Difference between revisions of "Case study:Pearls in Peril LIFE+ GB Project - Afon Eden"

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Project summary

The Afon Eden is located in north Wales and is a relatively unmodified river, mainly upland in character, of approximately 10km length. The Afon Eden supports the largest population of pearl mussels in Wales. Farming and forestry have been and continue to be the main activities in the catchment. Pressures affecting the Afon Eden population include diffuse pollution from agriculture, forestry, and highway sources. NRW currently describe the Afon Eden as unfavourable.

Pearls in Peril has restored 2.4km of in-stream habitat including gravel seeding to create fish spawning habitat and the placement of boulders from historic bank protection to re-instate river bed substrate and create habitat for freshwater mussels. To address diffuse pollution from forestry activities, the project removed 2ha of conifer regeneration, blocked 12km of forestry drains, fenced 4.5km to prevent livestock access and constructed 11 settlement ponds. This work is restoring 54ha of the Brynteg forestry block to wet woodland and blanket bog and is reducing the levels of diffuse pollution entering the Afon Eden.

The project is currently working to replace two fords with bridges. The fords are heavily used by vehicles, are a source of silt and present a pollution risk to the Eden. Pearls in Peril is also working closely with project partners, North and Mid Wales Trunk Road Agency, to install drainage interceptors at strategic locations that will collect runoff from the A470 carriageway and thus improve water quality in the Eden.

Monitoring surveys and results

Extensive monitoring work has been completed and reported. The monitoring work includes sonde analysis, water quality spot sampling, redox, macroinvertebrates, diatoms, fish and freshwater pearl mussel survey.

Redox results show a clear trend towards improved dissolved oxygen content in the substrates adjacent to and downstream of the Brynteg forestry block, indicating conservation measures at this site are having immediate positive results. Glochidial surveys indicated that trout are the preferred host fish as part of the freshwater pearl mussel lifecycle. However, electro-fishing also indicated that trout were the least abundant fish in the Afon Eden. As such, conservation measures that improve the status of the trout population would also be beneficial for freshwater pearl mussel. The on-going monitoring on the Eden has helped to focus the conservation work the project has implemented.