Stable isotopes in Ecology: a tool to integrate scales and complexity 2025/2026

Overview

Stable isotopes ratios are widely used in diverse ecological areas of research. This course provides an in-depth exploration of stable isotopes as a valuable tool in Ecology, using isotopic signatures to trace ecological processes and revealing insights into nutrient and water cycling, species interactions, and environmental conditions across diverse ecosystems and communities. Students will gain a comprehensive understanding of how stable isotopes—such as δ¹⁵N, δ¹³C, δ¹⁸O, and δ²H—are used to unravel complex interactions within ecosystems, from plant-soil dynamics to water use in plants and diet tracing.

Key topics include:

• Stable Isotope Basics: Introduction to stable isotopes, with a focus on δ¹⁵N, δ¹³C, δ¹⁸O, and δ²H.
• Plant-Soil Interactions: Understanding how isotopes inform us about nutrient cycling, and plant-plant and plant-soil relationships.
• Plant Water Sources Use: Exploring how isotopic signatures help determine water sources and use strategies in plants.
• Diet Tracing & Isotope Mixing Models: Using stable isotopes for food web analysis, diet reconstruction, and applying isotope mixing models to track nutrient sources.
• Isotopic Niches: Examining the ecological roles of species based on their isotopic signatures.
• Isoscapes: Investigating spatial variations in isotopic signatures across landscapes and their ecological implications.
• Isotopes applications: Exploring additional uses of stable isotopes in fields such as geographic origins, tracking animal migration and forensic science.

The course will include not only theoretical classes but also practical components such as field sampling, lab sample preparation, overview of analysis techniques and group work. Students will be able to learn from case studies and engage in data analysis, interpretation of results, and collaborative problem-solving, allowing them to apply their theoretical knowledge.

Objectives

• Understand the principles of Stable Isotopes: Gain a basic understanding of stable isotopes ratios like δ¹⁵N, δ¹³C, δ¹⁸O, and δ²H, and how they are used and applied to study ecological processes.
• Examine ecological interactions: Learn how isotopic signatures reveal plant-soil interactions, nutrient and water cycling, pollution patterns, water use strategies in plants, and animal food webs, enhancing our understanding of ecosystem dynamics.
• Apply isotope techniques in diet tracing and species interactions: Develop the ability to use stable isotopes for reconstructing diets, analyzing food webs, and applying isotope mixing models to track food sources.
• Develop practical skills in field and laboratory techniques: Participate in hands-on activities, including field sampling, lab sample preparation, and isotope analysis, while collaborating on group projects to apply theoretical knowledge to research questions.
• Enhance data analysis and interpretation: Build skills in data analysis and interpretation, enabling students to critically evaluate stable isotopes data and interpret isotopic results.

Methods

Isotope ratio mass spectrometry (IRMS); Field sampling and sample preparation in diverse matrices (plants, animals, soils); Applying isotope mixing models.

Participants must be present at 85% of the contact hours (meaning they can miss one half-day) and actively participate in all activities.

This course can give credits to PhD programmes at CIÊNCIAS or programmes with partnership from CIÊNCIAS and other institutions with 6h-7h of contact hours per ECT, as a function of specific requirements. For these students, in addition to the exercises done during the week, delivering a written report after the course is mandatory. For programmes with fewer hours of contact per ECT (6h/ECT, getting 6 ECTs from the course), students must do an additional assignment (summary report). If needed, 1 or 2 additional hours of contact may be added. Such report(s) are also advised for other students requesting accreditation of the course in their institutions.

Minimum requirements: Bachelor in Biology, Natural Science or related areas

Directed to: Teachers, researchers, 2nd and 3rd cycle students, laboratory technicians in the areas of environmental studies, ecology, health, ecosystem management, conservation.