Abstract

The concept of a reference condition is increasingly used to describe benchmarks against which current condition is compared. This study defines criteria that represent reference sites for assessing highland streams in four major river basins of Ethiopia. Twenty a priori criteria were chosen as representative for Ethiopian highlands and they reflect some aspects of naturalness and address wide range of human disturbances. The most relevant criteria were those related to point and diffuse source of pollution, land use change, riparian vegetation, and river morphology. Of 104 study sites 22 were selected as reference based on established criteria and benthic macro-invertebrate (BMI) derived metrics were used for validation. BMI distribution in a scatter plot showed different level of degradation between reference and impaired sites. Moreover, biotic score established for Ethiopian highland streams revealed that 95% of a priori reference sites were within the range of ‘high’ ecological status and the scores showed high discrimination efficiency (above 93%) between reference and impaired sites. Reference criteria proposed in this study can be considered as valuable parameters to implement biomonitoring program in Ethiopian highland river ecosystems where true pristine areas are nonexistent as a result of different human activities and urbanization.

Key Words: Reference sites, Biomonitoring, Highland streams, A Priori criteria

DOI: https://ejesm.org/doi/v10i7.10