This study investigated heavy metal bioaccumulation, pollution sources, and human health risks in the Wujiang and Zhenjiang rivers, the major headwaters of the Beijiang River in southern China. Concentrations of 11 heavy metals (Fe, Mn, Ba, Zn, As, Cu, Ni, Cr, Co, Cd, Pb) in surface water, sediments, and the soft tissues of four bivalve species (Corbicula fluminea, Limnoperna fortunei, Unio douglasiae, and Anodonta woodiana) were determined. Results showed that surface water remained below pollution thresholds, whereas sediments in the Wujiang River exhibited moderate-to-heavy Cd, As, Pb, and Zn contamination linked to historical Pb-Zn mining. Among the two better-represented species, C. fluminea showed relatively high As and Zn concentrations, whereas L. fortunei showed relatively high Cu accumulation. Data for U. douglasiae and A. woodiana were treated as preliminary observations because of their limited sample sizes. Biota-sediment accumulation factor (BSAF) values indicated that Mn, Cu, Cd, Zn, Ni, and Cr were actively accumulated beyond sediment concentrations, whereas As and Pb showed limited sediment-to-biota transfer. Multivariate analysis of the two better-represented species indicated species-related differences in tissue metal profiles, with patterns consistent with both natural geogenic inputs and historical Pb-Zn mining activities. All four species posed potential non-carcinogenic health risks to consumers, with As and Mn as the dominant risk contributors. These findings underscore the necessity of multi-species biomonitoring and consumption advisories in mining-impacted watersheds.

Parasitic infections pose a significant threat to the wild population of Southern catfish (Silurus meridionalis) in Dongting Lake, yet the specific pathogen identity and epidemiological drivers remain unclear. This study combined morphological assessment, 28S rDNA molecular identification, and Generalized Linear Models (GLM) to elucidate the infection dynamics and pathogenicity of trematodes. Molecular analysis confirmed the pathogen as Isoparorchis eurytremus. GLM analysis revealed that apparent spatiotemporal variations in infection were actually sampling bias in fish host size structure; the total length was identified as the decisive predictor of infection risk. The infection probability followed a sigmoid growth pattern with a median infection length (L₅₀) of 70.4 cm, a phenomenon attributed to the host’s ontogenetic diet shift from insectivory to obligate piscivory. Anatomical observations indicated that the infection induced systemic pathology; beyond severe fibrosis and mechanical damage to the swim bladder, varying degrees of parenchymal lesions were evident in the liver, spleen, and kidney. These findings indicate that I. eurytremus infection in S. meridionalis is a size-dependent, accumulative process maintaining a homogenous high pressure across the lake ecosystem, necessitating a shift in perspective from localized lesions to systemic disease management.

Antibiotics and antibiotic resistance genes (ARGs) are widespread in aquatic ecosystems affected by climate variability, urbanization, and intensifying aquaculture. Yet parent-antibiotic concentrations and resistance-related genetic endpoints do not always vary in parallel across seasons, sites, or environmental compartments. This discrepancy matters for aquatic animals as ecological receptors, potential vectors, and targets for antimicrobial resistance monitoring and management. To examine whether transport, retention, and biological processes may contribute to these mismatches, we conducted a structured narrative review. We screened studies retrieved from Web of Science Core Collection, Scopus, and PubMed for paired measurements in aquatic systems. Of 98 field studies, 25 provided sufficient paired data for matched chemical–genetic assessment. Among these, 16 provided Moderate evidence and 9 provided Suggestive evidence for coupled, mismatched, or compartment-dependent responses. No study met the stricter criteria for field-supported legacy persistence. Seasonal reversals, spatial divergence, and differences among water, particles, and sediments suggest that water-column antibiotic concentrations alone are incomplete proxies for ARG abundance. Such measurements alone cannot assess ARG mobility or host context. Potential contributors include sediment and biofilm retention, extracellular DNA, hydrodynamic redistribution, horizontal gene transfer, transformation products, and co-selective stressors, although their relative roles remain unresolved. These findings support monitoring that combines chemical and genetic endpoints with information on sources, hydrology, compartments, and hosts to inform aquatic-animal risk assessment and management.