Concrete conservation actions
In-stream habitat restoration
Restoration by wood material is carried out by construction of wooden structures, current deflectors and underminers, which reduce bottom siltation, oxygenate the bottom substrate, clean the bottom and spawning areas, and thereby improve the condition of the riverbed.
Restoring rapids: The main problem, in the rivers to be restored, is the straightening and clearing of the river channel for timber floating, which has reduced the habitats of FPM and its host salmonids. Boulders that were removed during channelizing work will be put back into the river. This leads to a more diverse but also more stable bottom topography and water velocity profile, creating a mixed bottom substrate and generating microhabitats on the riverbed preferred by FPM. Deeper pools will be created and together with the larger boulders they provide hiding and feeding places for salmonids.
Restoring spawning beds is carried out by focusing as much as possible on improving existing spawning areas, from which the suitable spawning gravel has flushed away. The river bottom is fluffed and sifted to make the substrate suitable for salmonid spawning and FPM juveniles. Keeping the spawning beds clean and oxygenated is ensured with wooden current deflectors and underminers.
Re-watering original riverbed: Obstacle-closed side channels will be opened to restore the water flow to the habitat and areas that have not had water flows for decades. The old river basin is cleaned of vegetation before water is led into it. This will lead to increase in the wet area due to the widening of the river and reconnects the river with the floodplain.
Migration barriers and sediment pools
Constructing sediment settling pools (SSP): In Finland, large-scale ditching of forests and wetlands has caused extensive damage to the stream nature by filling them with fine sediment causing harm especially to salmonids by reducing the number of spawning sites, shelters and suitable winter areas in streams. SSPs are constructed with the help of wooden structures (deflectors, underminers) into a highly sedimentary riverbed to slow-flowing areas of the river, with the purpose of gathering fine material arriving from upstream especially in the spring flood. The SSPs are emptied every few years as they fill up.
Removing migration barriers will ensure the free passages of migrating and moving animals. FPM is dependent on brown trout and Atlantic salmon for their dispersal since those species are the host for the mussel鈥檚 larvae. A barrier for the fishes (e.g. artificial road crossings or dams) also becomes a barrier for the FPM. Removing obstacles will facilitate recolonisation of habitats.
Creation of FPM kindergartens
Experimental pilot sites, in different ways constructed habitats suitable for FPM juvenile growth in riverbed gravel, will be established. These areas are monitored for oxygen conditions, stability and possible settling of FPM juveniles during the project.
Water management of catchment area
Blocking ditches: The most significant restoration method in water management of catchment areas carried out in the project is filling in ditches and building peat dams to raise water table level to restore peatlands. The ditches will also be blocked with pipe dams to reduce erosion of ditches and sediment flow to the rivers.
Runoff-water treatments and creation of wetlands are our measures to reduce the big amounts of nutrients and solids from the catchment areas loading the rivers. Runoff-water treatments are useful in those forest areas where it is needed to reduce nutrients or solid away from the running water before it goes to the river. The runoff-water is filtered through the soil and vegetation, and the wetlands will be established by damming and with minor digging efforts. In addition to water protection, the wetlands also have a landscape and recreational significance. Wetlands are home to a wide variety of species from plants and insects to birds, so they are also important from a biodiversity perspective.
Buffer zones and liming
Making/widening of buffer zones: The load nutrient and solids load from the catchment area will be reduced also by making and widening buffer zones of the rivers and brooks. Buffer zones are important for water protection, but they also ensure the microclimate of the water body and other special features of the sit yielding also other benefits such as increased biodiversity.
Bank protection: In the catchment areas there are gutted ditches where the land is exposed and susceptible to erosion before the vegetation begins to grow on them. Vegetation formation will be accelerated by planting, scalping, or sowing the riverbanks. In scalping, vegetation clumps are transferred from the intact sites to the gutted sites. The sowed species should be a fast-growing, a fast-rooted and a low-growing species.
Structure liming: The aim this measure is to improve the condition of clay soils and thus plant nutrient intake, reducing leaching of phosphorus from fields into water bodies. Structural liming improves the crumb structure and water permeability of clay soil in the long run and the pH of the soil rises closer to the level optimal for FPM and salmonids. The action is carried out in areas selected based on soil samples.
Breeding of FPM
Captive breeding of FPM will be carried out in two breeding stations and in the field: Konnevesi Research Station of JYU in Central Finland and P玫lula fish farm in Estonia, and in River 脜by盲lven in Sweden. Either glochidia or adult mussels of 9 endangered FPM populations are brought to the breeding stations, released glochidia used for infecting fish (the parasitic stage of the FPM life cycle on salmonid gills), and released juveniles maintained in the breeding station until they are ready to be reintroduced to their home rivers - first either in hole plates or gravel boxes and later in bottom gravel. The reintroduction of artificially bred juveniles will increase the population density of FPM to a level which will revive the functional life cycle of the mussel and will thus prevent extinction and give time for other project actions to restore the adequate recruitment of the FPM.
