Heavy Metal Accumulation in Caohai Crayfish in Relation to Environmental Conditions

  Objective  Heavy metal accumulations in organs of crawfish at Caohai Lake in Guizhou were measured to determine the effect of environmental pollution, providing reference for the healthy cultivation of crayfish and scientific evaluation on the heavy metal contamination.

  Method  Samples of water, sediment and crayfish were collected from various locations on the lake for heavy metal determination. An experiment of live crayfish cultivated under enriched Cu²⁺ and Cd²⁺ conditions was conducted in the laboratory to generate a simulated heavy metal transfer model. The contents of Cu, Cd, Pb, Zn and Hg in the collected soil and crayfish samples as well as in the various organs of the cultivated crayfish were determined by atomic absorption spectrometry. Pearson correlation analysis and variance analysis were applied to analyze the data.

  Result  All 5 heavy metals were detected in the crayfish, sediment and water samples from the lake. The metal contents in the crayfish organs differed in the order of viscera > shell > meat. The Pearson correlation analysis showed that Cd, Pb and Zn in the sampled crayfish significantly correlated with those in the sampled sediment, but not the water samples.The heavy metal concentration in the viscera, but not in the shell, meat or claw, of the crayfish raised in the lab increased with increasing heavy metal addition to the water.

  Conclusion  The contamination of heavy metals in crayfish closely related to the conditions of the lake in which it lived. And, the heavy metal contents varied in different organs of the shellfish.