Molar acute toxicity of eleven heavy metals on two marine clams: Tapes decussata and Venerupis aurea (bivalve mollusk phylum veneridae)

The following eleven heavy metal ions aluminum; tin (stannous), cadmium; lead; mercury; dichromate; manganese, nickel; cobalt; zinc; and copper were tested on the two bivalve clams Tapes decussata; and Venerupis aurea specimens taken from Temsah Lake at Ismailia. The acute 96 hr. LC50 values were deduced from dose probit regression lines. Tapes decussata proved to be more susceptible for toxicity by these eleven heavy metals. Molar LC50 values were calculated as a more precise criterion to compare the ions which widely vary in the ionic weight. Comparison showed that aluminum, tin, and mercury were the most hazardous ions to the two clam species, followed by cadmium, lead and cobalt as medium toxic; while nickel, zinc, cobalt, copper and manganese were relatively the least toxic. Generally, the highly acute toxic metals were also known to be of high capacity to accumulate and cause chronic toxicity to both the marine biota and the consumers. This confers importance of the acute toxicity assessment as a preliminary meaning criterion to detect and predict the acute and chronic hazardous chemicals in the environment.