Understanding temporal variability across trophic levels and spatial scales in freshwater ecosystems

Area of Science:

• Ecology
• Ecosystem Dynamics
• Community Ecology

Background:

• Temporal variability in ecological processes typically decreases with increasing spatial and organizational scales.
• Understanding variability across trophic levels and its mechanisms is crucial for ecological stability.
• Metacommunity dynamics, encompassing populations across trophic levels, require further investigation into variability patterns.

Purpose of the Study:

• To analyze temporal variability in abundance across spatial scales and trophic levels in freshwater metacommunities.
• To identify mechanisms driving temporal variability and synchrony across different ecological scales and trophic positions.
• To assess the influence of environmental and spatial factors on ecological stability.

Main Methods:

• Analysis of abundance time series from 355 freshwater sites across three continents.
• Hierarchical partitioning to disentangle variability propagation across scales and trophic levels.
• Structural equation modeling to link temporal variability, synchrony, biodiversity, and environmental/spatial factors.

Main Results:

• Temporal variability in abundance decreased from producers to tertiary consumers, primarily at the local scale.
• Population synchrony increased with trophic level locally, while among-community synchrony decreased regionally.
• Predators appeared to stabilize metacommunities by buffering bottom-up variability, with stronger stabilizing effects at higher trophic levels.

Conclusions:

• Trophic structure, particularly the role of mobile predators, is key to metacommunity stability.
• Ecological stability is an emergent property influenced by food web complexity and scale.
• Biodiversity loss and habitat fragmentation pose complex threats to ecosystem temporal stability.