Morphological diversity increases with decreasing resources along a zooplankton time series

Area of Science:

• Marine Ecology
• Biodiversity Research
• Plankton Ecology

Background:

• Biodiversity is crucial for ecosystem functions like production.
• Traditional diversity measures (taxonomic, genetic, functional) often overlook organism morphology.
• Morphological diversity, beyond body size, is rarely explicitly studied in marine zooplankton.

Purpose of the Study:

• To quantify seasonal and long-term morphological diversity of marine zooplankton.
• To investigate the relationship between morphological diversity and environmental factors.
• To explore the implications of morphological diversity for ecosystem functioning.

Main Methods:

• Quantitative imaging of over 800,000 marine zooplankton individuals.
• Extraction and summarization of 45 morphological features into four key traits: size, transparency, circularity, and shape complexity.
• Calculation of morphological diversity indices (richness, evenness, divergence) using functional diversity metrics.

Main Results:

• Morphological diversity increased significantly during periods of low nutritive resources and plankton concentrations.
• This relationship held true on both seasonal and long-term (12-year) scales.
• Long-term increases in morphological diversity were not solely explained by changes in taxonomic diversity.

Conclusions:

• Marine zooplankton exhibit increased morphological diversity under low-resource conditions, supporting theoretical ecological relationships.
• A shift towards specialization and increased morphological variance, including extreme forms, is suggested under low production.
• These findings have potential implications for understanding trophic structures and carbon flux in marine ecosystems.