The influence of phenanthrene on the ionoregulatory toxicity of waterborne copper in mummichog (Fundulus heteroclitus) acclimated to seawater or freshwater

Abstract

Metals and polycyclic aromatic hydrocarbons (PAHs) frequently co-occur in coastal ecosystems, yet their combined effects on aquatic species are poorly understood. Exposure to waterborne copper (Cu) causes acute ionoregulatory disruptions, while phenanthrene (PHE) induces oxidative stress and may create complexes with metals or compromise epithelial integrity, potentially altering Cu uptake. My study assessed the individual and combined effects of Cu and PHE in seawater and freshwater on iono-and osmoregulation in mummichog (Fundulus heteroclitus) over 48 h. In seawater, Cu increased carcass sodium and chloride, while in freshwater it reduced both ions. Ammonia excretion declined in both salinities during the first 24 h. PHE had no effect alone and did not influence Cu toxicity in seawater, but in freshwater, it enhanced Cu-induced chloride loss. These findings suggest that PHE may enhance Cu toxicity in freshwater, highlighting the need to consider salinity and contaminant interactions in risk assessment.