Case study:Nursery habitat for the freshwater pearl mussel in Haukåsvassdraget
Project overview
Status | Complete |
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Project web site | |
Themes | Habitat and biodiversity, Hydromorphology, Land use management - agriculture, Monitoring, Social benefits, Spatial planning, Water quality, Urban |
Country | Norway |
Main contact forename | Ole |
Main contact surname | Rugeldal Sandven |
Main contact user ID | |
Contact organisation | Bergen municipality |
Contact organisation web site | http://www.bergen.kommune.no |
Partner organisations | University of Bergen (UiB), Norwegian Environment Agency, Rådgivende Biologer AS, Entrepreneur Magne Løvaas AS |
Parent multi-site project | |
This is a parent project encompassing the following projects |
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Project summary
The Haukås watercourse (Haukåsvassdraget) is located in the northern part of Bergen municipality. The catchment is just under 9 km2 and the length is about 6 km. There are large flood variations. The remnant population of the freshwater pearl mussel can be documented back to the 17th century by court records. Bergen municipality purchased a large wetland area, Haukåsmyrene in the early 1900s. Agriculture developed throughout the river area and resulted in the lowering of water levels, cultivation, canalization and drainage. Then came a period of strong urbanization and development. The mussels were thought to be extinct until 2002. At that point a few hundred old mussels were found - a typical sign that the water environment is too poor for recruitment. The water quality and possible inprovement measures were quickly identified during a close cooperation between the public management and the academic community.
Comprehensive mapping of both diffuse and point source emissions were conducted and requests where sent in order to stop or reduce pollution. Two important challenges had to be solved to save the mussel population: a) the mussels had to be helped with recruitment, b) the condition of the river had to be improved.
A nursery habitat for the freshwater pearl mussel was built in a side stream following a Czech concept. Based on experience, such nursery habitats create good growing conditions for both mussels and trout. When the mussels grow larger, they can release and settle in favorable locations in the main river. It should be mentioned that the Haukås marshes (Haukåsmyrane), which are central to the watercourse, have already been designated as a priority restoration area for wetlands.
Monitoring surveys and results
There are continuous improvements in breeding and cultivation of freshwater pearl mussels. The pioneering work of the University of Bergen's facility at Austevoll is a success that provides hope for both the mussels in Haukås and other endangered populations. Batches of mussels have been released back into the river with promising results. It is still too early to know for sure how the mussel habitat will work over time. The biological and water chemistry changes are being monitored.
Unfortunately, there has been recorded episodes of pollution of the river that have led to mussel death in recent years. For instance, in 2017 (Johnsen, G.H, S. Kålås & I. Wathne 2018. Status for elvemusling i Haukåsvassdraget 2017. Radgivende Biologer AS, rapport 2629, 34 sider, ISBN 978-82-8308-485-6.)
Litterature e.g.: https://www.radgivende-biologer.no/wp-content/uploads/2019/06/2629.pdf
Lessons learnt
The situation in the small urban Haukåsvassdraget is unclear. It will take time to achieve safe and stable good ecological conditions. Breeding and cultivation of freshwater pearl mussels is already a success. In order to succeed in returning mussels to the main river, water conditions must be improved. Supporting nursery habitats could supplement the conservation work. The mussel habitat at Haukås is an important trial project.
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Catchment and subcatchment
Site
Project background
Cost for project phases
Reasons for river restoration
Measures
MonitoringHydromorphological quality elements
Biological quality elements
Physico-chemical quality elements
Any other monitoring, e.g. social, economic
Monitoring documents
Additional documents and videos
Additional links and references
Supplementary InformationEdit Supplementary Information
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