Phytoplankton biological integrity index-based cascade development river ecosystem health condition evaluation method

Abstract

The invention provides a cascade development river ecosystem health condition evaluation method based on a phytoplankton biological integrity index, and belongs to the field of river ecosystem protection. The invention provides a method for evaluating the health condition of an existing cascade development river ecosystem and the limitation and deficiency of long-term tracking monitoring evaluation of the existing cascade development river ecosystem health condition evaluation method. Sampling survey method based on phytoplankton biological integrity, phytoplankton biological integrity index evaluation basic index system, phytoplankton biological integrity index evaluation selection index system construction and phytoplankton biological integrity index (P-IBI) Through the four parts of the cascade development river ecosystem health condition evaluation criterion system, a clear, complete, detailed and quantifiable evaluation criterion system is provided for cascade development of river water ecosystem health condition change and river ecosystem long-term tracking, monitoring and evaluation. Therefore, a scientific, simple, easy and economical evaluation method is provided for optimizing a river cascade development scheme and carrying out river ecosystem health condition evaluation and fixed-point long-term tracking monitoring.

Description

Technical Field

[0001] The invention provides a method for evaluating the health status of a cascade-developed river ecosystem based on a phytoplankton biological integrity index, and belongs to the technical field of river ecosystem protection and evaluation. Background Art

[0002] (1) Definition and connotation of phytoplankton biointegrity index

[0003] Phytoplankton, as the most important primary producer of aquatic ecosystem, has its species composition, structure and abundance significantly affected by changes in aquatic ecosystems and water conservancy project construction. The rise in water temperature in the reservoir area, the extension of hydraulic retention time and the enrichment of nutrients brought about by the cascade development of rivers can cause the massive reproduction of phytoplankton and lead to eutrophication of water bodies. Therefore, phytoplankton communities can be used as indicator biological groups of changes in the ecosystem of cascaded development rivers.

[0004] The Phytoplankton index of biological integrity (P-IBI) is widely used in the United States, the European Union and other places to evaluate the health of aquatic ecosystems. However, it is affected by the climate, river hydrology and biota of different regions. Therefore, the construction and selection of the index indicator system need to be continuously improved and perfected to be applicable to different rivers and research areas.

[0005] (2) Research status of phytoplankton biointegrity index evaluation system

[0006] In 2023, the Ministry of Ecology and Environment issued the "Technical Guidelines for Water Ecological Monitoring - Biological Monitoring and Evaluation of Lakes and Reservoirs (Trial)" (HJ1296-2023), which recommended the use of phytoplankton to establish a biological integrity index and conduct water ecological status monitoring. In recent years, many related studies have used the phytoplankton biological integrity index to evaluate the health of aquatic ecosystems. However, tracking the current status of related research shows that there are relatively few studies in China that use the phytoplankton biological integrity index evaluation system to conduct health evaluation of cascade development river ecosystems, and a phytoplankton integrity index evaluation indicator system based on long-term tracking and monitoring of cascade development rivers has not yet been established. For example:

[0007] 1) Zhou Yanfeng, Wang Dongwei, He Licong and others conducted an evaluation of the water ecological health of the middle reaches of the Huaihe River based on the plankton integrity index. The study constructed a phytoplankton biological integrity index evaluation system based on the survey results of phytoplankton and water environment quality in three hydrological periods, and selected indicators for the normal water period (11), the flood season (3), and the dry season (11) to construct the phytoplankton biological integrity index, and calculated the health status of the water ecosystem in the middle reaches of the Huaihe River based on this. The phytoplankton biological integrity evaluation index system constructed in the article is suitable for plain rivers in eastern my country such as the Huaihe River, but is not suitable for the assessment of the health status of cascade development river ecosystems in the southwestern mountainous areas of my country (Wetland Science, 2024, 22(4), pp477-486);

