Resource quantity and quality differentially control stream invertebrate biodiversity across spatial scales

Area of Science:

• Freshwater ecology
• Biodiversity research
• Ecosystem science

Background:

• Resource quantity is a known driver of biodiversity across spatial scales.
• The role of resource quality in cross-scale biodiversity patterns remains underexplored.
• This study investigates periphyton chlorophyll a (quantity) and stoichiometry (quality) in relation to invertebrate richness.

Discussion:

• Local scale: Invertebrate richness peaked at intermediate chlorophyll a levels and showed weak negative relationships with periphyton C:P and N:P ratios.
• Regional scale: Invertebrate richness exhibited strong negative relationships with both chlorophyll a and periphyton C:P and N:P ratios.
• Divergent relationships suggest resource quantity is a stronger regional diversity limiter than resource quality, aligning with eutrophication effects.

Key Insights:

• Resource quantity (chlorophyll a) and quality (stoichiometry) play distinct roles in freshwater invertebrate biodiversity across local and regional scales.
• Regional-scale patterns indicate that high resource quantity, potentially from eutrophication, negatively impacts invertebrate richness more than resource quality.
• Autochthonous resource quantity appears to be a more significant factor limiting regional freshwater biodiversity than resource quality.

Outlook:

• Future research should further elucidate the mechanisms by which resource quantity and quality interact to influence biodiversity across diverse aquatic ecosystems.
• Understanding these cross-scale dynamics is critical for effective freshwater resource management and conservation strategies, particularly in the context of global change.
• This study provides a foundation for predicting how changes in nutrient loading and primary production may impact stream biodiversity at multiple spatial extents.