Zinc and copper distribution in excretory organs of the dogfish Scyliorhinus canicula and chloride cell response following treatment with zinc sulphate

Zinc and copper levels in the gills, kidney and intestine of the dogfish Scyliorhinus canicula L. collected in a 80 to 120 m deep zone close to Barcelona (Spain) during the months of February-March 1981 were measured by atomic absorption spectrophotometry after subacute (10 ppm Zn for 3 wk) and acute (80 ppm Zn for 24 h) treatment with ZnSO4. Individuals exposed to 80 ppm Zn accumulated Zn in the gills, whereas no significant increase in Zn content was found in the kidney or intestine. No differences in the Cu content of any of these tissues were found. Dogfish exposed to 10 ppm Zn for 3 wk displayed an increase in Zn content of the gills, kidney and intestine. An increase in the Cu concentration of the gills was also recorded which may suggest that Cu, and hence Zn and other heavy metals, are excreted via the gills when the kidney and intestine are overloaded. A light-microscopic study of the gill epithelium was carried out on dogfish treated with 10 ppm Zn for 3 wk, 80 ppm Zn for 24 h and 175 ppm Zn for 14 h, and chloride cell response was quantified. Chloride cells increased in number after each treatment, even appearing in the secondary lamellae following treatment with 175 ppm Zn. It is suggested that the chloride cell may excrete bivalent ions when dogfish are exposed to an excess of bivalent salts. © 1981 Springer-Verlag.