Occurrence of mercury in Macrobrachium lanchesteri (de Man) (Crustacea, Decapoda) in Thailand [Sea food]

Herbivorous freshwater shrimps (Macrobrachium lanchesteri) were collected from a water course (river Chao Phraya , Bangkok) in front of a caustic soda factory, marshland behind a battery mill 2.5 km from the caustic soda factory, a channel near a chemical factory some distance from the caustic soda factory, and an urban canal 30 km north of Bangkok. The mean mercury concentrations (ppm fresh weight) in the shrimps were 0.08, 0.02, 0.02 and 0.007 ppm, respectively. The mercury concentrations of the carnivorous shrimp, M. rosenbergii (caught 60 km north of Bangkok), were lower than those of M. lanchesteri caught in the vicinity of the caustic soda factory in Bangkok. The high mercury concentration in the Bangkok shrimp could have been responsible for the increased level of mercury in the shrimp predator fish, Ophicephalus striatus. The possible dangers to public health are mentioned.