Spatial drivers of instability in marine size-spectrum ecosystems

Area of Science:

• Ecology
• Theoretical Ecology
• Mathematical Biology

Background:

• Size-spectrum models describe marine ecosystem dynamics from plankton to fish.
• These models currently lack spatial components to explain community structure.

Purpose of the Study:

• To extend size-spectrum models with spatial dynamics.
• To investigate if internal ecosystem dynamics can generate spatial irregularities and patterns.

Main Methods:

• Incorporated spatial dynamics into size-spectrum models, including random motion and 'fitness-taxis' (directed movement towards higher fitness).
• Utilized Fourier analysis and numerical experiments for pattern-formation analysis across diverse ecosystems.
• Examined the interplay between diffusion (stabilizing) and fitness-taxis (destabilizing) effects.

Main Results:

• Diffusion stabilizes ecosystem equilibrium, while fitness-taxis destabilizes it, creating traveling, non-stationary, spatially inhomogeneous population densities.
• A significant asymmetry exists where stabilizing diffusion effects dominate over destabilizing fitness-taxis effects.
• Fitness-taxis can drive pattern formation and spatial heterogeneity even in uniform environments.

Conclusions:

• Fitness-taxis is a potential mechanism for generating spatial heterogeneity in diverse marine ecosystems.
• The study highlights the importance of spatial dynamics in understanding ecosystem structure and pattern formation.
• Extended size-spectrum models provide a framework for exploring ecosystem-level spatial dynamics.