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State of the environment

State of the Baltic Sea is still concerning

The Baltic Sea is affected by eutrophication, certain harmful substances, and the increasing use of marine areas. Some of Finland's marine areas show signs of improvement.
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Surface of the sea.
© Ilkka Lastumäki / Syke.

The Baltic Sea, surrounded by dense population, is sensitive to changes. The problems of the sea extend to the entire marine area, including Finnish waters. Finland is also responsible for the pollution of the sea, especially the poor condition of its coastal waters. However, not all Finland's marine areas are in poor condition; in some parts, the state of the sea is good.

The state of the Baltic Sea is constantly monitored. The Baltic Sea monitoring programme observes eutrophication, water quality, marine nature, and other aspects of the sea's well-being. Based on the results, an assessment is made of the state of each aspect. The goal is to achieve a good state in each area. There is still work to be done throughout the entire Baltic Sea.

Current

Eutrophication affects most the southern and southwestern coasts of Finland

The eutrophication of the Baltic Sea is evident in cyanobacterial blooms, water turbidity, and oxygen depletion in the seabed. In Finland, the situation is most critical in the coastal waters of the Gulf of Finland and the Archipelago Sea. Among the open sea areas, the Gulf of Finland and its western marine areas are in the poorest condition. There have been slight signs of improvement along the Gulf of Finland coastline. The Archipelago Sea has, however, experienced an increased presence of cyanobacteria in recent years.

One indicator of eutrophication is the concentration of a-chlorophyll, or chlorophyll-a, which reflects the amount of phytoplankton in the water.

The abbreviations used in the graph describing the eutrophication status of coastal waters are:
Ss Gulf of Finland inner archipelago
Su Gulf of Finland outer archipelago
Ls Southwest inner archipelago
Lv Southwest intermediate archipelago
Lu Southwest outer archipelago
Ses Inner coastal waters of the Bothnian Sea
Seu Outer coastal waters of the Bothnian Sea
Ms Kvarken inner archipelago
Mu Kvarken outer archipelago
Ps Inner coastal waters of the Bothnian Bay
Pu Outer coastal waters of the Bothnian Bay

Nutrient levels have decreased, but not yet enough

Eutrophication is caused by high levels of nutrients - nitrogen and phosphorus - in seawater.  Nutrient concentrations in the Baltic Sea peaked in the 1980s and 1990s. Since then, they have stabilized or decreased, but not yet enough. Finland is particularly concerned about the Archipelago Sea, where nutrient pollution is one of the Baltic Marine Environment Protection Commission's (HELCOM) hot spots - one of the sea's worst problems.

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The maps depict the amount of phosphate and dissolved nitrogen in the northern Baltic Sea.
Nutrient concentrations in the northern Baltic Sea, in the open-sea surface layer. © Finnish Environment Institute.

Harmful substances persist for a long time

Environmentally hazardous substances were most prevalent in the Baltic Sea during the 1960s to 1980s. Since then, the use of the most dangerous substances has been banned and their concentrations in the sea have decreased. Certain flame retardants are now of greatest concern. Oil concentrations in seawater have fallen as oil spills have become less frequent. The wide range of potential pollutants and their persistence cast a shadow over future developments.

Awareness of marine litter

Marine litter has accumulated in Finland's seas over the decades. Most of this litter is plastic. Some of the marine litter drifts onto shores or settles on the seabed, while some breaks down into small microplastics. Visible debris is most abundant on the shores of the Gulf of Finland, the Archipelago Sea, and the Bothnian Sea; in some areas, littering seems to be decreasing. Monitoring of micro litter in water and sediment has started in the 2020s. Restrictions on plastic use are expected to reduce marine litter.

Underwater noise disturbs marine life

Underwater noise is most intense in shipping lanes but extends far beyond them. In about fifth of the Gulf of Finland's surface area, underwater noise exceeds the threshold of 20 decibels. Dredging, underwater explosions, and sonar surveys cause momentary spikes in noise. Underwater noise is not audible to the human ear, but it can significantly disturb marine life, potentially causing harm or even death. Assessing the underwater noise situation is only at an early stage, as is mitigation.

Marine environment is both thriving and struggling

The state of marine nature is particularly affected by eutrophication, but also by invasive species, dredging and coastal development. The seabed and the marine food web are the weakest in the Gulf of Finland, with no signs of improvement. Among breeding seabirds, bottom-feeding divers fare the worst, while grazing birds have thrived. Seal populations have mostly increased. Many migratory fish species are endangered.

Invasive alien species pose a risk

Around 220 alien species have arrived in the Baltic Sea - animals and plants that humans have either deliberately or accidentally brought here from waters around the world. Approximately 30 of these species are present in the coastal waters of Finland. Not all invasive species are harmful, but some displace native species or weaken their communities. The Invasive Alien Species Act aims to prevent the harm and risks caused by invasive species.

The Baltic Sea Action Plan improves the state of the sea

The European Union's goal is to achieve good status for all marine areas. In the Baltic Sea, this objective is pursued in cooperation with the Baltic Marine Environment Protection Commission (HELCOM). A crucial instrument in this effort is the Baltic Sea Action Plan (2007). It has delivered many improvements, but has not yet prevented deterioration of the sea. The programme was intensified in 2021 and the EU and HELCOM have agreed to protect at least 30% of the sea area by 2030.

The Finnish marine management plan includes concrete actions

Finland's marine management is guided by a national marine management plan. Concrete actions are set out in the plan's programme of measures, which runs until 2027 and aims to ensure that Finland's entire marine area is in good condition. This goal is supported by a water protection enhancement program, which seeks, among other things, to reduce nutrient emissions from agriculture and alleviate the pollution of the Archipelago Sea.

Futher reading

Publisher

Finnish Environment Institute (Syke)

Discover more

MarineFinland.fi
Finnish marine data portal consolidating information about the Baltic Sea from key institutions of administrative branches producing marine data in Finland.
Go to marinefinland.fi
Baltic Marine Environment Protection Commission HELCOM
Commission is an intergovernmental organisation (IGO) and a regional sea convention in the Baltic Sea area.
Go to helcom.fi