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Related Experiment Video

Updated: May 6, 2026

Modeling the Size Spectrum for Macroinvertebrates and Fishes in Stream Ecosystems

Modeling the Size Spectrum for Macroinvertebrates and Fishes in Stream Ecosystems

Published on: July 30, 2019

Understanding patterns and processes in models of trophic cascades.

Michael R Heath¹, Douglas C Speirs, John H Steele

¹Department of Mathematics and Statistics, University of Strathclyde, Livingstone Tower, Glasgow, G1 1XP, UK.

Ecology Letters

|October 30, 2013

Summary

Density dependence in consumer uptake or mortality is crucial for realistic trophic cascades in food webs. This applies to both top-down and bottom-up cascades, impacting ecosystem dynamics and management strategies.

Keywords:

Bottom-up density dependence food chain food web harvesting model predator-prey simulation top-down

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Last Updated: May 6, 2026

Modeling the Size Spectrum for Macroinvertebrates and Fishes in Stream Ecosystems

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Published on: July 30, 2019

Linking Predation Risk, Herbivore Physiological Stress and Microbial Decomposition of Plant Litter

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Published on: March 12, 2013

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Area of Science:

Ecology
Ecosystem Dynamics
Food Web Theory

Background:

Global changes in nutrient enrichment and apex predator declines are altering ecosystems.
Trophic cascades significantly impact food webs, with varying strengths across ecosystems.
Existing food chain models do not fully explain the variability in cascade strength.

Purpose of the Study:

To investigate the necessary conditions for generating realistic trophic cascades in food web models.
To determine the role of model formulation, specifically density dependence, in reproducing observed cascade effects.
To test the applicability of findings from simple food chains to more complex marine food web models.

Main Methods:

Development and analysis of simple food chain models incorporating density-dependent regulation.
Mathematical modeling of consumer uptake and mortality rates.
Application of conclusions to a complex marine food web model with varying nutrient inputs and harvesting rates.

Main Results:

Inclusion of density-dependent regulation is essential for realistic top-down cascades.
Realistic bottom-up cascades require density dependence, particularly mortality regulation (e.g., disease, intraguild predation).
These findings hold true for both simple food chains and complex marine food web models.

Conclusions:

Density dependence is a key factor in the strength and realism of trophic cascades.
Model formulation significantly influences the accurate representation of ecosystem dynamics.
Understanding these mechanisms is vital for predicting and managing ecosystem responses to environmental change.