Multigenerational Exposure to Mancozeb Impacts Fitness Traits and Population Dynamics in Ceriodaphnia cornuta...

The seepage of agrochemicals into surface water and groundwater from treated fields poses a serious threat to freshwater ecosystems. The frequently used fungicide Mancozeb degrades in water into a metabolite, Ethylene thiourea (ETU), which is more persistent and often more toxic, with the potential to impact non-target zooplankton. This study evaluates the acute and chronic responses of abundant cladoceran zooplankton Ceriodaphnia cornuta Sars, 1885, through acute and chronic bioassays spanning six generations of continuous exposure. The susceptibility of C. cornuta neonates from the sixth generation was compared to that of neonates with no prior exposure, using an acute bioassay. Our results showed that Mancozeb contamination negatively affected the survival and reproduction of C. cornuta, and the effect was concentration-specific. Notably, exposure to 1.54 μg/L Mancozeb across six generations resulted in a significantly longer life expectancy at birth and higher reproductive rates. In contrast, the sixth-generation neonates (continuously exposed) had a lower 48 h LC₅₀ for Mancozeb compared to naive organisms (no prior exposure). These findings suggest that continuous exposure of C. cornuta to environmental concentrations of Mancozeb across generations leads to increased sensitivity to Mancozeb in the offspring. This highlights the need for further research on the impacts and evolutionary consequences of commercial formulations on non-target crustaceans.