In 2003, Cumbria Wildlife Trust and the Freshwater Biological Association set up the Cumbria Tarns Project. Its aim was to engage trained local volunteers in re-surveying tarns that had been surveyed 30 years previously by Ralph Stokoe. Repeating these surveys has provided us with two sets of data that can be compared and analysed to assess whether species composition and tarn ecology has changed over the last 30 years, and help determine the possible causes of this change.

As the project has developed its remit has widened to include surveys of UK Biodiversity Action Plan (UKBAP) and Cumbria Biodiversity Action Plan (CBAP) habitats and species, particularly nutrient poor (oligotrophic) tarns and the scarce aquatic fern, pillwort (Pilularia globularia). We have also undertaken fish surveys and in 2008 carried out an aquatic plant survey of Windermere.

The Tarns Project is the widest ranging survey of aquatic plants in small water bodies in Cumbria since Ralph Stokoe’s in the 1970’s. In total we have collected data for 370 tarns, including many that have not been previously studied in detail, thereby adding to the knowledge of the distribution of aquatic plant species, including some rarer species such as pillwort. We have collected information on a range of other biological and environmental data such as management and surrounding landscape.

An initial analysis of data has suggested a decline in species richness, particularly among the submerged and floating macrophyte species. The analysis also showed a shift in nutrient status in the lowland tarns towards more eutrophic conditions. In the upland tarns there was no detected change in ecology, however species richness has declined.

This information provides an invaluable resource, which can be used to further protect tarns, particularly through appropriate management. The owners of tarns have been sent details of the survey and organisations involved in scientific, conservation and environmental protection work can access the information using a geographical mapping system and the Tarns and Ponds database.

A conference was held in February 2009, detailing the project and its findings. Copies of these talks can be downloaded here.

The full Cumbria Tarns Report, presented at the conference, can be download here.

Funding for the Cumbria Tarns Project expired early in February 2009. We are currently undertaking a detailed review of the data collected during the last 6 years with a view to identifying future work and funding streams.