Use of blood parameters in fish to assess acidic stress and chloride pollution in French running waters

The study investigated whether plasmatic parameters in fish such as Cl− content could serve as physiological indicators to evaluate water quality. The variations of plasma Cl− content in two fish species caught in a wide range of rivers representative of the hydrographic system of Lorraine (N-E France) were investigated. First, we studied autochthonous populations of chub (Leuciscus cephalus) which is a widespread species in the rivers of Lorraine. Organisms living in highly mineralised rivers (>1500 μS cm−1)––either naturally or due to salt mine contamination––showed plasma Cl− content significantly greater than organisms living in river with a lower mineralisation. Second, we investigated plasma Cl− content of brown trout (Salmo trutta fario) in poorly mineralised streams (<80 μS cm−1) with different degrees of acidification, both on autochthonous and transferred organisms. While indigenous trout maintained their Cl− content even in the acidic streams, transferred trout exhibited an important decrease of Cl− content after 48 h of exposure under acidic conditions.