Predator Persistence through Variability of Resource Productivity in Tritrophic Systems

Area of Science:

• Ecology
• Ecological modeling
• Food web dynamics

Background:

• Trophic structure and energy transfer are crucial for community stability.
• Primary productivity fluctuations challenge higher trophic levels, but variability effects are understudied beyond simple food chains.
• Understanding resource variability impacts is key to predicting ecosystem resilience.

Purpose of the Study:

• To investigate the impact of resource productivity variability on a three-level food chain (resource, consumer, predator).
• To model predator persistence and trophic transfer efficiency under fluctuating resource conditions.
• To incorporate size-structuring and body-size-dependent energetics into the model.

Main Methods:

• Development of a tritrophic model adhering to mass conservation.
• Inclusion of size-structured prey and size-specific predation.
• Simulation of varying resource productivity and analysis of resulting population dynamics and energy transfer.

Main Results:

• Resource variability can unexpectedly enhance predator persistence.
• Increased variability leads to starvation mortality in juvenile prey, reducing intraspecific competition.
• This reduced competition increases prey availability for predators within their preferred size range.

Conclusions:

• Environmental variability, particularly in resource productivity, can sustain species at higher trophic levels.
• The model demonstrates that realistic body-size-dependent functions are critical for understanding variability's effects.
• Findings suggest that ecological complexity and size-structuring mediate the impact of environmental fluctuations on food webs.