Biomass competition connects individual and community scaling patterns

Area of Science:

• Ecology
• Physiology
• Marine Biology

Background:

• Metabolism and growth exhibit sublinear scaling with body mass across species.
• Ecosystem production and biomass also show similar sublinear scaling, posing a theoretical paradox.
• Existing ecological theories struggle to reconcile these identical scaling patterns at different biological organization levels.

Purpose of the Study:

• To resolve the paradox of similar sublinear scaling in metabolism and ecosystem production.
• To connect individual-level physiological scaling with ecosystem-level biomass scaling.
• To investigate the role of competitive interactions in unifying these scaling patterns.

Main Methods:

• Utilized marine phytoplankton as a model system to bridge individual and ecosystem scales.
• Analyzed data across three orders of magnitude in body size and biomass.
• Investigated the impact of biomass-driven competitive interactions on metabolic rates.

Main Results:

• Competitive interactions dependent on biomass consistently slow metabolism across phytoplankton species of varying sizes.
• These biomass-driven metabolic effects override species-specific differences, making community composition irrelevant to respiration and production.
• Sublinear scaling of ecosystem production arises from this density-dependent metabolism, irrespective of equilibrium state or resource availability.

Conclusions:

• Established a direct link between individual physiological scaling and ecosystem production scaling.
• Demonstrated that metabolic density-dependence unifies growth patterns across different biological scales.
• Provided a unified explanation for similar scaling laws in physiology and ecology.