human factors during the collection process of aquatic organisms, the accuracy of the evaluation is greatly reduced. For example, in existing standards such as the Beijing Local Standard DB11 / T 1722-2020 Technical Specification for Water Ecological Health Assessment and the SL / T 793-2020 Guidelines for River and Lake Health Assessment, the evaluation of species diversity and other evaluations during the evaluation process are highly random, and a large amount of complex manual identification is required, and it cannot reflect the transfer process of aquatic organisms along the food chain. There is a patent in the prior art that discloses a method for evaluating the stability of food webs using stable isotope technology. However, this patent mainly reflects the population competition relationship and stability through the trophic niche area and standard overlap area between different target groups and groups, and is used to evaluate the stability of a certain group of organisms; it cannot evaluate the overall status of the water body, nor does it consider the feeding relationships between all groups in the entire water ecosystem. There is also a patent in the prior art that discloses a method for constructing trophic niches and reflecting the interspecific food competition relationship of jellyfish based on their overlap. However, this patent focuses on the interspecific competition relationship of the target species of jellyfish to prevent and control harmful jellyfish; it does not care about all species in the target water body. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the deficiencies in the prior art that when evaluating the status of the water ecosystem, the evaluation methods of biological indicators are either cumbersome or inaccurate, and cannot reflect the transfer process of aquatic organisms along the food chain and the integrity of aquatic organisms. Thus, a method for evaluating the integrity of aquatic organisms in river and lake water systems is provided.

[0006] For this purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a method for evaluating the integrity of aquatic organisms in river and lake water systems, including the following steps: S1: Collect aquatic organisms; S2: Count the number of functional group taxa of benthic animals and fish; S3: Test the δ 15 N, δ 13 C of the collected aquatic organisms; S4: Use δ 13 C as the abscissa and δ 15 N as the ordinate, draw scatter plots according to the types of aquatic organisms, connect the scatter points to obtain the distribution ranges of different types of aquatic organisms, and calculate the degree of overlap; the degree of overlap is the union of the δ 15 N and δ 13 C distribution ranges of phytoplankton and zooplankton, and the proportion of the overlapping area of the δ 15 N and δ 13 C distribution ranges of fish; S5: Calculate the average trophic level of fish; S6: Evaluate the food web structure of aquatic organisms in river and lake water systems based on the number of functional group taxa, the degree of overlap, and the average trophic level of fish, evaluate the integrity of aquatic organisms in the water system, and the evaluation criteria are: a comprehensive score > 85 is rated as excellent, 85 ≥ comprehensive score > 70 is rated as good, 70 ≥ comprehensive score > 50 is rated as medium, 50 ≥ comprehensive score ≥ 30 is rated as poor, and comprehensive score < 30 is rated as inferior; the comprehensive score = 0.3 × the score of the number of functional group taxa + 0.4 × the score of the degree of overlap + 0.3 × the score of the average trophic level of fish.

[0008] In the method for evaluating the integrity of aquatic organisms in river and lake water systems provided by the present invention, benthic animals refer to large benthic invertebrates visible to the naked eye, such as annelids, mollusks, and arthropods, which inhabit the bottom of the water or attach to aquatic plants and stones.

[0009] Optionally, the evaluation criteria for the score of the number of functional group taxa are: when the number of functional group taxa > 6, it is counted as 100 points; when the number of functional group taxa is 6, it is counted as 70 points; when it is 4 or 5, it is counted as 50 points; when it is 3, it is counted as 30 points; when the number of functional group taxa < 3, it is counted as 0 points.

[0010] Optionally, the evaluation criteria for the score of the degree of overlap are: when the degree of overlap < 5%, it is counted as 100 points; when 5% ≤ degree of overlap < 30%, it is counted as 70 points; when 30% ≤ degree of overlap ≤ 50%, it is counted as 30 points; when the degree of overlap > 50%, it is counted as 30 points; when there are no fish, it is counted as 0 points.

[0011] Optionally, the evaluation criteria for the average trophic level score of fish are as follows: if the average trophic level of fish ≥ 3.5, it is counted as 100 points; if 3.5 > the average trophic level of fish ≥ 3, it is counted as 70 points; if 3 > the average trophic level of fish ≥ 2.5, it is counted as 50 points; if 2.5 > the average trophic level of fish ≥ 2, it is counted as 30 points; if there is no fish, it is counted as 0 points.

[0012] Preferably, in step S2, when counting the number of functional group taxa, fish are classified into carnivorous fish, omnivorous fish, and herbivorous fish.

