Study of biocomplexity in an aquatic ecosystem through ascendency

Area of Science:

• Ecology
• Systems Ecology
• Theoretical Ecology

Background:

• Ecosystem ascendancy quantifies growth (system throughflow) and development (network information).
• Ecosystems tend to increase in ascendancy during succession.
• Equilibrium in ecosystems can transition to chaos due to various factors.

Purpose of the Study:

• To model an aquatic ecosystem (phytoplankton, zooplankton, fish) to explore the relationship between organism size and system dynamics.
• To investigate how changes in zooplankton body size affect ecosystem states, including chaos.
• To test the hypothesis that high ecosystem ascendancy correlates with maximum biocomplexity at the edge of chaos.

Main Methods:

• Developed a model of an aquatic ecosystem with three trophic levels.
• Incorporated allometric principles relating zooplankton body size to growth rate and half-saturation constant.
• Simulated ecosystem behavior under varying zooplankton grazing rates and half-saturation constants, observing transitions from equilibrium to chaos.

Main Results:

• Decreasing zooplankton body size increased grazing rates and decreased half-saturation constants.
• The model demonstrated transitions through equilibrium, stable limit cycles, period doubling, and ultimately chaos.
• High levels of ecosystem ascendancy were observed at the edge of oscillation, preceding chaos.

Conclusions:

• Ecosystem ascendancy is a valuable metric for understanding ecosystem development and complexity.
• The study supports the hypothesis that maximum biocomplexity and coordinated behavior occur at high ascendancy levels near the onset of chaos.
• Allometric scaling plays a crucial role in driving ecosystem dynamics and stability transitions.