Diet-consumer interactions under variable stressor conditions as revealed by stable isotope studies of individual amino acids

This research aims to gain deeper insights into riverine food web dynamics under varying stressor conditions through stable isotope studies of individual amino acids (AAs), focusing on Glutamic Acid (Glu) and Phenylalanine (Phe). We employ Gas Chromatography-Isotope Ratio Mass Spectrometry (GC-IRMS) to analyze Carbon and Nitrogen isotopes in AAs. By studying the Carbon isotope signatures of Essential Amino Acids (EAA) from primary producers and using Nitrogen isotope signatures of Glu and Phe for trophic position estimation, we assess food web structures based on amino group metabolic pathways. Our research reveals species' niches and trophic links under multiple stressors, providing insights into ecosystem structures and functions during degradation and recovery. We expect to observe changes in δ15N and δ13C values of AAs, indicating food web simplification under stress conditions. The study takes place in the Emscher/Boye catchment, reflecting a recovery gradient from pollution and hydromorphological degradation. Understanding diet-consumer interactions and food web dynamics amid stressors is vital for effective riverine ecosystem conservation and management. Our findings contribute to comprehending the spatial-temporal dynamics, crucial for preserving river ecosystem health and functionality in the face of environmental challenges.