[0013] Preferably, in step S2, when counting the number of functional group taxa, benthic animals are classified according to the feeding type, and the feeding types include predators, borers, scrapers, grazers, and filter feeders.

[0014] Preferably, in step S1, when collecting fish, 10 - 20 adult fish are collected for each sampling point.

[0015] Preferably, the collected adult fish are carnivorous fish, covering all carnivorous fish groups at the sampling point; optionally, when the number of carnivorous adult fish is less than 10, all carnivorous adult fish are collected and the dominant groups of omnivorous or herbivorous adult fish are selected; optionally, when the number of carnivorous adult fish is less than 10 and there is no obvious dominant group among omnivorous or herbivorous fish, different types of fish at the sampling point can be supplemented; in short, 10 - 20 adult fish samples need to be ensured.

[0016] Preferably, in step S4, the scatter distribution range is connected in a rectangular manner.

[0017] Preferably, in step S4, the method of drawing a scatter plot and connecting the scatter points includes using languages such as Python and C++ to write code to process the data.

[0018] Preferably, in step S5, first calculate the trophic level of each fish, and then calculate its average value to obtain the average trophic level of fish; the formula for calculating the trophic level of each fish is

[0019] where δ 15 N sample represents the nitrogen isotope ratio of fish, δ 15 N baseline represents the nitrogen isotope ratio of the reference organism, and Δδ 15 N represents the trophic enrichment factor.

[0020] Optionally, the reference organism is zooplankton.

[0021] Optionally, the trophic enrichment factor is 3‰ - 4‰.

[0022] Optionally, the aquatic organisms include phytoplankton, zooplankton, benthic animals, aquatic plants, and fish.

[0023] In the method for evaluating the integrity of aquatic organisms in river and lake water systems provided by the present invention, in the step S1, the time of collection should avoid the period of reproduction and release and avoid after heavy rain, so as to ensure that the captured aquatic organisms can accurately reflect the characteristics of aquatic organisms in the river and lake water systems to be evaluated; and no less than 3 sample points should be arranged during sampling, respectively covering the upstream, midstream, downstream of the river (section) to be evaluated or the coastal zone and the center of the lake (reservoir) of the lake (reservoir).

[0024] The method of collecting phytoplankton and zooplankton includes using a plankton net for collection. Typically, but not limitedly, the plankton nets of 25# and 13# are tied to bamboo poles or ropes, with the net mouth facing forward, and dragged in an "8" shape under the water surface at each collection point for 3 to 5 minutes, and then slowly lifted out of the water to concentrate the water sample in the collection tube at the bottom of the net, open the collection tube piston, and inject the sample into the sample bottle. For clean water bodies with low density of phytoplankton and zooplankton, repeat the above operation for no less than 30 times. For water bodies with relatively high nutrients, the number of repeated operations can be reduced as appropriate.

[0025] Methods for collecting benthic animals include using a mud sampler and a Sobel net for collection. Typically but not limitedly, the method may be as follows: make the bottom of the Sobel net sampling frame close to the riverbed and aquatic flora, drag it from downstream to upstream along a river section 150 to 250 meters in length, wash all benthic animals in the sampling frame into the net bag, then stir the bottom of the sampling frame with a small iron shovel, all bottom and benthic animals should be collected into the sampling net bag, pick out the benthic animals with pointed tweezers and immediately put them into the sampling bottle; look through the stones at the sampling point, pick out the benthic animals attached to them with pointed tweezers and put them into the sampling bottle; collect the bottom mud with a mud sampler, pour the collected bottom mud into a basin, filter it through a 60-mesh metal sieve to remove mud and debris, and pick out the benthic animals visible to the naked eye on the sieve into the sampling bottle with tweezers.

[0026] Methods for collecting aquatic plants include manual harvesting, which is typical but not limited, and can be specifically: selecting dominant aquatic plants at the collection point, emergent plants such as Poaceae, Typhaceae, Cyperaceae, Polygonaceae, etc. that grow in water can be collected directly by hand; floating leaf plants can be cut by stems and leaves with a knife; floating plants can be directly collected with a hand net with a handle; submerged plants can be collected with a rake or a drag hook.

[0027] The method of collecting fish includes using ground traps and nets, which are typically not limited to specific areas. Specifically, the fishing net or ground trap is placed in an area rich in fish at the collection point to catch fish.

