Assessment of Aquatic Ecological Health in the Lower Jinsha River Based on Benthic Macroinvertebrate Integrity Index

Based on the aquatic ecological sampling data of benthic macroinvertebrates in the lower Jinsha River, an assessment of aquatic ecological health was conducted. A total of 42 benthic macroinvertebrate species were identified, with the total number and abundance distribution trends of benthic macroinvertebrates showing a consistent increase from the downstream reservoir area of the Jinsha River to the upstream protection area of the Yangtze River. Using IBM SPSS Statistics 26 software to analyze the distribution range, discriminant analysis, and redundancy analysis of candidate parameters, the Benthic Index of Biotic Integrity (B-IBI) index system for the study area was established. Three parameters were selected to construct the B-IBI index: total taxonomic richness, relative abundance of predator individuals, and Shannon-Wiener index. The scores for each index were calculated using a ratio method to determine the B-IBI values at each sampling site. The evaluation baseline value for the benthic macroinvertebrate integrity index was determined to be 5.42. The results of the aquatic ecological health assessment indicate that the water ecological health status in the upstream protection area of the Yangtze River is generally healthy, while the downstream reservoir area of the Jinsha River is in relatively poor condition. Moreover, the overall aquatic ecological health status gradually improves with increasing distance from the cascade reservoirs in the lower Jinsha River.