Development and application of a sediment toxicity test using the benthic cladoceran Chydorus sphaericus

Area of Science:

• Environmental Toxicology
• Aquatic Ecology
• Ecotoxicology

Background:

• Pelagic daphnids are commonly used in aquatic toxicity testing.
• There is a need for alternative test organisms, particularly benthic species, for sediment toxicity assessments.
• Chydorus sphaericus is a benthic cladoceran with potential for use in toxicity testing.

Purpose of the Study:

• To develop and validate a whole sediment toxicity test using the benthic cladoceran Chydorus sphaericus.
• To evaluate C. sphaericus as an alternative to pelagic daphnids in sediment toxicity testing.
• To assess the sensitivity of C. sphaericus to common aquatic toxicants in both aqueous and sediment matrices.

Main Methods:

• Established and optimized a laboratory culture of Chydorus sphaericus.
• Determined dose-response relationships for cadmium, copper, and ammonia in aqueous exposures.
• Applied the developed test to assess toxicity of field-collected contaminated sediments.

Main Results:

• Chydorus sphaericus exhibited sensitivity to cadmium, copper, and ammonia comparable to daphnids (96 h LC50 values provided).
• A significant negative correlation was observed between C. sphaericus survival and toxicant concentrations in contaminated sediments.
• The test demonstrated effectiveness in detecting toxicity in real-world sediment samples.

Conclusions:

• The developed whole sediment toxicity test using Chydorus sphaericus is suitable for routine laboratory use.
• C. sphaericus serves as a viable alternative to pelagic daphnids for sediment toxicity assessments.
• This method provides a valuable tool for evaluating the ecological risk of contaminated sediments.