UPTAKE OF LEAD, CADMIUM AND ZINC BY THE FAIRY SHRIMP, BRANCHINECTA-LONGIANTENNA (CRUSTACEA, ANOSTRACA)

Individuals of the fairy shrimp, Branchinecta longiantenna, were subjected to 5 concentrations (0.1 to 15 mg l-1) of Pb in diluted habitat water at 13-degrees-C. Lead concentrations (mg kg-1 wet weight) in the animals were determined at 2-day intervals by digestion in nitric acid followed by atomic absorption analysis. The shrimp were also subjected to 0.1 mg l-1 media of Cd and Zn, separately. Uptake rates by the fairy shrimp for the three metal ions at 0.1 mg l-1 were: 0.111, 0.0885, and 0.0460 mg kg-1 day-1 for Zn, Pb, and Cd, respectively. After 2 days in 1.0 mg l-1 Cd or Zn, the animals expired; but they survived for 8 days in a 10 mg l-1 Pb medium and for 2 days in 25 mg l-1 Pb. Lead uptake demonstrated a linear dependence on the Pb concentration in the media. Shrimp survived at much higher tissue accumulations of Pb compared to Zn and Cd. Estimated lethal doses were 20, 1.2-2.4, and 0.4-1.4 mg kg-1 wet weight for Pb, Zn, and Cd, respectively. Pb was found to be at much lower concentration than Cd or Zn in the natural pond water but between Cd and Zn levels in the sediment. Thus Cd and Zn probably present a greater threat to B. longiantenna than Pb, although Pb may be in higher concentration in the environment.