Assessing the effects of chemical mixtures on high levels of biological organization: an experimental and a modelling approach

• Grant number: 25/23897-3
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: January 30, 2026
• End date: January 29, 2027
• Field of knowledge: Biological Sciences - Ecology - Applied Ecology
• Principal Investigator: Evaldo Luiz Gaeta Espindola
• Grantee: Diego Ferreira Gomes
• Supervisor: Andreu Rico
• Host Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Institution abroad: Universitat de València, Spain
• Associated to the scholarship: 24/08039-8 - Ecotoxicological effects of microplastics and pesticides, isolated and in mixture, on the native species Chironomus sancticaroli (Diptera) in freshwater aquatic ecosystems, BP.PD

Abstract

Chemical pollution is a global threat to aquatic biodiversity. Retrospective chemical risk assessments are based on aquatic toxicity data for single-test species, and thus lack a comprehensive assessment of chemical impacts on high levels of biological organization (i.e., populations, communities). Although micro/mesocosm studies provide a relevant tool to assess chemical effects on populations and communities (for individual chemicals and mixtures), their use for retrospective risk assessments remains limited. This project aims to advance our understanding of the impacts of contaminant mixtures in aquatic ecosystems by utilizing knowledge generated from new and existing micro- and mesocosm experiments, and by testing the accuracy of the PERPEST model (an AI-based model fed with micro and mesocosm data) to make accurate predictions regarding contaminant mixture effects. A mesocosm experiment will be conducted in 1 m³ mesocosms (located in the Albufera Natural Park, Valencia, Spain) contaminated with azoxystrobin and copper (individually and in mixture). The following evaluation endpoints will be monitored in the experiment: physicochemical parameters, and phytoplankton, zooplankton, and macroinvertebrate communities. The results of the experiment will be used to experimentally demonstrate and to understand the mechanisms causing additive or non-additive (i.e. synergistic, antagonistic) effects at higher levels of biological organization (population, community). Furthermore, this study will be complemented by a literature review and meta-analysis to describe the extent to which (non)additive effects of binary pesticide mixtures have been observed in aquatic populations and communities tested in microcosm and mesocosm experiments and to study the prevalence of such responses across groups of species and contaminant levels. Finally, the outcomes of this literature review will be used to test the accuracy of the AI algorithms and mixture toxicity models integrated into the PERPEST model, which can be used to assess the risks caused by contaminant mixtures measured in aquatic ecosystems worldwide. (AU)