Regime shifts in shallow lakes explained by critical turbidity

Area of Science:

• Ecological modeling
• Aquatic ecology
• Water quality management

Background:

• Shallow lakes exhibit alternative stable states: clear, macrophyte-dominated or turbid, phytoplankton-dominated.
• Contemporary models often overlook critical turbidity, a key factor in regime shifts.
• A simple, mechanistic model integrating resource competition and critical turbidity is needed.

Purpose of the Study:

• To develop a novel, simple, and mechanistic graphical and mathematical model (GPLake-M) for alternative stable states in shallow lakes.
• To integrate Scheffer's critical turbidity theory with nutrient and light competition theory.
• To provide a foundational model for understanding and managing shallow lake ecosystems.

Main Methods:

• Combined critical turbidity theory with nutrient and light competition theory.
• Developed the GPLake-M model, a graphical and mathematical framework.
• Parameterized and tested GPLake-M using the process-based PCLake model and pattern-oriented strategies.

Main Results:

• GPLake-M successfully captures essential mechanisms leading to alternative stable states in shallow lakes.
• The model is mechanistically understandable and relatively simple.
• The study elucidates the relationship between light-limited submerged macrophytes and nutrient-limited phytoplankton.

Conclusions:

• GPLake-M advances the fundamental understanding of regime shifts in shallow lakes.
• The model serves as a starting point for further mechanistic and management-focused research.
• Critical turbidity and light/nutrient competition dynamics offer new avenues for aquatic ecological research and monitoring.