[0028] The method for evaluating the integrity of aquatic organisms in river and lake water systems provided by the present invention comprises the following steps: 15 N, δ 13The pretreatment steps of C are existing methods. Typically and non - restrictively, specifically, they include: filtering phytoplankton with a 100 - μm sieve cloth and taking the filtrate, taking the tissue samples of zooplankton remaining on the sieve cloth, culturing them in distilled water for 3 h, separately filtering the filtrate and the tissue samples cultured in distilled water onto 2 GF / C filter membranes, drying them at 60 °C for 36 - 48 h, scraping off the tissue samples, and storing them sealed. For aquatic plants, take tissue samples, cut them into pieces with scissors and dry them in the cold for 24 h, take them out, mash them, and store them sealed. For benthic animals, classify and take their tissue samples according to functional group taxa, cut them into pieces, dry them in the cold for 24 h or dry them at 60 °C for 24 - 48 h, grind them after drying and sieve them through a sieve with a mesh size of 60 - 80 meshes, and store them sealed. The steps for processing fish tissue samples include cutting open a part of the skin on one side of the fish body with a scalpel, then peeling off the skin with forceps. After the muscle is exposed, take a small piece of muscle, > 15 g, cut it into pieces and dry it in the cold for 24 h or dry it at 60 °C for 24 - 48 h, grind it after drying and sieve it through a sieve with a mesh size of 60 - 80 meshes, and store it sealed. The sealed containers include sealed vials, centrifuge tubes or plastic bags.

[0029] For the method for evaluating the integrity of aquatic organisms in river - lake water systems provided by the present invention, in step S3, when testing δ 15 N, δ 13 C, existing methods are used. Typically and non - restrictively, specifically, it includes using a stable isotope ratio mass spectrometer for determination. The mass of the sample used is ≥0.2 g. The reference substances used for analysis are V - PDB (PeeDeeBelemnite) and nitrogen in the air respectively, and the standard substance is the internationally common IAEA - N - 1. To ensure the accuracy and precision of the experimental results, every 10 samples are measured repeatedly, and the analysis precisions of the carbon and nitrogen stable isotope ratios are 0.2‰ respectively.

[0030] The technical solution of the present invention has the following advantages:

[0031] The method for evaluating the integrity of aquatic organisms in river - lake water systems provided by the present invention includes the following steps: S1: Collect aquatic organisms; S2: Count the number of functional group taxa of benthic animals and fish; S3: Test δ 15 N, δ 13 C of the collected aquatic organisms; S4: Use δ 13 C as the abscissa and δ 15 N as the ordinate, draw a scatter plot classified by aquatic organism types, connect the scatter points to obtain the distribution ranges of different aquatic organism types, and calculate the overlapping degree; the overlapping degree is the union of the distribution ranges of δ 15 N, δ 13 C of phytoplankton and zooplankton, and the distribution ranges of δ 15 N, δ 13Proportion of the overlapping area of the C distribution range; S5: Calculate the average trophic level of fish; S6: Evaluate the food web structure of aquatic organisms in rivers and lakes, evaluate the integrity of aquatic organisms in the water system according to the number of functional group taxa, the degree of overlap, and the average trophic level of fish. The evaluation criteria are as follows: a comprehensive score > 85 is rated as excellent, 85 ≥ comprehensive score > 70 is rated as good, 70 ≥ comprehensive score > 50 is rated as medium, 50 ≥ comprehensive score ≥ 30 is rated as poor, and comprehensive score < 30 is rated as inferior; the comprehensive score = 0.3 × the score of the number of functional group taxa + 0.4 × the score of the degree of overlap + 0.3 × the score of the average trophic level of fish. This method is a method for comprehensively evaluating a certain water body, which can effectively reflect a long feeding history and a complete feeding process, so as to evaluate the integrity of aquatic organisms in river and lake water systems, indicate the changes in the water ecosystem, and provide guidance for subsequent water ecological protection and restoration work. Specifically, this method reflects its population diversity through the number of aquatic biological functional group taxa, reflects the length of the aquatic biological food chain transfer through the fish trophic level, reflects the feeding redundancy through the overlap degree between the carbon and nitrogen isotope distributions of fish and the carbon and nitrogen isotope distributions of zooplankton and phytoplankton, and comprehensively reflects the quality of the integrity of aquatic organisms in the target water body through these three aspects, and gives clear evaluation criteria, with the advantages of simple operation and avoiding randomness. In addition to considering the transfer characteristics on the food chain, this method also considers the integrity of the aquatic biological functional group, indicating whether the water ecosystem is healthy or damaged, and can reflect both the aquatic biological structure and species diversity. Using carbon and nitrogen isotopes to assist in the evaluation, the metabolism of aquatic organisms will cause isotope fractionation. δ 13 C generally has an enrichment coefficient of 0 - 1‰ along the food chain transfer, and δ 15 N generally has an enrichment coefficient of 3‰ - 4‰ at each trophic level during the transfer process on the food chain. Through δ 15 N, the number of transfer levels of aquatic organisms in this area can be reflected, so as to reflect the complexity of its food web structure; using δ 15 N and δ 13 C distribution matrices to reflect the degree of overlap, and the degree of overlap increases with the increase in the availability of resources and the redundancy of the river food web. Individual species change their feeding behaviors due to available resources, thus accurately reflecting the food web structure. Description of the Drawings

