Aquatic Toxicology 40 (1998) 123 -140 Autometallographed metal content in digestive cells of winkles: a cost-effective screening tool for monitoring Cu and Zn pollution Manu Soto *, Ifiaki Quincoces, Xabier Lekube, Ionan Marig6mez Bidqgicr Zelulurm Ada, Zoologiu etu Animali Zrluh Dinurnika Suila, Zienci Ftrkulitrrrrr. Euskol Herriko Unihrrtsitrrtru. 644 P. K., E-48080 Biho. Bmyuc (buntr!~, Sptrir~ Received 11 March 1996; revised 24 January 1997: accepted 12 June 1997 Abstract The amount of black silver deposits (BSDs) revealed by autometallography in several tissues of marine winkles (Littorinu littorea) exposed to sublethal concentrations of copper (01) and zinc (Zn) was semi-quantified using a light microscope. No significant change in the amount of BSDs was recorded in the cell types comprising the gill and mantle tissues. Changes in the amount of BSDs in cytoplasmic granules of some epithelial cells and in connective tissue pore cells were related to the body burdens of Cu and Zn, but, due to the high background signal produced by physiological Cu and Fe, the level of BSDs in these cell types may be very variable. In contrast, the amount of BSDs found in the digestive cell lysosomes is an excellent indicator of exposure to Cu, and the amount of BSDs found in the basal laminae of digestive tubules increases with increasing Zn exposure. However, the amount of BSDs reaches a threshold value, with no further increases being detected. Nevertheless, the semi-quantitative evaluation of BSDs in digestive cell lysosomes and basal laminae is proposed as an index for routine screening of metal pollution. Such an index may serve as a complementary approach to conventional chemical analyses, which could then be avoided when autometallography indicates a low bioavailability of metals in the environment. 0 1998 Elsevier Science B.V. Keyworci.s: Autometallography; Basal laminae of digestive tubules; Black silver deposits ( zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA BSDs) ; Digestive cells; Metal bioavailability index 1. Introduction It is well known that marine molluscs accumulate metals from seawater to reach tissue concentrations several orders of magnitude above the environmental levels *Corresponding author. Tel.: 0044647700 (Ext. 2422): fax: 0044648500; e-mail: gbpmaali@lg.ehu.es 0166-445X/98/$19.00 0 1998 Eisevier Science B.V. All rights reserved PIf SO166-445X(97)00055-6