A catchment scale evaluation of multiple stressor effects in headwater streams

J. J. Rasmussen, Ursula S. McKnight, Maria Christina Loinaz, Nanna Isbak Thomsen, Mikael Emil Olsson, Poul Løgstrup Bjerg, Philip John Binning, B. Kronvang

Research output: Contribution to journalJournal articleResearchpeer-review

372 Downloads (Pure)

Abstract

Mitigation activities to improve water quality and quantity in streams as well as stream management and restoration efforts are conducted in the European Union aiming to improve the chemical, physical and ecological status of streams. Headwater streams are often characterised by impairment of hydromorphological, chemical, and ecological conditions due to multiple anthropogenic impacts. However, they are generally disregarded as water bodies for mitigation activities in the European Water Framework Directive despite their importance for supporting a higher ecological quality in higher order streams.

We studied 11 headwater streams in the Hove catchment in the Copenhagen region. All sites had substantial physical habitat and water quality impairments due to anthropogenic influence (intensive agriculture, urban settlements, contaminated sites and low base-flow due to water abstraction activities in the catchment). We aimed to identify the dominating anthropogenic stressors at the catchmentscale causing ecological impairment of benthic macroinvertebrate communities and provide a rank-order of importance that could help in prioritising mitigation activities. We identified numerous chemical and hydromorphological impacts of which several were probably causing major ecological impairments, but we were unable to provide a robust rank-ordering of importance suggesting that targeted mitigation efforts on single anthropogenic stressors in the catchment are unlikely to have substantial effects on the ecological quality in these streams.

The SPEcies At Risk (SPEAR) index explained most of the variability in the macroinvertebrate community structure, and notably, SPEAR index scores were often very low (< 10% SPEAR abundance). An extensive re-sampling ofa subset of the streams provided evidence that especially insecticides were probably essential contributors to the overall ecological impairment of these streams.

Our results suggest that headwater streams should be considered in future management and mitigation plans. Catchment-based management is necessary because several anthropogenic stressors exceeded problematic thresholds, suggesting that more holistic approaches should be preferred.
Original languageEnglish
JournalScience of the Total Environment
Volume442
Pages (from-to)420-431
ISSN0048-9697
DOIs
Publication statusPublished - 2013

Fingerprint Dive into the research topics of 'A catchment scale evaluation of multiple stressor effects in headwater streams'. Together they form a unique fingerprint.

Cite this