Multiple stressor effects on biodiversity and ecosystem functioning in a Mediterranean temporary river

Area of Science:

• Ecology
• Hydrology
• Environmental Science

Background:

• Temporary rivers are vital ecosystems providing essential goods and services.
• These ecosystems and their biodiversity are vulnerable to climate change and human pressures.
• The combined effects of flow intermittency and pollution on temporary river biodiversity and ecosystem functioning remain understudied.

Purpose of the Study:

• To investigate how multiple stressors, specifically flow intermittency and pollution, affect biodiversity and ecosystem functioning in a Mediterranean temporary river.
• To analyze the biodiversity-ecosystem functioning (B-EF) relationships under these multiple stressors.
• To understand the mechanisms driving B-EF relationships in temporary rivers.

Main Methods:

• Assessed benthic community diversity (diatoms and macroinvertebrates).
• Measured ecosystem processes: resource use efficiency (RUE) and organic matter breakdown (OMB).
• Examined these factors along gradients of pollution and flow intermittency.

Main Results:

• Macroinvertebrate diversity decreased with increased stress, while diatom diversity showed an opposite trend.
• Both pollution and flow intermittency negatively impacted ecosystem functioning (RUE and OMB).
• Biodiversity-ecosystem functioning relationships varied: RUE decreased with diatom diversity, OMB increased with macroinvertebrate diversity.

Conclusions:

• Flow intermittency and pollution act as significant stressors in temporary rivers, altering biodiversity and ecosystem functioning.
• Distinct mechanisms (selection vs. complementarity) appear to drive biodiversity-ecosystem functioning relationships for diatoms and macroinvertebrates.
• Findings highlight the risks to temporary river ecosystems under global change and inform conservation strategies.