[0032] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0033] Figure 1 δ of different types of aquatic organisms obtained in Example 1 of the present invention15 N, δ 13 C scatter plot and interval distribution rectangle;

[0034] Figure 2 are the δ of different aquatic organisms obtained in Example 1 of the present invention 15 N, δ 13 C numerical bar chart;

[0035] Figure 3 is the trophic level bar chart of different fish obtained in Example 1 of the present invention;

[0036] Figure 4 are the δ of different aquatic organism types obtained in Example 2 of the present invention 15 N, δ 13 C scatter plot and interval distribution rectangle;

[0037] Figure 5 are the δ of different aquatic organisms obtained in Example 2 of the present invention 15 N, δ 13 C numerical bar chart;

[0038] Figure 6 is the trophic level bar chart of different fish obtained in Example 2 of the present invention;

[0039] Figure 7 are the δ of different aquatic organism types obtained in Example 3 of the present invention 15 N, δ 13 C scatter plot and interval distribution rectangle;

[0040] Figure 8 are the δ of different aquatic organisms obtained in Example 3 of the present invention 15 N, δ 13 C numerical bar chart;

[0041] Figure 9 is the trophic level bar chart of different fish obtained in Example 3 of the present invention;

[0042] Figure 10 are the δ of different aquatic organism types obtained in Example 4 of the present invention 15 N, δ 13 C scatter plot and interval distribution rectangle;

[0043] Figure 11 are the δ of different aquatic organisms obtained in Example 4 of the present invention 15 N, δ 13 C numerical bar chart;

[0044] Figure 12 is the trophic level bar chart of different fish obtained in Example 4 of the present invention. Detailed implementation manners

[0045] The following embodiments are provided to better further understand the present invention. It is not limited to the described optimal embodiment, and does not constitute a limitation on the content and protection scope of the present invention. Any method that is the same as or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior art features falls within the protection scope of the present invention.

[0046] For those embodiments where specific experimental steps or conditions are not indicated, the operations or conditions of the conventional experimental steps described in the literature in this field can be followed. For the reagents or instruments whose manufacturers are not indicated, they are all conventional reagent products that can be obtained through commercial purchase.

[0047] Experimental equipment

[0048] Stable isotope ratio mass spectrometer: Manufacturer Thermo Fisher Scientific, USA, Model MAT253.

[0049] Example 1

[0050] This example provides a method for evaluating the aquatic biological integrity of river and lake water systems. The sampled water area is the mountainous river section of the Yongding River Basin. The Yongding River mainly relies on natural runoff and externally diverted Yellow River water, with a water depth of 0.5 - 2 m, a flow velocity of 0.3 - 1.2 m / s, and the water quality is generally stable at Class III - IV. The sampling period is August 2022 (summer), and a total of 30 sampling points are arranged.

