Akademik Veri Yönetim Sistemi
ECOTOXICOLOGY, cilt.35, sa.3, ss.1-14, 2026 (Scopus)
Cadmium (Cd) is a common aquatic contaminant that poses significant ecological risks by disrupting organismal functions and ecosystem balance. This study presents the first detailed evaluation of acute Cd toxicity in the medicinal leech Hirudo verbana Carena, 1820, a species of ecological, biomedical, and conservation importance listed under CITES. In a 96-hour semi-static bioassay with graded Cd exposures (0–32 mg/L), we determined an LC50 of 4.02 mg/L and observed a range of concentration-dependent behavioral and pathological responses, including erratic locomotion, excessive mucus secre tion, regurgitation, and penis prolapse. We introduced the Body Flexion Ratio (BFR) to quantify morphological responses to Cd-induced neurotoxic stress in leeches. Measured in dead individuals due to mobility challenges in live leeches, BFR reflects current toxic responses rather than predicting Cd toxicity. A positive correlation between BFR values and Cd con centrations suggests its potential applicability as a non-behavioral indicator in field-based ecotoxicological assessments. Concurrently, Cd exposure led to a marked decline in dissolved oxygen levels and increases in conductivity, total dissolved solids, and salinity, further intensifying physiological stress in exposed organisms. These abiotic shifts correlated with the intensity of toxic responses, implying a synergistic impact of chemical and environmental stressors. This study underscores the utility of medicinal leeches as bioindicators in freshwater ecotoxicology and highlights the necessity of integrating biotic responses, including BFR, with water chemistry and ecosystem health indicators for a more comprehensive and robust risk assessment. Given the dual pressures of habitat degradation and commercial harvesting, urgent conservation measures are warranted. Our findings contribute essential toxicity thresholds and highlight H. verbana as a model for studying sublethal pollutant effects in shallow freshwater ecosystems.