Freshwater toxicity testing using rehydrated Philodina sp. (Rotifera) as test animals.

Area of Science:

• Environmental Toxicology
• Aquatic Toxicology
• Ecotoxicology

Background:

• Rotifers are valuable for rapid aquatic toxicity screening due to readily available diapausing embryos.
• Desiccation-tolerant rotifer species offer potential for non-culture toxicity assessment systems.
• Current methods often require complex culturing techniques, limiting accessibility.

Purpose of the Study:

• To describe a novel freshwater toxicity testing system using rehydrated desiccated bdelloid rotifers (genus Philodina).
• To establish and validate three toxicity endpoints: ingestion, mortality, and reproduction.
• To demonstrate the system's utility with common heavy metals.

Main Methods:

• Desiccated Philodina rotifers were rehydrated for toxicity testing.
• Three endpoints were assessed: a 1.5-hour ingestion assay, a 24-hour mortality assay, and a 5-day reproductive assay.
• A dried commercial food product was utilized for the reproductive test.

Main Results:

• Reproduction was generally the most sensitive endpoint for copper, lead, mercury, and cadmium, with EC50 values ranging from 0.12 to 0.60 mg/L.
• Ingestion assays showed high sensitivity, with EC50 values ranging from 0.13 to 6.26 mg/L.
• The system demonstrated flexibility and required minimal biological expertise.

Conclusions:

• The rehydration of desiccated bdelloid rotifers provides a practical and accessible method for aquatic toxicity testing.
• The Philodina toxicity test system, utilizing ingestion and reproduction endpoints, is effective for evaluating metal toxicity.
• This approach reduces the need for specialized culturing, broadening the application of rotifer-based ecotoxicology.