Parasitism reduces oxidative stress of fish host experimentally exposed to PAHs

Some parasites are known to bioaccumulate some environmental pollutants within their host. We hypothesized that these may be beneficial for hosts in polluted environments. experimentally increased long-term (five weeks) exposure polycyclic aromatic hydrocarbons (PAHs, three levels: 0.1X, 1X, 10X exposure) European chubs (Squalius cephalus) were naturally infected or uninfected with acanthocephalan parasites. monitored PAHs levels fish tissues, as well oxidative stress, telomere length and condition indices. Although parasite infection did not significantly reduce the of PAH metabolites host status was explained by parasitism pollution levels. Oxidative damage exposed low (0.1X) but decreased at higher (10X), thus corroborating our hypothesis. Meanwhile, antioxidant capacity differ response nor exposure. Despite this imbalance status, experimental increase compromise length, body condition, survival fish. This study provides first evidence outcome host-parasite interactions can shift from negative positive pollutant increases.