Watercourse biology

From a biological perspective, the state of Swiss watercourses is good, but at varying degrees. Problems exist particularly in the intensively used Central Plateau, where bodies of water are structurally impaired and fish are unable to migrate in many areas. The damage caused by certain agriculture-related substances is putting pressure on small bodies of water in particular; the biology of medium-sized bodies of water is being adversely affected by micro-pollutants from wastewater treatment plants.

A FOEN-commissioned nationwide analysis of all recorded data on macrozoobenthos in small watercourses (cantonal monitoring sites and Biodiversity Switzerland) shows that many of these bodies of water are in a substandard biological state. Around half of the 709 samples taken at 406 sites did not meet the requirements of the Waters Protection Ordinance.

The greatest problems can be found in low-lying bodies of water between 301 and 400 metres above sea level, where over 70% of biotic communities of marine invertebrates have substandard ecological conditions, which can be attributed to pesticide pollution, among other causes.

In total, approximately 50% of macrozoobenthos samples show pesticide pollution. An analysis of land use in the catchment area of the small watercourses studied makes it clear that there are huge deficiencies in intensively used settlement and agricultural areas.

Different results for surface water quality

The preliminary results of biological studies from the start-up phase of the National Surface Water Quality Monitoring Network (NAWA, see below) paint a different picture. Nearly 90% of the stations met the DI-CH diatom index quality goals and thus reflect decent conditions as concerns nutrient pollution in watercourses.

However, the evaluation of macrozoobenthos with the IBCH Index was not quite as positive: Macrozoobenthos at nearly two-thirds of the 88 stations evaluated were found to be in a good to very good state. The evaluation of macrophytes produced a similar result (approximately 60% of the stations were in a good to very good state, where watercourses had plenty of vegetation). Due to non-material pressures such as morphology and water flow, the situation for macrophytes is worse than it is for diatoms.

Biological studies of fish at NAWA monitoring sites in the trout and greyling region of the Central Plateau show that only about one-third of the fished areas are in a very good or good ecological state. Around two-thirds of these areas are in an acceptable or good state, while about 10% are in an unsatisfactory state. Some of the reasons for this are deficiencies in watercourse morphology and water quality, insufficient water flow or extreme flow fluctuations, as well as obstructions in watercourses.

Zustand der Schweizer Fliessgewässer

This publication does not exist in English. It is available in other languages. 2016

National monitoring and evaluations of state

In addition to standard chemical and physical tests, biological studies of aquatic plants, diatoms, macroinvertebrates and fish provide information about the chemical, morphological and hydrological state of watercourses. These are all good indicators for evaluating the state of bodies of water. The investigative methods used for these indicators are developed within the modular stepwise procedure under the direction of the FOEN and Eawag and applied in cantonal and national monitoring programmes.

Through the National Surface Water Quality Monitoring Network (NAWA), the FOEN is working with cantons on creating the bases for documenting and evaluating the state of and changes in Swiss bodies of water on a national level.

Coordinated biological studies in the High Rhine area

Since the early 1990s, coordinated biological studies have been carried out in the High Rhine area by neighbouring countries and cantons. The available data, which have been collected over a long period of time, provide valuable indications of long-term changes in biological state. Among other things, they show that invasive species migrate in the Rhine River.

Further information

Documents

NAWA: Messstellendokumentation (PDF, 112 MB, 15.05.2018)Chaix O., Stalder P., Hürlimann J. 2018: Biologische Erhebungen der Nationalen Beobachtung Oberflächengewässerqualität (NAWA), Messstellendokumentation (Startphase 2012–2013) im Auftrag des BAFU

Fish

Streckendossiers Fische 2015 (PDF, 35 MB, 15.05.2018)Beschreibung der Befischungsstrecken im Auftrag des BAFU

NAWA-Fachbericht Modul Fische 2015 (PDF, 3 MB, 04.04.2019)Spalinger L., Dönni W. und Guthruf J. 2017: Biologische Erhebungen der Nationalen Beobachtung Oberflächengewässerqualität (NAWA), Modul Fische 2015. Expertenbericht im Auftrag des BAFU