[0008] 2) Gao Xingchen, Zhang Qi, Su Wei and others conducted an ecological health assessment of the lower reaches of the Jinsha River based on the phytoplankton biointegrity index. The study conducted a phytoplankton biointegrity assessment before the lower reaches of the Jinsha River were put into operation (2017-2018), and screened out a phytoplankton integrity assessment system for the lower reaches of the Jinsha River consisting of five core parameters, including the total number of taxa, the number of cyanobacteria taxa, the proportion of diatom taxa, the cell density of diatoms, and the proportion of cell density of green algae. The phytoplankton integrity assessment index system constructed in the paper has a short monitoring period and only covers the data before the commissioning of each cascade in the lower reaches of the Jinsha River. It lacks data after the commissioning of each cascade, and is not suitable for the evaluation of the health status of the river ecosystem in the cascade development in southwest my country and the needs of long-term follow-up monitoring at fixed points (Journal of Water Ecology, 2025, 46(1): pp11-19).

[0009] 3) Wu Zhaoshi and Wang Changhui published a river water quality evaluation method based on the phytoplankton integrity index, which evaluates and grades river water quality based on the phytoplankton integrity index. The phytoplankton integrity index consists of total phytoplankton density, chlorophyll a and Odum index. The phytoplankton integrity index is suitable for river water quality evaluation. The candidate indicators do not include phytoplankton species composition and richness index and biodiversity index. The number of evaluation indicators is small, and the selected indicators are not suitable for the assessment of the status of cascade development river ecosystems in southwest my country (China, CN108562708A);

[0010] 4) Zhang Xiaowei, Zhang Lijuan and Yang Jianghua published a phytoplankton integrity assessment method based on environmental DNA macrobarcoding technology. This method is based on the results of phytoplankton monitoring using environmental DNA macrobarcoding, including the determination of reference points and damaged points, environmental DNA sample collection, eDNA macrobarcoding biological monitoring, and the definition and calculation of candidate biological indicators based on eDNA macrobarcoding monitoring. This method relies on environmental DNA data collection and DNA barcoding and high-throughput sequencing technologies that have emerged in recent years. It is not applicable to the construction of phytoplankton biological integrity index based on long-term sequence fixed-point monitoring, and the indicators finally selected are not applicable to the assessment of the status of cascaded river ecosystems in Southwest my country (China, CN113393131A);

[0011] In summary, rivers in southwest my country are rich in water. In recent years, with the large-scale cascade development, river ecosystems and their habitat conditions have undergone tremendous changes. It is urgent to study and establish a guiding and operational evaluation method for the health status of cascaded river ecosystems based on the phytoplankton biological integrity index based on the above-mentioned background technology to provide support, so as to provide a scientific, simple, easy and economical evaluation method for optimizing river cascade development plans, conducting river ecosystem health status evaluation and fixed-point long-term tracking monitoring, and protecting and restoring river ecosystems. Summary of the invention

[0012] (1) Purpose of the Invention

[0013] The present invention is created to address the limitations and deficiencies of existing methods for evaluating the health status of river ecosystems in cascade development and their long-term follow-up monitoring and evaluation. The present invention provides a method for evaluating the health status of water ecosystems in cascade development rivers based on the phytoplankton biological integrity index. It includes four parts: a sampling survey method based on phytoplankton biological integrity, a basic indicator system for evaluating the phytoplankton biological integrity index, a construction of a candidate indicator system for evaluating the phytoplankton biological integrity index, and a criterion system for evaluating the health status of river ecosystems in cascade development based on the phytoplankton biological integrity index (P-IBI). The present invention provides a clear, complete, detailed, and quantifiable evaluation criterion system for the changes in the health status of water ecosystems in cascade development rivers in southwest my country and long-term follow-up monitoring, and provides a scientific, simple, easy, and economical evaluation method for guiding the optimization of river cascade development plans and conducting regional river water ecosystem health status evaluation and fixed-point long-term follow-up monitoring.

