Predation, competition, and nutrient recycling: a stoichiometric approach with multiple nutrients

Area of Science:

• Ecology
• Theoretical Ecology
• Aquatic Ecosystems

Background:

• Ecological models often simplify nutrient dynamics and interspecies competition.
• Understanding nutrient limitation and predator-prey interactions is crucial for ecosystem stability.
• Previous models typically focus on single limiting nutrients or simpler food webs.

Purpose of the Study:

• To develop and analyze a multi-nutrient, multi-species model of competition and predation.
• To investigate the effects of nutrient supply ratios (N:P), carbon availability, and predator preference on ecological outcomes.
• To explore the interplay between resource competition, apparent competition, and nutrient recycling.

Main Methods:

• Formulation of a mathematical model incorporating two prey species and one predator with three essential nutrients (C, N, P).
• Parameterization of the model using a flagellate-preying-on-bacteria system.
• Numerical simulations to explore long-term dynamics across various nutrient supply ratios and predator preferences.

Main Results:

• Species coexistence and competitive exclusion were observed, contingent on nutrient supply and predator preference.
• Apparent competition, mediated by the predator, and resource competition for nutrients were key drivers of outcomes.
• Nutrient recycling by the predator significantly influenced effective nutrient supply.
• Complex dynamics like multiple attractors and limit cycles occurred in limited parameter spaces, with nutrient constraints limiting their amplitude.

Conclusions:

• Multi-nutrient dynamics and predator-mediated interactions critically shape ecological community structure.
• Predator behavior (preference) and nutrient recycling can override simple competitive exclusion principles.
• Complex ecological dynamics are constrained by multiple essential nutrient limitations.