EXPERIMENTAL-STUDY OF THE COMBINED EFFECTS OF PH AND SALINITY ON THE BIOACCUMULATION OF INORGANIC MERCURY IN THE CRAYFISH ASTACUS-LEPTODACTYLUS

The combined effects of pH and salinity were investigated on the bioac cumulation of inorganic mercury in the Turkish crayfish Astacus leptod actylus, at the whole organism and organ levels. Effects on the ionic balance were also analysed during the acclimatization phase and after 3 and 15 days of exposure, via the direct route. The experimental prot ocol, based on a complete factorial design, took into account nine exp erimental conditions, resulting from the combination of three levels f or pH (6, 7.5 and 9) and for salinity (1, 10 and 100 mM Cl-). The resu lts showed an important Hg accumulation in the organs or tissues in di rect contact with the surrounding medium, e.g. gills-and carapace. The effects of the nine pH and salinity conditions were complex and varia ble from one organ to another. Correlations were studied between chemi cal species concentrations in the water (HgCl2, HgOHCl, HgCl3-, HgCl42 -, Hg(OH)(2)) and amounts of metal accumulated in the different organs . A positive correlation was found between the neutral species HgCl2 a nd metal accumulated in the gills and in the carapace. Perturbations o f the haemolymph ionic concentrations were no significant, except for Na+ after 3 days of exposure.