[0051] (1)Collect aquatic organisms at each sampling point. The specific operation is as follows: Attach the No. 25 and No. 13 plankton nets to a bamboo pole or rope respectively, with the net mouth facing forward. Drag them in an "8" shape under the water surface at each sampling point for 4 minutes, then slowly lift them out of the water to concentrate the water sample into the collection tube at the bottom of the net. Open the piston of the collection tube and inject the sample into the sample bottle. In waters with relatively low density and clean plankton and aquatic plants, repeat the above operation no less than 30 times. In waters with relatively high nutrient salts, the number of repeated operations can be appropriately reduced. Press the bottom of the Surber net sampling frame tightly against the river bottom sediment and aquatic plant community, and drag it along a 200-meter-long river section from downstream to upstream. Wash all the benthic animals in the sampling frame into the net bag, then stir the sediment in the sampling frame with a small iron shovel. All sediment and benthic animals should be collected into the sampling net bag. Use pointed tweezers to pick out the benthic animals and immediately put them into the sampling bottle. Turn over the stones at the sampling point and pick out the attached benthic animals with pointed tweezers and put them into the sampling bottle. Collect bottom sediment with a sediment sampler, pour the collected bottom sediment into a basin, filter it through a 60-mesh metal sieve to remove sediment and debris, and pick out the visible benthic animals on the sieve with tweezers and put them into the sampling bottle. Select the dominant aquatic plants at the sampling point. Emergent plants such as Gramineae, Typhaceae, Cyperaceae, and Polygonaceae growing in water can be directly collected by hand, such as Typha minima in this basin; floating-leaved plants can be cut with a knife to obtain stems and leaves, such as Nymphaea tetragona in this basin; floating plants can be directly collected with a hand net with a handle, such as Lemna minor in this basin; submerged plants can be collected with a rake or drag hook, such as Myriophyllum verticillatum in this basin. Place a fishing net or fish trap in the area rich in fish at the sampling point for fishing. Select 10 - 20 adult fish caught as samples. The most preferred adult fish to be collected are carnivorous fish, covering all carnivorous fish groups at the sampling point; when the number of adult carnivorous fish is less than 10, collect all adult carnivorous fish and select the dominant groups of omnivorous or herbivorous adult fish; when the number of adult carnivorous fish is less than 10 and there is no obvious dominant group among omnivorous or herbivorous fish, supplement different types of fish at the sampling point; in short, it is necessary to ensure 10 - 20 adult fish samples.

[0052] (2)Count the number of functional group categories of the collected benthic animals and fish, which are benthic predators, benthic borers, benthic scrapers, benthic grazers, benthic filter feeders, omnivorous fish (Abbottina rivularis, Pseudorasbora parva, etc.), carnivorous fish (Culter erythropterus, Opsariichthys bidens), a total of 7 types;

[0053] (3)Test the δ 15 N, δ 13C. First, pre-treat the collected aquatic organisms; for phytoplankton, filter the filtrate with a 100-μm sieve silk, for zooplankton, take the tissue sample remaining on the sieve silk, keep it in distilled water for 3 h, filter the filtrate and the tissue sample in distilled water onto 2 GF / C filter membranes respectively, dry them at a low temperature of 60 °C for 40 h, scrape off the tissue samples and store them sealed; for aquatic plants, take the tissue samples, cut them into pieces with scissors and dry them in the cold for 24 h, take them out, crush them and store them sealed; for benthic animals, take the tissue samples according to the functional group categories, cut them into pieces, dry them in the cold for 24 h, take them out, grind them and pass them through an 80-mesh sieve, and store them sealed; for fish, take the tissue samples according to the species, cut open a part of the skin on one side of the fish body with a scalpel, then peel off the skin with forceps, after the muscle is exposed, take a small piece of muscle, about 20 g, cut it into pieces and dry it at a low temperature of 60 °C for 30 h, after drying, grind it and pass it through an 80-mesh sieve, and store it sealed. Measure the prepared samples using a stable isotope ratio mass spectrometer, with the mass of the samples used being 2 g, and the reference substances used for analysis being V-PDB (PeeDee Belemnite) and nitrogen in the air, and the standard substance being the internationally common IAEA-N-1; repeat the measurement for every 10 samples, and the analysis precision of the carbon and nitrogen stable isotope ratios is 0.2‰ respectively.

[0054] (4) Using δ 13 C as the abscissa and δ 15 N as the ordinate, use a Python program to draw a scatter plot classified by the type of aquatic organisms, connect the scatter distribution ranges in a rectangular manner, and the obtained image is as shown in Figure 1 . Obtain the distribution ranges of different types of aquatic organisms, calculate the union of the δ 15 N and δ 13 C distribution ranges of phytoplankton and zooplankton, and the overlapping area ratio of the δ 15 N and δ 13 C distribution ranges of fish, that is, the overlapping degree, is 9.26%.

[0055] (5) Calculate the average trophic level of fish. Draw a bar chart of the δ 15 N and δ 13 C values of different types of aquatic organisms, as shown in Figure 2 . The δ 15 N and δ 13 C values can be visually analyzed. Use the formula

[0056] to calculate the trophic level of each fish, where δ 15 N sample represents the nitrogen isotope ratio of fish, δ 15 N baseline represents the nitrogen isotope ratio of the reference organism. In this embodiment, the reference organism is zooplankton (the specific nitrogen isotope value is shown in Figure 2), Δδ 15 N represents the nutrient enrichment factor, which is taken as 3.4‰ in this embodiment. After calculation, a bar chart of the trophic levels of different fish species is drawn as Figure 3 shown, and then the average trophic level of the fish is calculated to be 2.57.

