Interactions of methylmercury,cadmium, and salinity on regeneration in the fiddler crabs Uca pugilator,U. pugnax and U. minax

After multiple autotomy in the fiddler crabs Uca pugilator, U. pugnax and U. minax, both methylmercury and cadmium retard limb regeneration and ecdysis. When crabs in sea water are exposed to a mixture of both metals, the effect is increased, indicating that the two are interacting in an additive way. In 50% sea water (=15% S), the effects of cadmium are greatly intensified so that growth of limb buds is extremely slow, if it occurs at all. When methylmercury is present in the water at the same time, the severe effects of cadmium are somewhat ameliorated, indicating an antogonistic interaction of the two metals under these conditions. Adding additional calcium to the 50% sea water also decreased the severity of the cadmium effect, thus supporting the idea of a calcium-cadmium competition.