Life-history Responses of Daphnia pulex with Exposure to Aluminum Sulfate

Abstract

Life table experiments with ten Daphnia clones were conducted to assess responses to three concentrations (0.05 mg 1⁻¹ A1, 0.30 mg 1⁻¹ A1, and 0.50 mg 1⁻¹ A1) of aluminum sulfate (alum), reflecting a general range that might be encountered in lake restoration treatments. Alum is frequently employed for phosphorus inactivation in lake restoration and management applications. Experimental Daphnia clones originated from a lake currently being treated with alum, from a lake treated with alum over twenty years ago, and from a pond with no prior alum additions. When exposed to laboratory alum-conditioned media, clones from the lake with ongoing alum treatment exhibited higher age-specific survivorship, higher fecundity, and faster growth rates compared with clones having less recent or no prior exposure. Our results suggest the possibility that Daphnia may exhibit adaptive strategies that heighten survivorship and fecundity when exposed to sub-lethal chemical stresses. Results also indicate that clone origin and previous exposure to chemicals is an important consideration in Daphnia bioassays.

Key Words:

• alum
• aluminum sulfate
• Daphnia
• Daphnia pulex
• zooplankton