Ecophysiology and Mercury Accumulation of Rainbow Trout (Salmo gairdneri) When Exposed to Mercury in Various Concentrations of Chloride

Abstract

Rainbow trout (Salmo gairdneri) mortality was 100% when exposed to HgCl2 (2–10 μg∙Hg2+∙L−1) for 14 d in a natural low chloride medium. There was no mortality if the medium contained 100, 200, or 400 mg Cl−∙L−1 or more. Accumulation of mercury was highest in kidneys (0.65–13 μg∙g−1), spleen (0.31–4.2), gills (0.46–4.15), and liver (0.53–2.1) but accumulations differed for periods of exposure (14 or 42 d) and chloride concentration in the medium (100 or 200 mg Cl−∙L−1). In rainbow trout exposed to HgCl2 for 42 d, there were significant increases in plasma sodium level at 200 mg Cl−∙L−1 and significant decreases in plasma potassium, albumin, α1-globulin, and β-globulin levels in 100 mg Cl−∙L−1. No significant changes occurred in these parameters at other chloride concentrations or in erythrocytes, hematocrit, mean corpuscular volume, white blood cell counts, or chloride plasma levels. Although chloride concentrations in the media affect mercury accumulation by different organs as well as affecting physiological functions, there appears to be no direct relationship except for reduced mortality.