[0014] (2) Technical solution

[0015] The technical solution adopted by the present invention to solve its technical problem is: to provide a method for evaluating the health status of a cascade-developed river ecosystem based on the phytoplankton biological integrity index, which comprises four parts: a sampling survey method based on phytoplankton biological integrity, a basic indicator system for evaluating the phytoplankton biological integrity index, construction of a candidate indicator system for evaluating the phytoplankton biological integrity index, and a criterion system for evaluating the health status of a cascade-developed river ecosystem based on the phytoplankton biological integrity index (P-IBI).

[0016] The sampling survey method based on phytoplankton biological integrity is characterized by the following features: phytoplankton community monitoring sections are arranged in the river sections below the dam site, above the dam site, at the end of the reservoir, and in the main tributary sections of the cascade development rivers; phytoplankton community monitoring surveys are carried out in three periods: the natural river state period, the water storage and inundation period of each cascade, and the normal water storage and operation period of the cascade; and the phytoplankton obtained from each monitoring section is species identified and counted.

[0017] The basic indicator system for evaluating the phytoplankton biological integrity index has the following characteristics: it is composed of two levels, four types of indicators and 18 sub-item basic indicators contained therein, wherein the first level contains four types of indicators: A1 biomass, A2 abundance, A3 biodiversity, and A4 nutritional status; the second level contains 18 sub-item basic indicators, which correspond to the four types of indicators A1, A2, A3, and A4, respectively. The specific corresponding relationships are as follows:

[0018] 1) A1 biomass: A11 phytoplankton biomass is a basic sub-item indicator;

[0019] 2) A2 abundance: 7 basic indicators including A21 abundance of Cyanobacteria, A22 abundance of Chlorophyta, A23 abundance of Bacillariophyta, A24 abundance of phytoplankton, A25 abundance ratio of Cyanobacteria, A26 abundance ratio of Chlorophyta, and A27 abundance ratio of Bacillariophyta;

[0020] 3) A3 Biodiversity: 6 basic indicators including A31 number of phytoplankton species / genera, A32 number of diatom species / genera, A33 Margalef index, A34 Shannon index, A35 Simpson index and A36 Pielou evenness index;

[0021] 4) A4 Nutritional status: four basic sub-indicators: A41 diatom quotient, A42 green algae quotient, A43 cyanobacteria quotient and A44 compound algae quotient.

[0022] The construction of the phytoplankton biological integrity index evaluation candidate index system includes the removal of redundant candidate indexes and the phytoplankton biological integrity index evaluation candidate index system, and the specific contents include:

[0023] 1) Removal of redundant indicators: The 18 basic indicators of phytoplankton biointegrity index evaluation in each survey section at different periods were counted respectively. The basic indicators with the number of occurrences of the basic indicators less than 5% were first removed, and then the Spearman rank correlation coefficients of the remaining basic indicators were calculated. For the basic indicators with rank correlation coefficients |R| greater than or equal to 0.70 and extremely significant correlation P < 0.01, one was retained as a candidate indicator;

[0024] 2) Phytoplankton Biointegrity Index Evaluation Candidate Index System: The sub-item basic indicators after the redundant indicators are removed are used to construct the phytoplankton Biointegrity Index Evaluation Candidate Index, including the following two levels, three categories of indicators and the five candidate indicators they contain, as shown below:

[0025]

[0026] The criterion system for evaluating the health status of river ecosystems in cascade development based on the phytoplankton biological integrity index (P-IBI) includes the determination of the distribution range of each candidate index for evaluation of the phytoplankton biological integrity index, the calculation of the score of each candidate index for evaluation of the phytoplankton biological integrity index, the calculation method of the phytoplankton biological integrity index (P-IBI) value, the grading standard of the phytoplankton biological integrity index and its corresponding river ecosystem health status, and the specific contents include:

[0027] 1) Determination of the distribution range of each candidate index for phytoplankton biointegrity index evaluation: Based on the values ​​of the five candidate indexes in each survey section at different periods, the minimum value C of each candidate index is calculated respectively. min , maximum value C max , 5% quantile value C 5％ , 95% quantile value C 95％ ;

[0028] 2) Calculation of the scores of each candidate index for phytoplankton biointegrity index evaluation: The calculation method for the scores of the candidate indexes for each survey section that is positively correlated with the health of the natural river ecosystem is: SM i =C i / C 95％ *100, the calculation method for the candidate index scores of each survey section that is negatively correlated with the health of the river ecosystem is SM i =(C max -C i ) / (C max -C 5％ )*100. If the calculated score of the candidate index is greater than 100, it will be counted as 100. If the calculated score is less than 0, it will be counted as 0.

