Effects of ashes from wildfires on local and regional aquatic food web structure and functioning

• Grant number: 25/24878-2
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: March 01, 2026
• End date: February 28, 2027
• Field of knowledge: Biological Sciences - Ecology - Theoretical Ecology
• Principal Investigator: Gustavo Quevedo Romero
• Grantee: Rodolfo Mei Pelinson
• Supervisor: Eoin O'Gorman
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Institution abroad: University Of Essex, England
• Associated to the scholarship: 23/06228-5 - Nutrient enrichment and temperature increase as potential enhancers of priority effects: consequences for the structure of aquatic communities and the flow of energy and matter between aquatic and terrestrial ecosystems, BP.PD

Abstract

Ashes resulting from wildfires can reach aquatic environments through runoff after heavy rains, potentially altering these environments mainly through increasing nutrient (e.g. nitrate and phosphate) and contaminant concentration (e.g. metals and PAHs). These two non-mutually exclusive pathways of effect can have contrasting effects on local food web structure, energy flux, and food web similarity (i.e. similarity in the identity of nodes and links). Therefore, here we aim to experimentally understand if ash contamination by runoff can change the structure and energy flux of aquatic food webs, as well as their regional similarity. To do so we carried out a 6-month mesocosm experiment where we added ashes from a native tree, simulating the burning of native vegetation, and from sugarcane leaves, simulating the burning of the most common crop fields found in the state of São Paulo. Ashes were added in a schedule that simulates runoff after heavy rains in the beginning of the rainy season. We carried out monthly sampling of macroinvertebrates, zooplankton, and phytoplankton, recording their abundance and estimating individual body masses using allometric equations. During the proposed research visit, we will infer trophic links through a literature review on feeding interactions and the strength of these interactions using energy fluxes. These fluxes will be calculated according to estimated gains (i.e. energy acquired from lower trophic levels) and losses (energy lost through metabolism and consumption by higher trophic levels). Metabolism in each node of the food web will be estimated using data from respirometry bioassays performed in Brazil. Finally, we will build statistical models to test whether local food web metrics, energy flux, and food web similarity, measured as distances to treatment centroids in multivariate space, vary as a function of our treatments and across time. Therefore, this project has the potential to not only assess the effect of ashes on community structure, but also on the entire functioning of these ecosystems. (AU)