EOHA ASM 2026

Abstract

Background

Fish are effective bioindicators of aquatic ecosystem health status, reflecting anthropogenic pressure, pathogen exposure, and consumer risk.

Objectives

To assess potential risks for human and aquatic-dependent wildlife in the heavily anthropized Lake Varese (Northern Italy), five commercially and ecologically relevant species were investigated: pike (Esox lucius italicus), pike-perch (Sander lucioperca), European perch (Perca fluviatilis), tench (Tinca tinca), and wels catfish (Silurus glanis).

Methods

A total of 59 specimens sampled during 2024 underwent morphological and anatomopathological examinations, bacteriological cultures, parasitological investigations involving transillumination and molecular identification (ITS region), and virological screening for major fish pathogens using EPC and BF2 cell lines. Per- and polyfluoroalkyl substances (PFASs) and heavy metals (Cd, Hg, Pb) were quantified in skeletal muscle using LC-MS/MS and ICP-MS QQQ, respectively.

Results

Among the detected biological agents, zoonotic pathogens were identified. Bacterial growth was detected in 49.2% of specimens; 93.1% of isolates were Aeromonas spp. (A. sobria, A. caviae, A. hydrophila) and 6.9% Pseudomonas spp.. Mycobacterium hiberniae, a non-tuberculous mycobacterium, was isolated from wels catfish. Eustrongylides excisus was detected in 16.9% of fish, involving all species except tench, representing the first report in Lake Varese. No viral pathogens were detected. Heavy metals were within EU regulatory limits. EU-regulated PFASs were generally below legal limits, except for PFOS in three larger pike specimens, which showed slightly elevated but non-alarming concentrations. Non-EU-regulated PFASs were detected at generally low levels, although higher cumulative concentrations were observed in pike-perch, showing values up to one order of magnitude higher than those of other species.

Conclusions

Species-specific bioaccumulation trends, evidence of PFAS circulation in the environment, and the detection of zoonotic bacterial and parasitic agents support the need for continuous, site-specific surveillance in freshwater ecosystems. Fish confirm their role as effective bioindicators for integrated environmental and human health risk assessment in heavily anthropized environments.