[0029] 3) Calculation method of phytoplankton biological integrity index (P-IBI) value: That is, the score of each candidate index of the phytoplankton biological integrity index is added up and a simple arithmetic average is taken to obtain the phytoplankton biological integrity index P-IBI value of the monitoring section to be evaluated;

[0030] 4) The classification standard of phytoplankton biological integrity index and its corresponding river ecosystem health status. The health status of river ecosystem is judged according to the calculated phytoplankton biological integrity index P-IBI value according to the following evaluation criteria: when 81≤P-IBI value≤100, the evaluation grade is excellent, indicating a relatively natural and original river ecosystem; when 61≤P-IBI value≤80, the evaluation grade is good, indicating that the river ecosystem is disturbed by relatively low intensity human activities; when 41≤P-IBI value≤60, the evaluation grade is medium, indicating that the river ecosystem is disturbed by moderate intensity human activities; when 21≤P-IBI value≤40, the evaluation grade is poor, indicating that the river ecosystem is disturbed by high intensity human activities; when 1≤P-IBI value≤20, the evaluation grade is poor, indicating that the river ecosystem is seriously disturbed by human activities.

[0031] (3) Advantages and effects

[0032] The advantage of the present invention is that it has created a method for evaluating the health status of cascade-developed river ecosystems based on the phytoplankton biological integrity index, including a sampling survey method based on phytoplankton biological integrity, a basic indicator system for evaluating the phytoplankton biological integrity index, a candidate indicator system for evaluating the phytoplankton biological integrity index, and a criterion system for evaluating the health status of cascade-developed river ecosystems based on the phytoplankton biological integrity index (P-IBI). Its advantages and effects are reflected in the following aspects:

[0033] 1) The proposed sampling survey method based on phytoplankton biointegrity covers the river section below the dam site, the river section above the dam site, the river section at the end of the reservoir and the main tributaries. The monitoring period includes the natural river state period, the cascade impoundment flooding period and the cascade normal impoundment operation period. This survey method is suitable for the construction of phytoplankton biointegrity index of cascade development rivers and the fixed-point long-term tracking monitoring of the health status of river ecosystems;

[0034] 2) The proposed basic indicator system for evaluating the phytoplankton biological integrity index includes two levels and four types of indicators, including biomass, abundance, biodiversity, nutritional status and its 18 sub-item basic indicators, which provides a clear and complete evaluation indicator system for the evaluation of the health status of cascade development river ecosystems;

[0035] 3) The proposed phytoplankton biointegrity index evaluation candidate index system is constructed, including two levels of three types of indicators and the five candidate indicators they contain, providing a detailed and quantifiable evaluation criteria system for the evaluation of the health status of cascade development river ecosystems;

[0036] 4) The constructed evaluation criteria system for the health status of cascaded river ecosystems based on the phytoplankton biological integrity index (P-IBI) includes the determination of the distribution range of each candidate indicator for the phytoplankton biological integrity index evaluation, the calculation method of the phytoplankton biological integrity index (P-IBI) value, the phytoplankton biological integrity index grade classification standard and its corresponding river ecosystem health status, which provides a simple, easy and economical evaluation method for quantitative evaluation of the health status of cascaded river ecosystems and long-term follow-up monitoring and evaluation.

