A new meta-analysis of 159 studies and 350 experimental observations offers key insights on the impact of chemical pollution on freshwater ecosystem functions
Freshwater ecosystems perform vital functions like breaking down organic matter, cycling nutrients, and producing oxygen. But how reliably can we predict the impact of chemical pollution on these functions?
We analysed how pesticides, pharmaceuticals, and metals affect five core ecosystem functions under controlled conditions: respiration, decomposition, nutrient cycling, photosynthesis, and primary production.
Key takeaways
- Decomposition (with detritivores) and photosynthesis showed clear, monotonic declines as chemical concentrations increased—matching patterns seen in field studies.
- Microbial-only decomposition and primary production, however, showed no consistent trends, reflecting greater variability in response.
- A regulatory disconnect: Current ecological quality targets often don’t align with actual ecosystem-level impacts, suggesting that existing risk assessments may not adequately protect functional integrity.
The study emphasises the potential to use existing data to build generalizable links between chemical stress and ecosystem function. But it also highlights the need for:
- Broader chemical coverage,
- Consideration of environmental context, and
- Validation in field or semi-field settings.
The bottom line: Ecosystem functions can show predictable declines with chemical exposure, but current regulatory approaches need updating to reflect this reality—and to truly protect the services ecosystems provide.
The paper “Meta‑analysis on the effects of chemical stressors on freshwater ecosystem functions” by Alexander Feckler, Ralf Schulz, and Ralf B. Schäfer was published on 6 July 2025 in Environmental Sciences Europe
Feckler, A., Schulz, R., Schäfer R.B. (2025): Meta‑analysis on the effects of chemical stressors on freshwater ecosystem functions. Environmental Sciences Euopre, DOI: 10.1186/s12302-025-01167-w