[0057] (6) Evaluate the integrity of aquatic organisms in the water system. The evaluation is carried out according to the following criteria: a comprehensive score > 85 is rated as excellent, 85 ≥ comprehensive score > 70 is rated as good, 70 ≥ comprehensive score > 50 is rated as medium, 50 ≥ comprehensive score ≥ 30 is rated as poor, and 30 > comprehensive score is rated as inferior; the comprehensive score = 0.3 × the score of the functional group type quantity + 0.4 × the score of the overlap degree + 0.3 × the score of the average trophic level of fish; the evaluation criteria for the score of the functional group type quantity are that when the number of functional group types > 6, it is 100 points, when the number of functional group types is 6, it is 70 points, when it is 4 or 5, it is 50 points, when it is 3, it is 30 points, and when the number of functional group types < 3, it is 0 points; the evaluation criteria for the score of the overlap degree are that when the overlap degree < 5%, it is 100 points, when 5% ≤ overlap degree < 30%, it is 70 points, when 30% ≤ overlap degree ≤ 50%, it is 30 points, when the overlap degree > 50%, it is 30 points, and when there is no fish, it is 0 points; the evaluation criteria for the score of the average trophic level of fish are that when the average trophic level of fish ≥ 3.5, it is 100 points, when 3.5 > average trophic level of fish ≥ 3, it is 70 points, when 3 > average trophic level of fish ≥ 2.5, it is 50 points, when 2.5 > average trophic level of fish ≥ 2, it is 30 points, and when there is no fish, it is 0 points. The obtained results are shown in Table 1.

[0058] Example 2

[0059] This embodiment provides a method for evaluating the integrity of aquatic organisms in a river-lake water system. The difference from Example 1 is that the sampled water area is the plain section of the Yongding River Basin. The water depth of the plain section of the Yongding River is 1 - 2 m, the flow velocity is 0.3 - 0.5 m / s, and the water quality is generally stable at Class IV; in (2), the number of functional group types of the benthic animals and fish collected is 6, namely benthic predators, benthic borers, benthic scrapers, benthic grazers, omnivorous fish (Abbottina rivularis, Pseudorasbora parva, Micropercops swinhonis, etc.), and carnivorous fish (Culter erythropterus); the image obtained in (4) is as Figure 4 shown, and the overlap degree is 10.15%; in (5), the δ 15 N, δ 13 C numerical bar chart of different types of aquatic organisms is as Figure 5 shown, and the bar chart of the trophic levels of different types of aquatic organisms obtained is as Figure 6 shown, and the average trophic level of the fish is calculated to be 2.79; the results of the evaluation in (6) are shown in Table 1.

[0060] Example 3

[0061] This embodiment provides a method for evaluating the integrity of aquatic organisms in river and lake water systems. The difference from Embodiment 1 is that the sampled water area is a mountainous river in the Chaobai River Basin, mainly with natural runoff, the water depth is 0.2 - 1 m, the flow velocity is 0.3 - 0.8 m / s, and the water quality is generally stable at Class II - III; (2) The number of functional group taxa of the benthic animals and fish collected is 7, namely benthic predators, benthic borers, benthic scrapers, benthic grazers, benthic filter feeders, omnivorous fish (Rhodeus ocellatus, Acheilognathus chankaensis, etc.), and carnivorous fish (Channa argus, Opsariichthys bidens, Culter erythropterus); (4) The obtained image is as Figure 7 shown, with an overlap degree of 0%; (5) The δ 15 N, δ 13 C value bar charts of different aquatic organism types are as Figure 8 shown, and the trophic level bar charts of different aquatic organism types are as Figure 9 shown. The average trophic level of fish is calculated to be 2.38; (6) The results obtained from the evaluation are shown in Table 1.

[0062] Embodiment 4

[0063] This embodiment provides a method for evaluating the integrity of aquatic organisms in river and lake water systems. The difference from Embodiment 1 is that the sampled water area is a plain river in the North Canal Basin, mainly with reclaimed water, the water depth is 1 - 2 m, the flow velocity is < 0.3 m / s, and the water quality is generally stable at Class IV - V; (2) The number of functional group taxa of the benthic animals and fish collected is 7, namely benthic predators, benthic borers, benthic scrapers, benthic grazers, benthic filter feeders, omnivorous fish (Paramisgurnus dabryanus, Carassius auratus, Zacco platypus, etc.), and carnivorous fish (Odontobutis potamophila, Silurus asotus); (4) The obtained image is as Figure 10 shown, with an overlap degree of 53.73%; (5) The δ 15 N, δ 13 C value bar charts of different aquatic organism types are as Figure 11 shown, and the trophic level bar charts of different aquatic organism types are as Figure 12 shown. The average trophic level of fish is calculated to be 3.22; (6) The results obtained from the evaluation are shown in Table 1.

