The EU Habitats Directive protects certain aquatic plants

The EU Habitats Directive includes four aquatic plant species found along the Finnish coastline. The directive obliges Finland to protect these species and their habitats.

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The EU Habitats Directive covers approximately 1,300 plant and animal species or subspecies found within the EU territory. These selected species are listed in the annexes of the directive and are referred to as species of Community interest. Member States are required to maintain or achieve a favourable conservation status for these species.

The EU Habitats Directive includes just under 20 species found in Finland’s marine areas. Four of these are aquatic plants. According to the 2025 assessment, all four species have an unfavorable conservation status in Finland. This means that their protection needs to be strengthened.

Water lobelia threatened by eutrophication

Water lobelia grows in low-salinity brackish water and is found in the northern Baltic Sea, along the coasts of Finland and Sweden. Typical habitats include openings in reed and sedge vegetation or small pools on grazed coastal meadows.

This sturdy plant, which rises above the water surface, could previously be found along all coastal areas of Finland, although its occurrences were sparse. Since then, it has disappeared from the Gulf of Finland and declined sharply in the Bothnian Sea. The largest new populations are found around the islands of the Bothnian Bay, where land uplift creates new bare growth substrates.

The decline of water lobelia is likely due to eutrophication in the Baltic Sea and the cessation of coastal grazing. Reed beds are taking over the habitats suitable for the species.

Observations of Mair’s tail in Finnish coastal areas starting from 1980. The map is based on observations recorded in Laji.fi portal that have a coordinate accuracy of 100 meters.

The majority of known occurrences of Baltic water-plantain are in Finland

Baltic water-plantain is a species endemic to the Baltic Sea region, with its distribution mainly concentrated along the eastern coast of the Bothnian Bay, from Kalajoki to Tornio. This delicate plant lives fully submerged underwater, as its name suggests. It grows in sheltered locations at depths of less than half a meter and requires slightly brackish water around it.

The distribution area of water-plantain has significantly decreased since the 1950s. Its habitats are degraded by dredging and coastal construction, but most notably by eutrophication and the resulting spread of reed beds. Silting of the seabed also poses a threat.

Finland has a special responsibility for the preservation of water-plantain, as populations along the Finnish coast account for up to 80 percent of the entire European population. Slightly more than half of the Finnish occurrences are protected.

Observations of Baltic water-plantain in Finnish coastal areas starting from 1980. The map is based on observations recorded in Laji.fi portal that have a coordinate accuracy of 100 meters.

Finland is responsible for protecting Najas tenuissima

Najas tenuissima occurs in only about twenty lakes in Finland and in a few low-salinity river estuaries along the southern coast. The species is extremely rare globally, which highlights the importance of its Finnish populations. Finland thus has a special responsibility to protect this internationally rare species.

However, N. tenuissima has declined in Finland. Over the past decades, it has lost at least half of its previously known habitats.

N. tenuissima is a small and delicate submerged plant. As a weak competitor, it cannot tolerate overgrowth in its habitat and loses space to stronger species. In addition to eutrophication, the species suffers from dredging, shoreline construction, and the influx of humus and suspended solids from the catchment area.

Observations of Najas tenuissima in Finnish coastal areas starting from 1980. The map is based on observations recorded in Laji.fi portal that have a coordinate accuracy of 100 meters.

Persicaria foliosa needs open muddy shores

Persicaria foliosa occurs in Finland both in inland waters and along the coast. It grows in shallow water or on wet ground, often on muddy shores in floodplains and river estuaries. The largest and most abundant populations are found in the river estuaries along the coast of the Bothnian Bay.

P. foliosa benefits from grazing, which keeps stronger competitors in check. The cessation of coastal grazing and the eutrophication of coastal waters have accelerated the overgrowth of P. foliosa habitats and contributed to the species’ decline.

P. foliosa also suffers from changes in water flow conditions that prevent the accumulation of mud. Small-scale digging along the shore can even benefit the species by exposing new growth substrate. However, dredging and shoreline construction usually degrade the growing conditions for P. foliosa.

Observations of Najas tenuissima in Finnish coastal areas starting from 1980. The map is based on observations recorded in Laji.fi portal that have a coordinate accuracy of 100 meters.

Lue seuraavaksi

Benthic animals live on both hard and soft bottoms