Sulfide species and total sulfide toxicity in the shrimp Crangon crangon

The toxicity of total sulfide and individual sulfide species at different pH values were studied in Crangon. crangon. The toxicity is evaluated both from external concentrations and internal sulfide concentrations and pH. Internal sulfide concentrations are calculated according to a diffusion model. C. crangon is very sensitive to sulfide having a LT(50) of around 1 hour at 20 mu M total sulfide (pH 8). During sulfide exposures it is exclusively H2S which diffuses into C. crangon, and sulfide toxicity is dependent on the concentration of H2S (i.e., pH dependent). No HS- toxicity was found, The correct quantification of sulfide concentration in exposure experiments are concluded to be H2S concentration. Exposed to increasing sulfide concentrations, C. crangon shows a distinct pattern of behavior which is correlated to hemolymph H2S concentration; at 0.1 mu M hemolymph H2S C. crangon starts to swim, at 0.2 mu M hemolymph H2S C. crangon starts to panic (i.e., abdominal constrictions) and at 0.4 mu M hemolymph H2S C. crangon becomes paralysed.