[0064] Table 1

[0065]

[0066] Analysis of the images and Table 1 in the embodiments shows that in the water bodies of different spatial latitudes, with large geographical and ecological gradients in the Yongding River Basin, Chaobai River Basin, and North Canal Basin, the trophic levels are generally between 0 and 4, and the δ 13 C is generally distributed between -30‰ and -10‰, and the δ 15The N of the population is evenly distributed between 0‰ and 18‰. The characteristics of aquatic organisms in different types of river channels show great differences: the δ 13 C range shows certain differences among aquatic organisms at different trophic levels in the Yongding River Basin and the Chaobai River Basin, but shows a large degree of overlap in the Beiyun River Basin, which reflects the changes in the feeding relationships of aquatic organisms in different basins. The δ 15 N generally shows an upward trend as the trophic level of aquatic organisms increases, but the upward trends in different distribution areas show significant differences. In the Yongding River Basin and the Chaobai River Basin, the δ 15 N generally shows a significant stepwise upward trend, and the δ 15 N between different trophic levels has a small intersection, while in the Beiyun River Basin, the δ 15 N shows a large-range superimposed upward trend. Especially for fish with different spatial distributions in the mountain channels of the Yongding River Basin, the plain channels of the Yongding River Basin, the mountain channels of the Chaobai River Basin, and the plain channels of the Beiyun River Basin, the δ 15 N ranges are 7.55‰ - 17.93‰, 10.53‰ - 16.35‰, 7.72‰ - 15.33‰, and 5.47‰ - 15.40‰ respectively, and the mean values are 13.03‰, 13.21‰, 11.98‰, and 9.15‰ respectively. The δ 15 N of high-trophic-level consumers in different regions shows significant differences. The δ 15 N of fish in the river channels of the Chaobai River and the Yongding River Basin is generally higher than that in the river channels of the Beiyun River Basin. From the rectangular distribution of the δ 15 N and δ 13 C intervals, it can be seen that different basins show different upward trends. The mountain channels of the Yongding River Basin and the mountain channels of the Chaobai River Basin generally show an "L"-shaped stepwise upward trend, the plain channels of the Yongding River Basin show a -shaped upward trend, and the Beiyun River Basin shows a "│"-shaped upward trend. The overlapping situations of the δ 15 N and δ 13 C intervals among different aquatic organisms in different basins also show significant differences. The overlapping proportions of fish and benthic animals in the mountain channels of the Yongding River Basin, the plain channels of the Yongding River Basin, the mountain channels of the Chaobai River Basin, and the plain channels of the Beiyun River Basin are 51.18%, 39.32%, 25.76%, and 47.96% respectively, and the overlapping proportions with planktonic animals and plants are 9.26%, 10.15%, 0%, and 53.73% respectively. In the Beiyun River Basin, the δ 15 N and δ 13 C distribution intervals of fish and other aquatic organisms show a large-range overlap.

[0067] Use the Beijing local standard DB11 / T 1722-2020 Technical Specification for Aquatic Ecosystem Health Assessment and the Ministry of Water Resources standard SL / T 793-2020 Guidelines for River and Lake Health Assessment to evaluate the aquatic biological integrity of each water area in the embodiments respectively, and compare the results with those obtained by the method in the present invention, as shown in Table 2. It can be seen that the three methods generally show strong consistency. Compared with the Beijing local standard and the Ministry of Water Resources standard, the method in the present invention has better discrimination, and is also more concise in operation and has strong repeatability.

[0068] Table 2

[0069]

[0070] Obviously, the above embodiments are only examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or variations derived therefrom are still within the protection scope of the present invention.

