How are fish food web metrics influenced by the loss of lateral and longitudinal connectivity in Amazonian streams?

• Grant number: 25/14938-8
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• Start date: October 01, 2025
• End date: March 31, 2026
• Field of knowledge: Biological Sciences - Ecology - Applied Ecology
• Principal Investigator: Lilian Casatti
• Grantee: Yullia Kaory Shimizu Alves
• Supervisor: Cecilia Gontijo Leal
• Host Institution: Instituto de Biociências, Letras e Ciências Exatas (IBILCE). Universidade Estadual Paulista (UNESP). Campus de São José do Rio Preto. São José do Rio Preto , SP, Brazil
• Institution abroad: Lancaster University, England
• Associated to the scholarship: 25/03918-6 - Are the trophic structure and trophic web metrics of ichthyofauna explained by the environmental conditions of Amazonian streams?, BP.MS

Abstract

The ecological integrity of streams is dependent on hydrological connectivity, which is primarily associated with riparian vegetation in the lateral dimension and with water flow in the longitudinal dimension. Land-use change disrupts both lateral and longitudinal connectivity, affecting stream ecological dynamics, particularly fish feeding, which highlights fish food webs as a consistent approach, yet still overlooked, for assessing stream conservation. Amazonian streams (igarapés) have a sensitive ichthyofauna and are impacted by human activities, which demand studies that describe how these assemblages respond to connectivity loss. In this context, the project objective is to evaluate how fish assemblage food web metrics respond to the igarapés hydrological connectivity loss. To this end, fish and local environmental variables were sampled (used to calculate habitat integrity index-HII), and data on road crossings and forest landscape will be collected for 28 streams under different conservation conditions, 15 located inside Jamanxim National Park (protected area under full protection), and 13 around the park. Using previously stomach content analysis and trophic guild classifications, food web metrics (nestedness, modularity, connectance, specialization, centrality, and robustness) will be calculated. These metrics will be related to connectivity in the lateral dimension (forest landscape and HII) and longitudinal dimension (density and distance of road crossings) through Generalized Additive Models (GAMs). It is expected that the results of this project will contribute to revealing the conservation status of Amazon streams, supporting management plans within the protected area.