ACCUMULATION AND PHYSIOLOGICAL AND BIOCHEMICAL EFFECTS OF CADMIUM IN A SIMPLE AQUATIC FOOD-CHAIN

The toxicity of cadmium with regard to the vegetative reproduction of duckweed, Lemna gibba, grown in sterile culture, was determined. The E C(50) was found to be 800 ppb. Duckweed grown in 2.24 ppm cadmium (sup plied as cadmium nitrate) for 7 days accumulated 98.5% of the availabl e cadmium from the growth medium. Plants that had been grown for 7 day s in 2.24 ppm cadmium and control plants were fed to red swamp crayfis h, Procambarus clarkii, for 14 days. The concentrations of cadmium wer e measured in hepatopancreata and muscles of crayfish on Day 0 and in crayfish fed duckweed grown in cadmium for 14 days. Accumulation of th is metal in hepatopancreata increased 26-fold, i.e., 176.80 ppb on Day 0 to 4657.56 ppb on Day 14, and in muscles almost 7-fold, i.e., 6.75 ppb on Day 0 to 46.28 ppb on Day 14. Crayfish fed cadmium-containing d uckweed demonstrated inhibition (55% after 14 days of feeding) of acet ylcholinesterase activity in their central nervous tissue compared to crayfish fed cadmium-free duckweed. The ovarian index and total lipids content in the ovaries of crayfish fed cadmium-containing duckweed de monstrated significant increases on Day 14. (C) 1996 Academic Press, I nc.