| In this study,biological integrity index was used to evaluate the health status of water ecosystem in Liao River basin.In 2020 and 2021,seven sampling sites in the Liao River Basin were sampled regularly for four times and evaluated by F-IBI,P-IBI,Z-IBI and B-IBI,respectively.The research results provide data support for environmental protection and pollution control policy formulation in Liao River Basin.In May 2020(spring),September 2020(autumn),May 2021(summer)and September 2021(autumn),a total of 3565 fish species belonging to 31 species,33 genera and 4 orders were collected from 7 sites(1 reference point and 6 damage points)in the Liao River Basin.There were 929 in spring 2020,1,111 in fall 2020,970 in spring 2021 and 555 in fall 2021.Through the analysis and screening of 23 candidate indicators,the f-IBI index system of each quarter was finally constructed.The f-IBI index values were obtained by using 1,3 and 5 assignment methods,and the health assessment of Liao River Basin was conducted in the spring and autumn of2020 and 2021 respectively.The results showed that the health status of Liao River basin was general,and the evaluation results of point 1,5 and 7 were poor or below for two consecutive years.The overall score of point 2 and Point 3 in each season was higher than sub-health level,which was similar to the previous results,indicating that F-IBI is feasible to evaluate the health of Liao River and can provide a basis for water ecological health evaluation of Liao River basin.A total of 119 species of phytoplankton from 8 phyla were identified in this study.Among them,98 species of 6 phyla were collected in spring 2020,101 species of 8 phyla were collected in autumn 2020,92 species of 7 phyla were collected in spring 2021,and 93 species of 7 phyla were collected in autumn 2021.The p-IBI index values were obtained by using 1,3 and 5 assignment methods,and the health assessment of Liao River Basin was conducted in the spring and autumn of 2020 and2021 respectively.The evaluation results showed that the health evaluation of points 5and 7 in each season was at average or below level,and the overall health status of points 2,3 and 4 in each season was high,indicating that the evaluation results of Liao River Basin were average and similar to the results of F-IBI,indicating that the p-IBI health evaluation could accurately reflect the status of Liao River Basin.A total of 42 species of zooplankton in 4 groups were identified in this study.Among them,32 species in 4 categories were collected in the spring of 2020,34 species in 4 categories in the autumn of 2020,29 species in 4 categories in the spring of 2021,and 30 species in 3 categories in the autumn of 2021.Z-ibi index values were obtained by using 1,3 and 5 assignment methods,and river health assessment was conducted for the Liao River basin in spring and autumn of 2020 and 2021 respectively.The results showed that many points were in poor or very poor health,and only point 3 was in good health.The main reason for this evaluation result is that some evaluation indexes cannot distinguish the reference area from the damaged area,so they are not suitable for evaluating the merits and shortcomings of water bodies.In the end,they are not suitable for evaluating the merits and shortcomings of water bodies.In the end,there are only a few indexes that constitute z-IBI index system.Z-ibi has a relatively small number of evaluation indicators,which need to be supplemented and improved continuously,and combined with other biological integrity indicators to make its evaluation more comprehensive.In this study,42 species of benthic animals were identified in 6 classes of 3 phyla.Among them,29 species from 3 phyla were collected in spring 2020,34 species from3 phyla were collected in autumn 2020,36 species from 3 phyla were collected in spring 2021,and 25 species from 3 phyla were collected in autumn 2021.The b-IBI index values were obtained by 1,3 and 5 assignment methods,and the river health was evaluated in the spring and autumn of 2020 and 2021.The results show that the health status of Liao River basin is good as a whole.Compared with F-IBI and P-IBI,b-IBI health evaluation of Liao River Basin has a higher health degree,and the points of average health level and above are significantly increased.In this study,by comparing various IBI evaluation systems,the scoring trends of fish,benthic animals and phytoplankton biointegrity index are relatively consistent,indicating that it is scientific and feasible to use biointegrity index to evaluate the river health level of Liao River.However,z-IBI has few evaluation indexes,which is different from other evaluation systems.In the future,it is suggested that these four biological indicators should be integrated to evaluate river health status,so as to make the evaluation results more reasonable and reliable,and provide reference for establishing river health evaluation system in northern China. |
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