[0037] The present invention makes up for the technical deficiencies in the health status evaluation and long-term follow-up monitoring of water ecosystems in cascaded development rivers, fills the gap in the comprehensive evaluation method for the health status of water ecosystems in cascaded development rivers, and provides a scientific, simple, feasible and economical evaluation method for optimizing river cascade development plans, conducting river ecosystem health status evaluation and fixed-point long-term follow-up monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 :Basic indicator system for evaluating phytoplankton biological integrity index DETAILED DESCRIPTION

[0039] The following is a further explanation of the implementation of the present invention with reference to examples.

[0040] The Lancang River is about 2160 km long in China and has a drainage area of ​​17.4×10 4 km 2 , annual runoff 517.6×10 8 m 3, the mainstream is rich in hydropower resources, and a total of 14 cascade developments are planned in China. This section takes the Xiaowan and Manwan cascade development sections in the middle reaches of the Lancang River as specific implementation cases. Combined with the construction and operation plans of each cascade in the middle reaches of the Lancang River, the phytoplankton community surveys in the case study area were conducted in 1988 (natural river state period), 1997 (Manwan cascade water storage and inundation period), 2011 (Xiaowan cascade water storage and inundation period) and 2015-2016 (cascade normal water storage and operation period). The phytoplankton community survey sections in the middle reaches of the Lancang River include 10 sections from Xiaowan to Manwan in the mainstream and 1 section of the main tributary Heihui River. The 11 survey sections cover the river sections below the dam site, the river sections above the dam site, the river sections at the end of the reservoir, and the main tributary sections. Therefore, the 1988 survey is considered to represent the natural original state of the phytoplankton community in the middle reaches of the Lancang River. The surveys conducted in 1997 and 2011 are considered to represent the distribution of phytoplankton communities under the influence of the cascade impoundment process of Manwan and Xiaowan. The surveys conducted in 2015-2016 are considered to represent the distribution of phytoplankton communities under the influence of the cascade impoundment and normal operation of Xiaowan and Manwan.

[0041] The specific phytoplankton community survey method of this case is as follows: Due to the difference in the hydrological process of the Lancang River in the rainy season and the dry season, the phytoplankton survey in the study area was conducted in April of the dry season each year. The phytoplankton survey mainly used a 10L plexiglass water sampler to collect 3 water samples at the surface of the water body (0.5m) and mix them. Take 1L of water sample from the mixed water sample and store it in a plastic sampling bottle. At the same time, add 1.5% Luger's reagent and concentrate it to 30ml after standing for 48h. The enriched 30ml sample was brought back to the laboratory for identification and analysis under a microscope (magnification 400×). The identification of phytoplankton species was based on Hu Hongjun and Wei Yinxin ("Chinese Freshwater Algae-System, Classification and Ecology", Science Press, 2006), identified to the species or genus level, and the abundance of each taxonomic group of zooplankton was counted at the same time.

[0042] Combining current domestic and foreign research, based on the species composition characteristics, biodiversity, and nutritional status of the Lancang River phytoplankton, we selected four types of indicators at two levels and the 18 basic sub-items they contained to construct the basic indicator system for evaluating the biological integrity of the Lancang River phytoplankton. The specific calculation process of the 18 basic sub-items is as follows:

[0043] 1) A11 Phytoplankton biomass: The biomass of phytoplankton in the survey section is fresh biomass. The fresh biomass of each phytoplankton species is replaced by approximate geometric volume (1.00 g cm -3 ), calculate the fresh biomass of phytoplankton per unit volume of each survey section, and the unit is mg / L;

[0044] 2) A21 Cyanobacteria abundance: the number of phytoplankton individuals of the Cyanophyta in the survey section, measured in ind / L;

[0045] 3) A22 Chlorophyta abundance: the number of Chlorophyta phytoplankton individuals in the survey section, ind / L;

[0046] 4) A23 Bacillariophyta abundance: the number of Bacillariophyta phytoplankton individuals in the survey section, ind / L;

