Ecological condition, biodiversity and major environmental challenges in a tropical river network in the Bago District in South-central Myanmar: First insights to the unknown

•Myanmar has no system in place to assess ecological condition in rivers.•Rivers investigated were impacted by multiple stressors across spatial scales.•We applied macroinvertebrates as bioindicators and a proxy for biodiversity.•Land-use changes and organic pollution were primarily responsible for degradation.•Macroinvertebrate indices captured ecosystem stress in this tropical river network.