Community-level effects of ivermectin and moxidectin from cattle dung: zooplankton as study case

Abstract

Context: Ivermectin (IVM) and moxidectin (MOX), are widely used internal and external antiparasitic drugs for livestock. They enter into the aquatic environment because the treated animals metabolise only a small percentage of the administered doses, and the rest is eliminated through the faeces posing a risk to aquatic organisms. Aims: This study aimed to evaluate the responses of zooplankton to environmentally relevant concentrations of IVM and MOX spiked in cattle dung in a short-term exposure. Methods: We compared the composition of the community, density, species richness, diversity and total biomass between treatments with parasiticides and controls. Key results: The presence of both antiparasitic drugs altered the zooplankton community structure, leading to a shift in species composition. Cladocerans were the most affected, with a drastic reduction in their density. Additionally, a decrease in the density of copepods and an increase in the density of rotifers were observed in the MOX treatments.Conclusions: Both drugs caused a simplification of the zooplankton community as species richness and diversity decreased. Overall, MOX was more toxic than IVM.Implications: Our results suggest that long-term consequences on ecosystem services could arise, which merits the development of control and livestock management tools for the protection of these environments.