Claims

1. A method for evaluating the integrity of aquatic organisms in river and lake water systems, characterized in that, It includes the following steps: S1: Collect aquatic organisms; S2: Count the number of functional group taxa of benthic animals and fish; S3: Test the δ of the aquatic organisms collected 15 N, δ 13 C; S4: Using δ 13 C as the abscissa and δ 15 N as the ordinate, plot a scatter diagram classified by aquatic organism type, connect the scatter points to obtain the distribution ranges of different aquatic organism types, and calculate the overlap degree; The degree of overlap is the union of the distribution ranges of δ 15 N and δ 13 C of phytoplankton and zooplankton, and the overlapping area ratio of the distribution ranges of δ 15 N and δ 13 C of fish; S5: Calculate the average trophic level of fish; S6: Evaluate the food web structure of aquatic organisms in rivers and lakes, evaluate the integrity of aquatic organisms in the water system according to the number of functional group taxa, the degree of overlap, and the average trophic level of fish. The evaluation criteria are as follows: when the comprehensive score > 85, it is rated as excellent; when 85 ≥ comprehensive score > 70, it is rated as good; when 70 ≥ comprehensive score > 50, it is rated as medium; when 50 ≥ comprehensive score ≥ 30, it is rated as poor; when the comprehensive score < 30, it is rated as inferior; The comprehensive score = 0.3 × the score of the number of functional group taxa + 0.4 × the score of the degree of overlap + 0.3 × the score of the average trophic level of fish.

2. The method for evaluating the integrity of aquatic organisms in river and lake water systems according to claim 1, characterized in that, The evaluation criteria for the score of the number of functional group taxa are as follows: when the number of functional group taxa > 6, it is 100 points; when the number of functional group taxa is 6, it is 70 points; when it is 4 or 5, it is 50 points; when it is 3, it is 30 points; when the number of functional group taxa < 3, it is 0 points; And / or, the evaluation criteria for the score of the degree of overlap are as follows: when the degree of overlap < 5%, it is 100 points; when 5% ≤ degree of overlap < 30%, it is 70 points; when 30% ≤ degree of overlap ≤ 50%, it is 30 points; when the degree of overlap > 50%, it is 30 points; when there is no fish, it is 0 points; And / or, the evaluation criteria for the score of the average trophic level of fish are as follows: when the average trophic level of fish ≥ 3.5, it is 100 points; when 3.5 > average trophic level of fish ≥ 3, it is 70 points; when 3 > average trophic level of fish ≥ 2.5, it is 50 points; when 2.5 > average trophic level of fish ≥ 2, it is 30 points; when there is no fish, it is 0 points.

3. The method for evaluating the integrity of aquatic organisms in river and lake water systems according to claim 1, characterized in that, In step S2, when counting the number of functional group taxa, fish are classified according to carnivorous fish, omnivorous fish, and herbivorous fish.

4. The method for evaluating the integrity of aquatic organisms in river and lake water systems according to claim 1, wherein In step S2, when counting the number of functional group taxa, benthic animals are classified according to feeding types, and the feeding types include predators, borers, scrapers, grazers, and filter feeders.

5. The method for evaluating the integrity of aquatic organisms in river and lake water systems according to claim 1, characterized in that, In step S1, when collecting fish, 10 - 20 adult fish are collected for each sampling point.

6. The method for evaluating the integrity of aquatic organisms in river and lake water systems according to claim 5, characterized in that, The adult fish are carnivorous fish, covering all carnivorous fish groups at the sampling points. Optionally, when the number of adult carnivorous fish is less than 10, all adult carnivorous fish are collected and the dominant groups of omnivorous or herbivorous adult fish are selected.

7. The method for evaluating the integrity of aquatic organisms in river and lake water systems according to claim 1, characterized in that, In step S4, the scatter distribution range is connected in a rectangular manner.

8. The method for evaluating the integrity of aquatic organisms in river and lake water systems according to claim 1 or 7, characterized in that, In step S4, the method of drawing a scatter plot and connecting the scatter points includes using Python and C++ to write code to process the data.

9. The method for evaluating the aquatic biological integrity of river and lake water systems according to claim 1, wherein In step S5, first calculate the trophic level of each fish species, and then calculate its average value to obtain the average trophic level of the fish. The formula for calculating the trophic level of each fish species is where δ 15 N sample represents the nitrogen isotope ratio of the fish, and δ 15 N baseline represents the nitrogen isotope ratio of the reference organism, and Δδ 15 N represents the trophic enrichment factor; Optionally, the reference organism is zooplankton; Optionally, the nutrient enrichment factor is 3‰ - 4‰.

10. The method for evaluating the integrity of aquatic organisms in river and lake water systems according to any one of claims 1 to 9, characterized in that, The aquatic organisms include phytoplankton, zooplankton, benthic animals, aquatic plants, and fish.

Images