() Effects of cadmium, copper and zinc on the hatching success of brine shrimp (Artemia franciscana).
Brix, K.1, Sklavounos, S.2, Adams, W.3, Grosell, M.2, 1 EcoTox, Coral Gables, Florida, United States2 University of Miami, Miami, Florida, United States3 Rio Tinto, Murray, Utah, United States
ABSTRACT- While brine shrimp are generally considered relatively insensitive to metals, previous studies indicate that hatching success is unusually sensitive to metal exposure. These earlier studies suggest that brine shrimp hatching success can be affected by cadmium, copper and zinc exposures in the 5-10 mg/L range in artificial seawater. These results have implications for both ecological risk assessment and setting water quality standards for the Great Salt Lake. The objective of our study was to investigate whether these earlier studies were repeatable, and if not, understand the experimental design factors that controlled these earlier results. Three experimental design parameters were identified as potentially having effects on brine shrimp sensitivity: 1.) pretreatment of cysts with antibiotics, 2.) unusually low calcium and bicarbonate concentrations in the artificial seawater (approximately 10 and 20% of normal seawater, respectively), and 3.) the absence of dissolved organic carbon in the dilution water (compared to the Great Salt Lake which has 35 mg/L DOC). Our study investigated the effects of each of these parameters on the sensitivity of brine shrimp hatching success when exposed to metals. Studies to date indicate that the low toxicity values observed in previous studies cannot be repeated for cadmium and zinc (NOECs of 5,000 and 160 mg/L) while previous results for copper are repeatable (NOEC of 4 mg/L). These studies also show that pretreatment of cysts with antibiotics has no effect on their sensitivity to metals. Ongoing studies will investigate how low calcium/bicarbonate concentrations in the artificial dilution water and site-specific characteristics of Great Salt Lake water effect copper bioavailability and subsequent toxicity.
Key words: cadmium, copper, zinc, Artemia franciscana