Effects of hardness and alkalinity in culture and test waters on reproduction of Ceriodaphnia dubia

Environmental Toxicology and Chemistry
By: , and 



Ceriodaphnia dubia were cultured in four reconstituted water formulations with hardness and alkalinity concentrations ranging from soft to the moderately hard water that is required by whole-effluent toxicity (WET) testing methods for culturing test organisms. The effects of these culture formulations alone and in combination with two levels of Cl-, SO42, and HCO3- on reproduction of C. dubia were evaluated with the standard three-brood test. Reproduction was significantly reduced when test waters had lower hardness than culture waters. However, reproduction was not significantly different when animals cultured in low-hardness waters were exposed to moderately hard waters. The hardness of the culture water did not significantly affect the sensitivity of C. dubia to the three anions. Conversely, increased hardness in test waters significantly reduced the toxicities of Cl- and SO42-, with HCO3- toxicity following the same pattern. Alkalinity exhibited no consistent effect on Cl- and SO42- toxicity. The physiological stress of placing animals cultured in moderately hard water into softer test waters might contribute to marginal failures of otherwise nontoxic effluents. The standard WET protocol should be revised to allow the culture of C. dubia under lower hardness conditions to better represent local surface water chemistries.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Effects of hardness and alkalinity in culture and test waters on reproduction of Ceriodaphnia dubia
Series title Environmental Toxicology and Chemistry
Volume 25
Issue 10
Year Published 2006
Language English
Contributing office(s) Patuxent Wildlife Research Center
Description 2781-2786
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Environmental Toxicology and Chemistry
First page 2781
Last page 2786