NAWA-Fachbericht Modul Fische 2012-2013 (PDF, 5 MB, 16.05.2014)Dönni W. und Guthruf J. 2014: Biologische Erhebungen der Nationalen Beobachtung Oberflächengewässerqualität (NAWA), Modul Fische (Startphase 2012–2013). Expertenbericht im Auftrag des BAFU

NAWA-Modul Fische 2012-2013 Quantitative Erhebungen (PDF, 567 kB, 23.06.2014)Dönni W., Guthruf J., Riedl C., Werner S. und Zaugg C. 2014: Biologische Erhebungen der Nationalen Beobachtung Oberflächengewässerqualität (NAWA), Modul Fische: Quantitative Erhebungen (Startphase 2012–2013). Auswertungen im Auftrag des BAFU

NAWA-Modul Fische 2012-2013 Streckendossiers Fische (PDF, 77 MB, 16.05.2014)Beschreibung der Befischungsstrecken im Auftrag des BAFU

NAWA-Modul Fische 2011-2013: Karten - Besatzkoordination Fische (PDF, 29 MB, 23.06.2014)Dönni W., Guthruf J., Riedl C., Werner S. und Zaugg C. 2014: NAWA TREND Biologie 2011-2013, Karten Besatzkoordination Fische im Auftrag des BAFU

Macrozoobenthos

NAWA-Fachbericht Modul Makrozoobenthos 2015 (PDF, 1 MB, 28.02.2017)Stucki P. und Knispel S. 2017: Biologische Erhebungen der Nationalen Beobachtung Oberflächengewässerqualität (NAWA), Modul Makrozoobenthos 2015. Expertenbericht im Auftrag des BAFU

NAWA: Rapport technique Macrozoobenthos 2011-2014 (PDF, 1 MB, 31.05.2015)Stucki P., Knispel S., Vicentini H. et Wagner A. 2015: NAWA TREND Biologie. Rapport Sectoriel Macrozoobenthos, campagne 2012, campagnes complémentaires 2011‐2014. Sur mandat de l’OFEV

Diatoms

NAWA-Fachbericht Modul Diatomeen 2015 (PDF, 1 MB, 12.07.2017)Hürlimann J. und Straub F. 2017: Biologische Erhebungen der Nationalen Beobachtung Oberflächengewässerqualität (NAWA), Modul Diatomeen und äusserer Aspekt 2015. Expertenbericht im Auftrag des BAFU

NAWA-Fachbericht Modul Diatomeen 2011-2013 (PDF, 3 MB, 23.06.2014)Hürlimann J. und Straub F. 2014: NAWA TREND Biologie 2011-2013, Teil Diatomeen. Expertenbericht im Auftrag des BAFU

NAWA: Äusserer Aspekt (PDF, 566 kB, 15.05.2018)Hürlimann J., Küng M., Straub F. 2014: NAWA TREND Biologie 2011-2013, Teil Äusserer Aspekt. Erfassung der Feldprotokolle und erste Analysen. Kurzbericht im Auftrag des Bundesamtes für Umwelt

Macrophytes

NAWA-Fachbericht Modul Makrophyten 2015: Anhänge A-E (PDF, 1 MB, 13.09.2019)Roth E. und Müller N. 2017: Biologische Erhebungen der Nationalen Beobachtung Oberflächengewässerqualität (NAWA), Modul Makrophyten 2015: Anhang. Expertenbericht im Auftrag des BAFU

NAWA-Fachbericht Modul Makrophyten 2015: Anhang F (PDF, 208 MB, 13.09.2019)Roth E. und Müller N. 2017: Biologische Erhebungen der Nationalen Beobachtung Oberflächengewässerqualität (NAWA), Modul Makrophyten 2015: Anhang. Expertenbericht im Auftrag des BAFU

NAWA-Fachbericht Modul Makrophyten 2012 (PDF, 958 kB, 16.05.2014)Roth E. 2013: NAWA TREND Biologie
Teilbereich Makrophyten 2012. Expertenbericht im Auftrag des BAFU

NAWA-Fachbericht Modul Makrophyten 2012: Anhang F (PDF, 34 MB, 16.05.2014)Roth E. 2013: NAWA TREND Biologie
Teilbereich Makrophyten 2012: Messstellendossiers im Auftrag des BAFU

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