Developing a statistical-weighted index of biotic integrity for large-river ecological evaluations

Area of Science:

• Environmental Science
• Microbial Ecology
• River Ecology

Background:

• Current ecological assessment methods lack efficiency, accuracy, and universality for large river systems.
• Large rivers require tailored evaluation metrics due to geographical, ecological, and seasonal variations.
• There is an urgent need for novel assessment tools for watershed-scale river health.

Purpose of the Study:

• To develop a bacteria-weighted index of biotic integrity (lrBW-IBI) for assessing the ecological health of large rivers.
• To utilize compositional and functional characteristics of sediment bacterial communities for ecological assessment.
• To establish a new tool for comprehensive assessment and restoration of large river ecosystems.

Main Methods:

• Developed the lrBW-IBI based on sediment bacterial communities from 33 sections of the lower Yangtze River.
• Determined five key metrics using range, responsiveness, and redundancy tests.
• Applied Principal Component Analysis (PCA), entropy method, criteria importance through intercriteria correlation, and random forest to calculate weighted coefficients.

Main Results:

• The optimal lrBW-IBI incorporated relative abundance of Latescibacteria, Gemmatimonadaceae, Nitrospira spp., Rhizobiales, and nitrogenase NifH.
• PCA-based lrBW-IBI classified river sections as excellent (12.12%), good (24.24%), moderate (39.39%), and relatively poor (24.24%).
• Ecological status showed a gradual decline from upstream to downstream, with no significant seasonal variation.

Conclusions:

• The developed lrBW-IBI provides a novel and effective tool for assessing the ecological health of large rivers.
• Microbial ecological indices are crucial for understanding and managing river ecosystem health.
• Findings highlight the importance of considering spatial gradients in river ecological assessments.