[0047] 5) A24 Phytoplankton abundance: The number of phytoplankton individuals in the survey section, including Cyanobacteria, Chlorophyta, Bacillariophyta, Rhodophyta, Cryptophyta, Dinophyta, Chrysophyta, Xanthophyta, and Euglenophyta, is calculated as ind / L;

[0048] 6) A25 Cyanobacteria abundance ratio: the ratio of Cyanobacteria abundance to total phytoplankton abundance in the survey section, expressed in %;

[0049] 7) A26 Chlorophyta abundance ratio: the ratio of Chlorophyta abundance to total phytoplankton abundance in the survey section, expressed in %;

[0050] 8) A27 Bacillariophyta abundance ratio, the ratio of Bacillariophyta abundance to total phytoplankton abundance in the survey section, expressed in %;

[0051] 9) A31 Number of phytoplankton species / genera: the number of phytoplankton species in the survey section, calculated at the species level of the phytoplankton classification system;

[0052] 10) A32 Number of Bacillariophyta species / genera: the number of Bacillariophyta phytoplankton species in the phytoplankton classification system of the survey section;

[0053] 11) A33 Margalef index: The calculation formula of the Margalef index (d) of the survey section is as follows:

[0054] d=(S-1) / lnN (1)

[0055] In the formula, N is the abundance of phytoplankton in the survey section, and S is the number of phytoplankton species in the survey section;

[0056] 12) A34 Shannon index: The calculation formula of the Shannon index (H′) of the survey section is as follows:

[0057]

[0058] Where n i is the abundance of the i-th taxonomic unit (species) of phytoplankton in the survey section, and N is the abundance of phytoplankton in the survey section;

[0059] 13) A35 Simpson index: The calculation formula of the Simpson index (1-λ) of the survey section is as follows:

[0060]

[0061] Where n i is the abundance of the i-th taxonomic unit (species) of phytoplankton in the survey section, and N is the abundance of phytoplankton in the survey section;

[0062] 14) A36 Pielou uniformity index: The calculation formula of the Pielou uniformity index (J′) of the investigated section is as follows:

[0063] J′=H′ / lg(S) (4) In the formula, H′ is the Shannon index of the survey section, S is the number of phytoplankton species in the survey section;

[0064] 15) A41 Diatom quotient: The calculation method of diatom quotient of the survey section is: Diatom quotient = number of species in Centricae of Diatoms / number of species in Pennatae of Diatoms;

[0065] 16) A42 Green algae quotient: The calculation method of green algae quotient of the survey section is: Green algae quotient = number of species in Chlorophyta / number of species in the order Desmidiales of Chlorophyta;

[0066] 17) A43 Cyanobacteria quotient: The calculation method of the cyanobacteria quotient of the survey section is: Cyanobacteria quotient = number of species in Cyanobacteria / number of species in Chlorophyta;

[0067] 18) A44 Composite algae quotient: The calculation method of composite algae quotient of the survey section is composite algae quotient = (number of species in Cyanobacteria + number of species in Chlorophyta + number of species in Centrophyta of Bacillariophyta + number of species in Euglenophyta) / number of species in Chlorophyta and Dysphaeriales.

[0068] In the process of constructing the candidate index system for phytoplankton biological integrity index evaluation, the values ​​of 18 sub-items of basic indicators for phytoplankton biological integrity index evaluation in each survey section at different periods were counted. In order to reduce the influence of redundant indicators, the basic indicators with the number of occurrences of sub-items of basic indicators less than 5% were first removed, and then the Spearman rank correlation was used to analyze the correlation coefficient and significance of the remaining sub-items of basic indicators. In this study, for the sub-items of basic indicators with Spearman rank correlation coefficient values ​​|R| greater than or equal to 0.7 and extremely significant correlation (P < 0.01), one was retained as a candidate indicator. Therefore, 13 basic sub-indicators including A11 phytoplankton biomass, A21 Cyanobacteria abundance, A22 Chlorophyta abundance, A23 Bacillariophyta abundance, A26 Chlorophyta abundance ratio, A31 number of phytoplankton species / genera, A32 number of Bacillariophyta species / genera, A34 Shannon index, A35 Simpson index, A36 Pielou evenness index, 42 Chlorophyta quotient, A43 Cyanobacteria quotient and A44 Complex algae quotient were eliminated as redundant indicators, and finally a total of 5 indicators were selected for the phytoplankton biological integrity index evaluation index system (Table 1).

