Do stable isotopes reflect the food web development in regenerating ecosystems?

Area of Science:

• Ecology
• Biogeochemistry
• Environmental Science

Background:

• Monitoring food web complexity and biodiversity is crucial for understanding ecosystem regeneration.
• Stable isotopes, specifically delta15N and delta13C, offer potential insights into trophic dynamics.

Purpose of the Study:

• To evaluate the efficacy of delta15N and delta13C values in monitoring food web development.
• To investigate the influence of dietary quality and animal stress on isotopic signatures.
• To assess the impact of faeces recycling and starvation on stable isotope measurements.

Main Methods:

• A model food chain was established using woodlice (Porcellio dilatatus) fed on a fungus (Chaetomium globosum).
• Two diets with varying C:N ratios and delta15N values were used to induce different levels of dietary stress.
• Elemental and isotopic composition of woodlice, faeces, exuviae, and remaining food were analyzed after 7 weeks.

Main Results:

• Observed increases in delta15N values of woodlice relative to diet varied between treatments (5.7% vs. 2.5%).
• Observed delta13C shifts showed a reverse relationship (1.0% vs. 1.6%) and correlated positively with starvation.
• Faeces recycling was identified as a key factor explaining unexpected 15N-enrichments.

Conclusions:

• Stable isotopes (delta15N and delta13C) are valuable tools for elucidating trophic interactions in regenerating ecosystems.
• Accounting for starvation and faeces recycling is essential for accurate interpretation of isotopic data.
• This study demonstrates the utility of stable isotopes in assessing ecosystem recovery and complexity.