Freshwater Pearl Mussel and its habitats (LIFE04/NAT/SE/00023)
Freshwater Pearl Mussel and its habitats (LIFE04/NAT/SE/00023)
Key features of the case study
Drivers
Main concerns: Ecological concerns
Legal requirements: Natura 2000
Opportunities: Broader management plan (Swedish national conservation plan)
95 % of the Fresh Pearl water mussel population in Central Europe has fallen. The specie is classified by IUCN as endangered and is included in the EU habitat directive. Sweden is home to a large part of the remaining population (a core area) and therefore have an international responsibility for the species’ long-term survival’.
Pressures
Hydrological regime modification
Artificial barries upstream from the site
Artificial barries downstream from the site
Alteration of instream habitats
Sedimentation and sediment input
Nutrients pollution
Micropollutants
Acidification
Humans activities
Mainly forestry
Agriculture
Global objectives
Species enhancement and habitats improvement were the main objectives of the project by developing and testing methods to achieve a favourable conservation status for the freshwater pearl mussel (Margaritifera margaritifera) in Sweden. However, freshwater mussel was not the only target specie of the project. A freshwater mussel population decrease highlights a deterioration of the environnment, the improvement of freshwater mussels habitats will thus benefit other aquatic species such as host fish.
Specific goals (process oriented)
In order to achieve the conservation of Margaritifera margaritifera, the project aimed to :
1. eliminate the migration obstacles to host fish along ten watercourses
2. improve the river bed in eight watercourses
3. manage the banks along two small rivers
4. Re-introduce young mussels (test in one stream)
Site description
Measures selection
Description
Several measures were implemented aiming to restore the Margaritifera margaritifera population using different means:
1. Water flow quantity improvement
Repairing a dam that regulates the water flow into the stream Lillsjöbäcken to avoid water shortage in summer
2. Sediment flow quantity improvement
Blocking of 17 ditches with wood and ground materials to reduce negative impact from siltation
3. Longitudinal connectivity improvement
Removing obstacles
Fixing incorrectly placed road culverts
Building bypasses around migration obstacles
4. In-channel structure and substrate improvement
Deposit of gravel and small stones in fast-flowing river sections (restoration of around 1300 m2 of stream grounds across eight sites through )
5. Riparian zone improvement
Removal of spruce and other vegetation which impact on streams, in favour of deciduous trees along two shoreline sites (a total of 4.5 hectares buffer zone have been thinned and cleared along the streams Sollumsån and Bratteforsån)
6. Specie enhancement
Reintroduction of freshwater pearl mussels (1 000 mussels collected from a nearby watercourse in the same basin.)
Constraints
Every measures were not implemented as foreseen due to different constraints. Some actions were actually compromised due to historic cultural values, and one action was postponed due to disagreement with landowner. Furthermore, the planned deposit of gravel was less than anticipated due to research which revealed lower need.
Success criteria
The mussel recruitment is expected within the coming 10–20 years. None measurable criteria were actually set in the frame of the LIFE project due its too short time frame. However, measurable criteria with regards to the Margaritifera margaritifera recruitment have been set in the frame of the swedish national conservation plan (XX).
Ecological response
Other biota
Due to the complex life cycle of the freshwater mussel, it will take 5-10 years (at least) before it is possible to assess the real conservation impact of the implemented actions. However, the first monitoring highlights an increase of freshwater pearl mussel larvae on the fish geals.
Hydromorphological response
Monitoring before and after implementation of the project
Before
Biotic, chemistry and hydromorphologic studies were carried before restoration in order to select suitable sites by evaluating the viability and the size of the population:
1. BOTIC: Monitoring freshwater pearl mussel and host fish. Electricfishing were carried to evaluate the host fish population (and to assess mussel larvae parasites on fish geals) and mussels inventories were done by using an Aquascope or peep box (monitoring according to the standard method recommended by the Swedish Environmental Protection Agency)
2. HYDROMORPHOLOGIC: Monitoring riverbed substrates by documenting the rate of sedimentation of riverbeds, the distribution of substrate size from silt to boulder, the turbidity of the water and the level of sedimentation (June-September)
3. WATER QUALITY (especially pH)
After
Those assessments were also carried after restoration. The post-monitoring, carried on by the County Administrative Board, still runs for the Margaritifera margaritifera population and also electric fishing. Besides, the University of Karlstad is currently monitoring the sedimentation of the river beds. Sedimentation samples were taken before and after the restoration to see whether the siltation/sedimentation has decreased. This monitoring aims to evaluate the success and efficiency of the restoration and of land use change (bad forestry management is a common source to sedimentation).
Reference site
Socio-economic aspects
Contact person within the organization
Name : Sofi Alexanderson
Role : Project manager/coordinator
OrganisationName : WWF Sweden
OrganisationType : NGO-Foundation
Phone-Number : 0046 6247449
Email : sofi.alexanderson@wwf.se
==Extra background information== OTHERS FEEDBACKS/ LEARNINGS
Inputs of LIFE/INTERREG
LIFE helped the project managers to implement a broad range of measures by making a large amount of money quickly available but also by giving access to a large network (contacts with other LIFE Nature projects). On the other hand, the LIFE bureaucracy led to a heavy administrative part,
Project improvements
Limits faced
The timeframe of the project (5 years) is way too short to evaluate specie enhancement measures. It will take at least 10 years before knowing whether the restoration was a success or a failure.
Others lessons
The importance of gathering all the actors/stakholders of the catchment area and create an interaction with them. (agreement and dialog with the landowners for example) The importance of information and education of actors within landuse (mainly foresty) Remember to document and save all photos and monitoring information The importance of develop a detailed action plan
Follow-Up
The Margatifera margatifera conservation continues through the national swedish conservation plan (especially the monitoring part). The LIFE project was actually the starting point of this national plan and therefore added lots of technical, and scientific inputs in this broader management plan.
Restoration of freshwater pearl mussel Streams (Degerman et al., 2009): http://www.wwf.se/source.php/1257735/Restoration%20of%20FPM%20streams.pdf)
National conservation plan : http://www.naturvardsverket.se/Documents/publikationer/620-5429-5.pdf (swedish)
References
Website : www.wwf.se/fpm
Reports :
LIFE Layman’s report : http://www.wwf.se/source.php/1268431/Freshwater_pearl_mussel.pdf
LIFE Progress Report http://www.wwf.se/source.php/1164065/Progress%20report%202007%20LIFE04NATSE000231.pdf
Related Measures
- Remove barrier
- Narrow water courses
- Improve/Create water storage
- Reduce undesired sediment input
- Install fish pass/bypass/side channel for upstream migration
- Modify culverts, syphons, piped streams
- Develop riparian forest