[0069] Table 1 Calculation indicators for evaluating the health status of the river ecosystem in the middle reaches of the Lancang River based on the phytoplankton biological integrity index (P-IBI)

[0070]

[0071] Note: A positive correlation indicates a positive correlation with the health of the river ecosystem; a negative correlation indicates a negative correlation with the health of the river ecosystem.

[0072] Based on the phytoplankton biological integrity index (P-IBI) cascade development river ecosystem health evaluation criteria system, the health status of the river ecosystem in the middle reaches of the Lancang River was evaluated before and after the cascade development (Table 2). The results showed that the health status of the river ecosystem in the middle reaches of the Lancang River before the cascade development in 1988 was excellent; during the water storage and inundation period of the Manwan cascade development in 1997, the health status of the water ecosystem in the still water area in front of the dam was reduced to good, while the river section at the end of the reservoir and the Xiaowan section were still excellent; during the water storage and inundation period of the Xiaowan cascade development in 2011, the health status of the water ecosystem in the still water area in front of the dam and the tributary reservoir area was reduced to good, while the river section below the dam, namely the river section at the end of the Manwan reservoir, was still excellent; during the normal water storage and operation period of the cascade development from 2015 to 2016, the health status of the water ecosystem in the still water area near the dam in the Manwan section was reduced to moderate and good, while the river section at the end of the reservoir, namely the river section below the Xiaowan dam, remained excellent, and the health status of the water ecosystem in the still water area in front of the dam and the tributary reservoir area in the Xiaowan section was still good.

[0073] Table 2 Evaluation results of the health status of the river ecosystem in the middle reaches of the Lancang River based on the phytoplankton biological integrity index (P-IBI)

[0074]

[0075] Note: “-” indicates no survey.

[0076] Therefore, the above implementation cases show that the health status evaluation method of cascaded river ecosystems based on the phytoplankton biological integrity index (F-IBI) can provide a scientific, simple, easy and economical technical support for the quantitative evaluation of the health status of cascaded river water ecosystems and fixed-point long-term tracking monitoring and evaluation.

