How does sublethal permethrin effect non-target aquatic organisms?

Area of Science:

• Ecotoxicology
• Environmental Science
• Aquatic Biology

Background:

• Permethrin, a synthetic pyrethroid pesticide, is widely used in agriculture.
• Its accumulation in aquatic ecosystems poses risks to non-target organisms.
• Narrow-clawed crayfish (Astacus leptodactylus) are important freshwater indicators.

Purpose of the Study:

• To determine the acute and sublethal effects of permethrin on narrow-clawed crayfish.
• To assess permethrin's impact on antioxidant enzyme levels and hemolymph biochemistry.
• To establish the ecotoxicological profile of permethrin in a key freshwater invertebrate.

Main Methods:

• Determined the 96-hour LC50 (lethal concentration for 50% of the population) of permethrin for Astacus leptodactylus.
• Exposed crayfish to a sublethal concentration (0.09 μg/L) for 48 and 96 hours.
• Analyzed hemolymph biochemistry, total hemocyte counts, and tissue malondialdehyde (MDA) levels.

Main Results:

• The 96-h LC50 was 0.903 μg/L, indicating high acute toxicity.
• Sublethal exposure increased hemocyte counts, hemolymph potassium, and chloride levels.
• Gills and muscle showed increased MDA, while hepatopancreas showed decreased MDA; gill hyperplasia and hepatopancreas degeneration were observed.

Conclusions:

• Permethrin exhibits extreme acute toxicity to narrow-clawed crayfish.
• Sublethal permethrin concentrations induce significant physiological and biochemical disturbances.
• These findings highlight the ecological risk of permethrin to freshwater ecosystems.