Functional redundancy modifies species-area relationship for freshwater phytoplankton

Area of Science:

• Ecology
• Limnology
• Microbial Ecology

Background:

• Species-area relationships (SARs) are fundamental ecological patterns.
• Aquatic and microbial systems are underrepresented in SAR research.
• Understanding SARs in diverse aquatic environments is crucial.

Purpose of the Study:

• To investigate the algal species-area relationship (SAR) in various freshwater bodies.
• To analyze how phytoplankton species richness and functional richness vary with lake area.
• To identify mechanisms driving SAR patterns in aquatic microbial communities.

Main Methods:

• Studied lakes, pools, and ponds across a wide size range (10⁻²–10⁸ m²).
• Utilized species-specific and functional group data for phytoplankton analysis.
• Compared area dependence of species richness and functional richness.

Main Results:

• A right-skewed, hump-shaped relationship was observed between area and phytoplankton species richness.
• Functional richness did not exhibit this hump-shaped pattern, indicating functional redundancy.
• The Small Island Effect was observed, and a 'large lake effect' was identified, reducing pelagic species richness in large lakes due to wind-induced mixing.

Conclusions:

• Functional redundancy is key to the unusual hump-backed SAR in phytoplankton.
• Mechanisms regulating microbial and macroscopic community richness share similarities but differ in importance across scales.
• Aquatic SARs reveal unique patterns like the 'large lake effect' driven by physical forces.