Claims

1. A method for evaluating the health status of cascade-developed river ecosystems based on the phytoplankton biological integrity index, which consists of four parts: a sampling survey method based on phytoplankton biological integrity, a basic indicator system for phytoplankton biological integrity index evaluation, a candidate indicator system for phytoplankton biological integrity index evaluation, and a criterion system for evaluating the health status of cascade-developed river ecosystems based on the phytoplankton biological integrity index P-IBI; The sampling survey method based on phytoplankton biological integrity is characterized by the following: Phytoplankton community monitoring sections were set up in the river sections below the dam site, above the dam site, at the end of the reservoir, and in the main tributaries of the cascade development rivers. Phytoplankton community monitoring surveys were carried out in three periods: the natural river state period, the flooding period of each cascade impoundment, and the normal impoundment operation period of the cascade. The phytoplankton species obtained from each monitoring section were identified and counted. The basic indicator system for evaluating the phytoplankton biological integrity index is: Its characteristics are as follows: It consists of two levels of four indicators and their 18 sub-item basic indicators. The first level includes four indicators: A1 biomass, A2 abundance, A3 biodiversity, and A4 nutritional status; the second level includes 18 sub-item basic indicators, which correspond to the four indicators A1, A2, A3, and A4 respectively; The specific corresponding relationships are as follows: (1) A1 biomass: A11 phytoplankton biomass is a basic sub-item indicator; (2) A2 abundance: 7 basic indicators including A21 abundance of Cyanobacteria, A22 abundance of Chlorophyta, A23 abundance of Bacillariophyta, A24 abundance of Phytoplankton, A25 abundance ratio of Cyanobacteria, A26 abundance ratio of Chlorophyta, and A27 abundance ratio of Bacillariophyta; (3) A3 Biodiversity: six basic indicators, including A31 number of phytoplankton species / genera, A32 number of diatom species / genera, A33 Margalef index, A34 Shannon index, A35 Simpson index, and A36 Pielou evenness index; (4) A4 Nutritional status: four basic sub-indicators: A41 diatom quotient, A42 green algae quotient, A43 cyanobacteria quotient, and A44 compound algae quotient; The construction of the phytoplankton biological integrity index evaluation candidate index system includes the removal of redundant candidate indexes and the phytoplankton biological integrity index evaluation candidate index system, and the specific contents include: 1) Removal of redundant indicators: The 18 basic indicators of phytoplankton biointegrity index evaluation in each survey section at different periods were counted respectively. First, the basic indicators with a frequency of less than 5% of the basic indicators were removed, and then the Spearman rank correlation coefficients of the remaining basic indicators were calculated. For the basic indicators with a rank correlation coefficient value |R| greater than or equal to 0.70 and a highly significant correlation P<0.01, one was retained as a candidate indicator; 2) Phytoplankton Biointegrity Index Evaluation Candidate Index System: The sub-item basic indicators after the redundant indicators are removed are used to construct the phytoplankton Biointegrity Index Evaluation Candidate Index, including the following two levels, three categories of indicators and the five candidate indicators they contain, as shown below: The criterion system for evaluating the health status of river ecosystems in cascade development based on the phytoplankton biological integrity index P-IBI includes the determination of the distribution range of each candidate index for evaluation of the phytoplankton biological integrity index, the calculation of the score of each candidate index for evaluation of the phytoplankton biological integrity index, the calculation method of the phytoplankton biological integrity index P-IBI value, the grading standard of the phytoplankton biological integrity index and its corresponding river ecosystem health status, and the specific contents include: a. Determination of the distribution range of each candidate index for evaluation of phytoplankton biointegrity index: Based on the values ​​of the five candidate indexes surveyed at each survey section in different periods, the minimum value C of each candidate index was calculated respectively. min , maximum value C max , 5% quantile value C 5％ , 95% quantile value C 95％ ; b. Calculation of the scores of each candidate index for phytoplankton biointegrity index evaluation: For each survey section that is positively correlated with the health of the river ecosystem, the calculation method for the candidate index score is SM i =C i / C 95％ *100, the calculation method for the candidate index scores of each survey section that is negatively correlated with the health of the river ecosystem is SM i =(C max -C i ) / (C max -C 5％ )*100. If the calculated score of the candidate index is greater than 100, it will be counted as 100. If the calculated score is less than 0, it will be counted as 0. c Calculation method of phytoplankton biological integrity index P-IBI value: That is, the scores of each candidate index for the phytoplankton biological integrity index are added together and a simple arithmetic average is taken to obtain the phytoplankton biological integrity index P-IBI value of the monitoring section to be evaluated; d. The classification standard of phytoplankton biological integrity index and its corresponding health status of river ecosystems. The health status of river ecosystems is judged according to the calculated phytoplankton biological integrity index P-IBI value according to the following evaluation criteria: when 81≤P-IBI value≤100, the evaluation grade is excellent, indicating a relatively natural and original river ecosystem; when 61≤P-IBI value≤80, the evaluation grade is good, indicating that the river ecosystem is disturbed by relatively low intensity human activities; when 41≤P-IBI value≤60, the evaluation grade is medium, indicating that the river ecosystem is disturbed by moderate intensity human activities; when 21≤P-IBI value≤40, the evaluation grade is poor, indicating that the river ecosystem is disturbed by high intensity human activities; when 1≤P-IBI value≤20, the evaluation grade is poor, indicating that the river ecosystem is seriously disturbed by human activities.

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