A novel method for preventing surface film entrapment of water fleas and its application for toxicity testing with heavy metals.

Some water fleas such as Daphnia galeata and Bosmina longirostris are difficult to culture and use in ecotoxicity testing since they can easily become entrapped at the surface film. Cetyl alcohol was the most prevalent chemical used to prevent the entrapment of water fleas in previous studies. However, cetyl alcohol possesses a number of disadvantages including its toxicity and water insolubility. This study presents a novel method for preventing surface film entrapment of the water flea D. galeata and B. longirostris acute testing. We examined the applicability of saponin extracts from Quillaja saponaria, natural surfactants commonly extracted from plants. Its application of saponin extracts was tested by ecotoxicity testing of heavy metals. Based on the acute test results for heavy metals, a concentration of 1.0 mg/L of saponins was determined as suitable for preventing surface film entrapment of D. galeata and B. longirostris with negligible adverse effects. This study proposes a novel method for preventing surface film entrapment of D. galeata and B. longirostris through the application saponins and could be valuable to make them suitable test species in ecotoxicity testing.