Ecological Health Assessment Of The Yiluo River Based On The Biological Integrity Index Of Planktonic Algae

Planktonic algae,as primary producers of aquatic ecosystems,are commonly used as indicator organisms for water environment assessment.As an important primary tributary of the Yellow River,the protection of the ecological health of the Yiluo River water body is of great significance for the sustainable development of the Yellow River basin.Based on field investigation,the physical and chemical factors of the Yiluo River environment and the structure of planktonic algae communities were analyzed,the water quality of the Yiluo River was evaluated with algae diversity index,comprehensive water quality index（WQI）,etc.By correlation analysis,discriminant analysis,and distribution range analysis respectively,and finally the core parameters of planktonic algae were obtained.Phytoplankton Index of Biotic Integrity（P-IBI）was conducted,and ecological health assessment on the water body of the Yiluo River was made.The comparative analysis of P-IBI and WQI indicates that P-IBI is suitable for the health assessment of the water ecosystem in the Yiluo River.This study provides important technical support for the health protection,sustainable development,and management of the water ecosystem in the Yellow River Basin.The main research results are as follows:1)During the research period,the overall water quality of the Yiluo River was weakly alkaline,and the permanganate index(COD_Mn)of each sampling point reached the Class II water standard;The variation range of total phosphorus（TP）in the Yiluo River Basin is between 0.023 and 0.33mg/L,and the TP content at the sampling points is within the II-IV water standard;The total nitrogen（TN）of the Yiluo River severely exceeds the standard,with7 sampling sections measuring TN content exceeding the Class V water standard.2)The comprehensive nutritional status index（TLI（Σ））of the Yiluo River ranges from31.1 to 52.8,and the TLI evaluation results show that the water bodies at the sampling section are in a medium nutritional state;The comprehensive water quality index（WQI（Σ））of the Yiluo River ranges from 65.6 to 87.2,and the WQI evaluation results show that the overall water quality of the Yiluo River is in good condition;The water quality evaluation results using the Shannon Wiener diversity index（H′）and Pielous uniformity index（J）showed that the water body of the Yiluo River was in a lightly polluted or unpolluted state,while the water quality evaluation results using the Margalef richness index method（D）showed that the water body of the Yiluo River was in a moderately polluted state.3)During the research period,a total of 52 species of planktonic algae from 8 phyla were collected in the Ilo River area,of which 21 species were found in the Chlorophyta,accounting for 42%of the total;The diatom phylum is the second phylum collected,with 12 species,accounting for 24%of the total phylum;The blue-green algae phylum ranks third,with a total of 5 species,accounting for 10%of the total phylum;There are 4 species in the phylum Euglenophyta,accounting for 8%of the total;The number of species in the phylum Cryptophyta is 3,accounting for 6%of the total;There are two similar species,accounting for4%,in the phylum Chrysophyta and phylum Chrysophyta;The phylum Xanthophyta has the least species,with only one species accounting for 2%.During the research period,the dominant species of planktonic algae were Chlorella and Microcystis in the phylum Chlorophyta,and Microcystis in the phylum Diatoma.4)Determine the reference point and damage point based on the Shannon index H’.Conduct correlation analysis,discriminant analysis,and distribution range analysis on the candidate parameters participating in the evaluation,and construct the Ilo River Biological Integrity Index P-IBI.The P-IBI index value of the Ilo River ranges from 2.84 to 4.19,with an average value of 3.05.The evaluation results show that the Ilo River is in a"sub healthy"state as a whole.Comparative analysis with WQI water quality assessment results shows that P-IBI is suitable for the health assessment of the Yiluo River ecosystem.