Finnish inventory programme for underwater marine diversity
Velmu surveys the biodiversity of the underwater marine environment
Aiming towards the sustainable use and protection of the Baltic Sea
Finland’s marine nature is exceptionally beautiful. While it may not boast as many species as can be found in the oceans, Finland’s tens of thousands of islands, skerries, straits, coves, lagoons, sandy beaches, underwater rocks and ridge formations create a particularly diverse habitat for plants and animals alike. You can find a wide array of
colourful species and diverse nature, provided you know where to look.
Marine biodiversity at risk
Biodiversity is the foundation for life on earth, and the sea is no exception. However, the balance of the marine ecosystem and its biodiversity are currently under threat. Eutrophication and harmful substances are putting pressure on the Baltic Sea, while the distribution of species is changing as a result of climate change. The natural state of the sea is subject to constant change due to the construction of ports and bridges, extraction of gravel and sand, dredging, and disposal of dredge spoils. Moreover, organisms are threatened by disturbances to their habitats, excessive fishing, oil and chemical accidents, invasive species, plastic litter and underwater noise.
To avoid damaging our valuable marine environment, we need to know what kind of life exists beneath the surface of the sea. The Finnish Inventory Programme for the Underwater Marine Environment, Velmu, collects data for precisely this purpose – to promote the protection and sustainable use of the sea.
Velmu produces valuable information on Finland’s marine nature
Since it started in 2004, Velmu has collected observations from more than 170,000 points, which has provided us with an overall picture of species and habitats in our marine areas. This information is available in the open Velmu Map Service, and the programme has produced a book, Meren aarteet (2017, in Finnish), that provides general information on Finland’s underwater marine nature.
The objectives of Velmu are
- to map underwater marine nature and explore the characteristics of marine nature with a particular emphasis on increasing knowledge about species
and habitats that are either endangered or whose status cannot be assessed properly due to deficient data, - to process the collected data so it can be used to support the conservation and sustainable use of nature,
- to explore the characteristics of marine nature in areas under human pressure; and
- to engage in international cooperation in mapping marine biodiversity across the Baltic Sea region.
How is underwater marine nature surveyed?
Velmu surveys the sea floor, its flora and fauna, and fish spawning and larval habitats. The geology of the sea floor is studied using echo sounding and sediment sampling. Algae, aquatic plants and benthic animals are mapped using video recordings, diving and sample collection. Fish breeding grounds are surveyed using various scoops, seine nets and samplers.
Remote sensing methods, such as aerial and satellite images, are used to identify ground types and algae and vegetation zones in shallow sea areas. Various semi-automatic devices, e.g. remote-controlled measuring devices, are also being tested for use in the future.
The surveys may also include measurements of different properties of the sea, such as the temperature, salinity and transparency of the water and, when necessary, samples may be taken to assess the chemical properties of the water and to identify the bottom substrate.
Biological survey methods
Underwater habitats are mapped using several methods. The drop video method 1) involves lowering a video camera on a cable close to the sea floor. Later, the video recording is used to assess the quality of the sea floor and identify the larger species in the habitat. The survey can also be conducted using an ROV, Remotely Operated Vehicle 2) whose movement can be controlled from a survey vessel. In the line diving method 3), a 100 m transect line is led from the shore to the sea, and a skilled research diver identifies and records all species while still underwater. At the same time, samples may be taken for subsequent identification. This method provides precise, reliable information on the presence of species in a given habitat.
Geological mapping methods
Marine geological surveys are mainly carried out using acoustic methods. The most common of these are 1) single beam echo sounding, 2) multibeam echo sounding, 3) side-scan sonar imaging and 4) seismic reflection. Video recordings of the seabed and sediment sampling may also be used. These methods provide a precise picture of the quality and depth of the seabed. The data is used to determine the environmental requirements of the species observed.
Methods for surveying fish breeding grounds
The locations of coastal fish spawning and larval habitats are surveyed using a variety of methods, depending on the fish species being studied and the habitat in which the survey is carried out. In near-shore areas with submerged vegetation, 1) a white plate and scoop are used to sample fish larvae. In other shallow shore areas, a seine net is used, while ichthyoplankton samplers are used in open waters.
Remote sensing
Remote sensing methods, such as aerial photography, satellite imagery and green beam laser scanners (LiDARs), can be used to identify the type of seabed in shallow sea areas and to locate different types of algae and vegetation zones. Small-scale helicopters, i.e. drones, are also used to survey flads (brackishwater lagoons), for instance. In good conditions, algae zones stand out clearly in shallow water.
From data collection to the creation of maps
A picture is worth more than a thousand words. With this in mind, Velmu produces a large number of maps to illustrate the occurrence of species, habitats and other special features of marine nature in Finland’s marine areas. The maps can be used as tools for conservation efforts and for planning the use of the marine environment.
However, these impressive-looking multicoloured maps can be a double-edged sword. The maps are reliable only if they are based on extensive and professionally collected field data and scientifically credible analyses. For this reason, Velmu invests in thorough surveys, extensive environmental data and the latest modelling methods.
How is the data on underwater nature used?
The information produced in the programme is available in the open Velmu Map Service. The programme has also produced a book, Meren aarteet (2017, in Finnish) and Havets skattkammare (2021, updated edition in Swedish) that provides general information on Finland’s underwater marine nature in layman's language.
The mapping data is used by authorities, research and educational institutions, civil society organisations and private citizens alike. Data can be used for a wide range of purposes, such as:
- developing the network of protected areas,
- planning the management and use of existing protected areas,
- assessing the conservation status of species and habitats,
- protecting threatened species and habitats,
- protecting fish breeding areas and fish populations,
- assessing the state of the sea,
- planning the sustainable use of marine areas,
- minimising the damage caused by oil and chemical accidents,
- mapping regional ecosystem services,
- detecting and anticipating the impacts of climate change.
Finland is committed to the protection of the marine environment and the sustainable use of marine nature through national and EU legislation and a number of international conventions, such as the UN Convention on Biological Diversity (CBD) and the Helsinki Convention. Velmu produces valuable data used in fulfilling these commitments.
Velmu data are used for a wide range of marine nature assessments and reports. Examples include the State of Finland's Marine Environment 2018 report, the national assessments of threatened species and habitat types and the EU Habitats Directive reporting.
Velmu data were also used for the extension of the marine Natura 2000 sites in the southern part of the Archipelago Sea and for the definition of the Ecologically or Biologically Significant Marine Areas (EBSAs) in the Baltic Sea under the UN Convention on Biological Diversity's (CBD). Velmu data also played a key role in identifying and describing Finland's Ecologically Significant Marine Underwater Areas (EMMAs) in 2019.
Wide-ranging cooperation
Velmu is led by the Ministry of the Environment and coordinated by the Finnish Environment Institute. Parks & Wildlife Finland, the Geological Survey of Finland and Natural Resources Institute Finland are primarily responsible for the fieldwork. Other partners include the Centres for Economic Development, Transport and the Environment in coastal areas and Åbo Akademi. Other universities, higher education institutions and consulting companies are also involved as necessary.
In addition to the Ministry of the Environment, Velmu’s steering group includes the Ministry of Defence, the Ministry of Finance, the Ministry of Agriculture and Forestry, the Ministry of Economic Affairs and Employment, the Finnish Transport Infrastructure Agency, the Navy Headquarters, the Border Guard and the National Board of Antiquities.
