Macroinvertebrate Community Response to Gradient of Organic Pollution in Agricultural Drainage Canals

Abstract

Agricultural drainage canals frequently receive elevated organic pollutant loads originating from fertilizer runoff, livestock waste, domestic discharge, and agricultural processing activities, leading to significant deterioration of aquatic ecosystem health and biodiversity. The present study investigates the response of macroinvertebrate communities to gradients of organic pollution in agricultural drainage canals under varying environmental conditions. The research focuses on evaluating changes in macroinvertebrate diversity, abundance, community structure, and ecological tolerance in relation to organic pollution intensity and water quality variation. Experimental analysis was conducted through seasonal biological sampling and physicochemical assessment of canal water to examine the influence of dissolved oxygen, biochemical oxygen demand, nutrient concentration, organic matter accumulation, and sediment characteristics on macroinvertebrate distribution patterns. Results demonstrate that increasing organic pollution levels significantly alter macroinvertebrate community composition, resulting in reduced species diversity and dominance of pollution-tolerant taxa in highly contaminated canal sections. The study further reveals that sensitive aquatic organisms decline substantially under elevated organic loading conditions due to oxygen depletion and habitat degradation. Comparative assessment of biological indices and water quality parameters confirms the effectiveness of macroinvertebrate communities as reliable bioindicators for evaluating ecological condition and pollution stress in agricultural drainage systems. In addition, spatial analysis identified clear ecological gradients corresponding to variations in anthropogenic contamination and nutrient enrichment.