Chronic toxicity of arsenic to the Great Salt Lake brine shrimp, Artemia franciscana

We determined the chronic toxicity of arsenic (sodium arsenate) to the Great Salt Lake brine shrimp, Artemia franciscana. Chronic toxicity was determined by measuring the adverse effects of arsenic on brine shrimp growth, survival, and reproduction under intermittent flow-through conditions. The study commenced with <24-h-old nauplii, continued through reproduction of the parental generation, and ended after 28 days of exposure. The concentrations tested were 4, 8, 15, 31, and 56 mg/L dissolved arsenic. The test was conducted using water from the Great Salt Lake, Utah as the dilution water. Adult survival was the most sensitive biological endpoint, with growth and reproduction somewhat less sensitive than survival. The no observed effect concentration (NOEC) for survival was 8 mg/L, and the lowest observed effect concentration (LOEC) was 15 mg/L dissolved arsenic. The LOEC for growth and reproduction was greater than the highest concentration tested, 56 mg/L. Based on survival, the final chronic value (geometric mean of the NOEC and LOEC) was 11 mg/L dissolved arsenic. The F1 generation appeared to acclimate to the prior arsenic exposure of the parental generation and was significantly less sensitive than the parental generation. For example, survival for the F1 generation through day 12 was 100% in 56 mg/L dissolved arsenic, compared to 26% for the parental generation. Growth of the F1 generation was significantly less than that of the parental generation across all concentrations including the control, indicating a generational difference in brine shrimp growth rather than an arsenic effect. This study represents one of the few full life cycle toxicity tests conducted with brine shrimp.