The protection of habitat types is reflected in the survival of an individual species and of the ecosystem as a whole
Below the surface, you will find a wide variety of landscapes, all with their uniquely special features and functions. Classifying landscapes helps to assess and predict the state of the environment, as well as the environmental factors affecting it.
Lasse Kurvinen and Suvi Kiviluoto
Kurvinen works as Senior Coordinator at Metsähallitus Parks & Wildlife Finland, and Kiviluoto as Researcher at the Finnish Environment Institute SYKE
Although this is still a new approach in the oceans, in recent years major steps have been taken to develop both classification and evaluation systems for the entire Baltic Sea. It is important to remember that protecting a habitat type also ensures the survival of many species.
The importance of protecting habitat types has long been known
In 1992, the European Union Habitats Directive set out the objective of protecting both species and habitat types, also known as biotopes. Species are quite distinct as assessment units but what are habitat types? Before an assessment can be made of the threat to a habitat type beneath the surface, it must somehow be defined and delineated.
There are different ways to determine a biotope
There are several overlapping systems for the demarcation and assessment of habitat types. The EU Habitats Directive defines underwater biotopes primarily through their geological features. For example, attention is drawn to coastal lagoons, which are separated from the open sea by the underwater threshold at the lagoon’s mouth.
Lagoons differ from large shallow bays, which are often much more exposed to waves and thus more efficient in water exchange. In the open sea areas, the directive recognises other habitat types, among others, underwater reefs and sand banks.
Eelgrass forms underwater meadows on sandy bottoms.
In addition to the geological features defined in the Habitats Directive, endangered biotopes are also assessed based on their species composition.
All of the Baltic Sea biotopes were not defined until the HELCOM HUB classification
Before 2013, a system for delimiting underwater biotopes across the entire Baltic Sea did not exist until HELCOM published its HUB classification, i.e. the HELCOM Underwater Biotope and Habitat classification system.
In Finland, the new classification system was applied for the first time in 2018, based on a publication entitled, “Threatened Habitat Types in Finland 2018 - Red List of Habitats Results and Basis for Assessment”. This evaluation included a total of 46 defined underwater habitat types. Although the Finnish Nature Conservation Act does not currently recognise any submerged habitats, flads and gloe-lakes which result from land uplift are assessed as combinations of habitat types and are partially protected by the Water Act.
Understanding and protecting habitat types safeguards the entire ecosystem
The classification of habitat types is underpinned by the objective of understanding and protecting nature’s biodiversity and functionality. It is clear that although entire ecosystems are difficult to protect, at the other extreme, individual genes and genomes are already protected.
It is natural for species conservation to go hand in hand with the protection of species-defined habitat types, also known as biotopes. In this case, the other species within a habitat are also preserved along with those needing specific protection. By directly protecting the habitats of as many species as possible, one can try to safeguard the functioning of the entire ecosystem.
The concept of biotopes conveniently combines the conservation goals of both species and habitats. Habitat types are located within different habitats, depending on the individual species or species group that determines them. In addition to endangered habitat types, key habitat types that support a particularly extensive number of different species, are also important in terms of ecosystem functioning.
The living conditions of many species are made possible by key habitat types
Biotopes and the species they maintain provide a variety of ecosystem services. Key habitat types in the Baltic Sea include the algae and mussel communities of reefs, the seagrass meadows of the sandy seabed, as well as the vascular plant communities of shallow marine bays.
A dense Blue mussel community lives on a rocky sea bottom.
These habitat types create three-dimensional structures on otherwise flat and featureless surfaces. Thus, they make it possible for more species to survive in an area.
Many benefits arising from marine areas, such as fishing, depend on key habitat types. Keeping fishing waters clean and catch quotas at a sustainable level are not enough to conserve fish stocks. The areas suitable for both the breeding and rearing of different species of fish must also be protected.
Coastal reefs, particularly those in the Bothnian Sea, are particularly important spawning grounds for herring. Flounder, in turn, require clean sandy bottoms. Pike and perch spawn in shallow and sheltered marine bays. Even the turbid inner waters of the Archipelago Sea are necessary, as almost 90% of the entire coastal stock of pike-perch stock comes from such areas.
The information related to the use and modification of underwater nature is constantly increasing. By understanding the functioning of habitat types and protecting them regionally, we create a good basis for the sustainable use of a changing Baltic Sea.