Macrophyte- and Macrozoobenthic-Based Assessment in Rivers: Specificity of the Response to Combined Physico-Chemical Stressors

The importance of adequate biological assessments rivers based on aquatic assemblages is essential to establish recovery measures. Macrophyte and macroinvertebrate communities react differently in time response strength diverse stressors. Our hypothesis was that each group a result specific combined abiotic factors stressor’s impact. To address the above, both quality elements (BQEs) values ecological ratio (EQR) were studied relation four parameters five physico-chemical Discrepancies more than one degree between status Bulgarian river sites determined using macrophytes macrozoobenthos discussed. RDA analysis showed altitude had determining role shaping abundance macrophyte communities. Aquatic flora richness positively correlated with nitrogen enrichment fauna—with biochemical oxygen demand (BOD). Nutrients shading most significant for evaluation defined macrozoobenthos. Macrophyte-based EQR related concentration shading, while macroinvertebrate-based better at coarser substrates. Among tested stressors, mainly total BOD explained lower macrophyte-based assessment half sites. In conditions increased BOD, but remaining range good status, as primary producers gave faster stronger response. Despite differences assessment, BQEs have higher phosphorus.