Evaluation of river habitat integrity based on benthic macroinvertebrate-based multi-metric model

- The benthic macroinvertebrate multi-metric index (B-MMI) is developed to assess the ecological integrity.
- The ecological integrity of hydromophologic unit (HMU) types is assessed.
- The relations between environmental factors and B-MMI in sites and HMU types are analyzed.

Considering relationships between environmental factors and aquatic ecosystems, obtaining a clear understanding of river habitat integrity plays a key role in addressing habitats' disturbances. Since benthic macroinvertebrate assembly can reflect the benthic stream conditions, we assessed the river habitat integrity based on benthic macroinvertebrate multi-metric model. The development and application of Benthic macroinvertebrate multi-metric index (B-MMI) was based on samples collected from October to November 2014 at representative sites from upper to lower reaches in Luanhe River, Haihe River Basin, China. Hydromorphology, water quality and land use patterns were considered to define reference sites and metrics related to macroinvertebrate community composition, structure, function and tolerance to pollution were selected as candidate metrics. Then, Range, sensitivity and redundancy tests were used to select candidate metrics based on their ability to distinguish the reference and impaired sites. As the result, four core indicators were selected to build the B-MMI: EPT%, Tubificidae%, BI (Biotic Index), Collect-Gatherers%. The values of B-MMI ranged from 0.21 to 3.75 in 17 sites. Based on B-MMI values, the habitat integrity of 29% sites were in very poor status and 6% were in excellent status. The upper reaches were influenced by animal husbandry and tourism, while the lower reaches were influenced by urbanization and dams. More good habitats were located in middle reaches under less human disturbances. Overall, this B-MMI shows promise for developing biomonitoring tools to assess the habitat integrity of streams, to provide appropriate restoration strategies and policies.