Atrazine (ATZ) is a widely used herbicide that is prone to leaching into aquatic systems, raising concerns about their effects on non-target organisms. Freshwater mussels, as filter-feeding benthic biota, represent sensitive bioindicators of water quality. Hemolymph-based biomonitoring serves as a robust approach for evaluating aquatic pollution. This study aimed to assess responses of a suite of multi-biomarkers in hemolymph of the freshwater mussel Hyriopsis bialata dosed with sublethal ATZ concentrations: environmentally relevant levels (0.02 and 0.2 mg/L) and a high level (2 mg/L). Unexposed mussels served as controls. Hemolymph samples were collected periodically throughout the 28-day treatment period. Pooled hemolymph of separate sexes was subjected to analyses of the multi-biomarkers, classified into five groups: DNA damage and apoptosis, oxidative stress and antioxidant, energy and metabolism, neurotransmission machinery, and stress hormone. Generally, ATZ had no overt outcomes on the biomarkers. However, ATZ exposure resulted in a significant transient increase in malondialdehydes (MDA) in males and a significant temporary decrease in γ-aminobutyric acid receptors (GABAR) in both sexes; the latter showing an effect window over the course of Day 0 to Day 3. Overall, exposure to ATZ at the sublethal concentrations did not induce detectable alterations in the hemolymph biomarker responses. Hence, these findings provide a basis for utilizing bivalve hemolymph as a minimally invasive diagnostic matrix and highlighting the potential of biomarker-based surveillance for ecological health assessment in contaminated freshwater systems. • Bivalve hemolymph served as a powerful tool for assessing atrazine (ATZ) toxicity. • ATZ treatment caused a temporary increase in MDA levels in male mussels. • Early exposure to ATZ led to a transient decline in GABAR levels in both sexes. • Hemolymph biomarkers tended to show no significant changes following ATZ exposure.
Nuchan et al. (Sun,) studied this question.