Data description

Trend lakes – long time series on water chemistry and biology

Last changed: 22 August 2024

The overall objectives of the monitoring programme Trend lakes is to provide a measure of the state of locally unaffected lakes in Sweden. Water chemistry and biology (fish, benthic fauna, zooplankton, phytoplankton, macrophytes) are analysed in 106 lakes.


  • Surface water is sampled for water chemistry analysis every spring, summer, autumn and winter.
  • Sampling of benthic fauna takes place in all lakes once a year.
  • Sampling of phytoplankton takes place in all lakes at least once a year.
  • Sample fishing takes place in 45 of the lakes, annually in 15 lakes and every six years in the remaining 30 lakes.
  • Macrophytes are sampled in all lakes at six-year intervals.

Ten of the lakes are analysed more intensively. They sample water chemistry monthly (during the ice-free season), phytoplankton and zooplankton four times a year, and fish annually.

The dataset contains data from over a hundred lakes. In some of the lakes, monitoring has been ongoing for over 40 years.

As the trend lakes are relatively unaffected by point source discharges, the monitoring programme helps to establish a reference network of conditions and diffuse impacts in small lakes across the country.

The results of the monitoring provide input to the EU Water Framework Directive and data to the European Environment Agency (EEA). The results are also used as reference values for assessing changes in more affected areas, and provide a basis for further development and evaluation of assessment criteria and environmental quality objectives. The lakes are also important in reporting under the Air Quality Convention and data from several of the lakes are reported to the international monitoring programme ICP-Waters.

Programmets långa tidsserier har särskilt stort värde för analyser av klimatförändringarnas effekter, samt för uppföljning av sjöars återhämtning från försurning.

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Contact

Richard K. Johnson

Metadata

Publisher Department of Aquatic Resources (SLU Aqua), Department of Aquatic Sciences and Assessment
Funding agency Swedish Agency for Marine and Water Management
Keywords lakes, water chemistry, fish, benthic fauna, phytoplankton, zooplankton, references, trend lakes, reference lakes, time series lakes, metals, nutrients, pH, acidification, eutrophication
Data citation

Data from SERS (fish in streams):

The Swedish Agency for Marine and Water Management is responsible for coordinating water-related environmental monitoring in Sweden. If you use data from the database for electrofishing in streams in your publication, you should state that this has been produced within the framework of coordinated Swedish environmental monitoring.

Sers, B. (Editor). 2013. Swedish Electrofishing RegiSter – SERS. Swedish University of Agricultural Sciences (SLU), Department of Aquatic Resources. http://www.slu.se/electrofishingdatabase. [yyyy-mm-dd]

For data from Miljödata-MVM (phytoplankton, benthic fauna, macrophytes and chemical and physical parameters):

Miljödata-MVM [yyyy]. Swedish University of Agricultural Sciences (SLU). National data host lakes and watercourses, and national data host agricultural land, https://miljodata.slu.se/mvm/ [yyyy-mm-dd or dd/mm/yyyy].
File format Benthic fauna, phytoplankton and water chemistry: CSV, XLSX. Fish: docx, xlsx, pptx, pdf, TIFF, MHTML, CSV, XML, atomsvc.
Language Swedish
Data access service REST, SOAP
Subject area
  • Biology
  • Environmental toxins and toxicology
  • Water chemistry and hydrology
Habitat type
  • Lakes and streams
Species group
  • Algae
  • Fish
  • Invertebrates
  • Vascular plants
  • Mosses
Swedish environmental objectives
  • Natural acidification only
  • Reduced climate impact
  • Zero eutrophication
  • Flourishing lakes and streams
Related datasets

NORS – database for survey test-fishing
Environmental data MVM
Cyclically low-intensity monitored lakes
Trend watercourses - long time series with water chemistry and biology