Baltic Sea ecosystem wheel presents eleven key descriptors making up a healthy Baltic marine ecosystem

News 2015-09-04 at 10:17

Finnish Environment Institute (SYKE) has recently updated information on the state of the Finnish Baltic Sea ecosystem. The publication, Sea Spray 2015 (Meren pärskäys 2015 in Finnish) presents scientific information in rich visual form. The publication provides e.g. the ecosystem wheel showing the 11 key Marine Strategy Framework Directive (MSFD) descriptors and their state, evaluated during the initial 2012 State of the Baltic Sea Assessment as a part of the Finnish marine resources management plan. Despite significant protection measures during the past decades, the Baltic Sea ecosystem remains in critical condition.

Sea Spray 2015
Baltic Sea ecosystem wheel presents the 11 key descriptors making up Good Environmental Status (GES).

State of the Baltic Sea monitoring methods are constantly developing

Baltic Sea ecosystem conditions have been observed for over a hundred years, providing a useful base for state of the sea assessment. While the Baltic Marine Environment Protection Commission (HELCOM) has already committed over forty years of valuable work to improve the state of the sea conditions, long-term monitoring needs to continue. Efforts require ongoing development and updating of observations to keep state of sea indicators valid and applicable.

The EU Marine Strategy Framework Directive introduced in 2008 the elements of litter and noise to its list of Baltic Sea research topics. Researchers at SYKE have conducted tests to investigate the drift of micro plastics in a food web. According to Researcher Outi Setälä, the studies indicate that many planktonic organisms are unable to distinguish litter from their natural food. Another study on the Baltic Sea is the international BIAS project (Baltic Sea Information on the Acoustic Soundscape), launched in 2014, which investigates the underwater soundscape of the sea. “Once we gather more information, we will be able to schedule operations that cause noise at a time when they will cause the least amount of disturbance to organisms,” emphasises Senior Adviser Jukka Pajala from SYKE.

Eutrophication, hazardous substances, and climate change key challenges

Many factors make the Baltic Sea susceptible to the effects of eutrophication and hazardous substances, but the susceptibility of different marine areas to eutrophication varies. The agriculture-dominated catchment area of the Finnish Archipelago Sea has few lakes and it only absorbs about one percentage of the phosphorus released into the water systems. “Most of the nutrient loading in the Baltic Sea originates from fields, as they are rich in nutrients, they are tilled often and cultivation is centred around coastal areas with few lakes,” clarifies Senior Research Scientist Petri Ekholm from SYKE.

Blue mussels
© Raisa Turja

The impact of hazardous substances on organisms in the Baltic Sea has been investigated with the help of i.a. blue mussels.

Hazardous chemicals that enter the sea originate from various sources. The environmental impacts of many everyday chemicals are still poorly understood. The combined impact of chemicals of human origin and nature’s own chemicals is difficult to predict. More severe changes in the ecosystem can be prevented more easily if their effects are monitored at the organism level.

Eutrophication causes anoxia at the sea floor. Even short-term anoxia has an impact on the diversity of benthic communities, and the benthic communities of the Gulf of Finland nowadays primarily comprise species that tolerate low-oxygen conditions. Large benthic specimens are an important food source for birds and fish. An indicator for the size distribution of long-lived species is currently under development. When completed, it will provide information on the state of benthic communities as well as the functionality of the food web.

The species composition of the phytoplankton in the Baltic Sea has changed over the long term, and the number of blue-green algal blooms has increased. Additionally, eutrophication has reduced the size of zooplankton species, which degrades the quality of food for fish that eat plankton. Eutrophication has also changed benthic communities in shallow waters: annual coastal filamentous algae are among the winners of the battle, while bladder wracks belong to the losing side. The protection of different natural habitats is often the best way to also retain the species living in these environments, but not even protected areas can stop the impacts of eutrophication.

Climate change may also exacerbate eutrophication in the Baltic Sea. “This is due to the nutrient runoff to the Baltic Sea that is caused by milder winters and increased rainfall. However, the speed and strength of the impacts are difficult to predict at this stage,” states Research Professor Markku Viitasalo from SYKE.

Healthy sea is in everyone’s interest

Changes in the Baltic Sea’s food web need to be examined as a whole. “Humans have disturbed the ecosystem of the Baltic Sea, in particular by increasing the amount of nutrients and consequently the amount of algae,” sums up Leading Researcher Harri Kuosa from SYKE, adding that “another clear change can be seen in the reduction in number of large animals in the upper level of the food web, which means increased utilisation of the lower levels”. According to Kuosa, this trend – the so-called dwindling food web – is evident in all seas of the world. In the Government Programme, the Finnish Government identified environmental pollution of the Baltic Sea as one of the threats to Finland. “Right now, environmental protection measures are being carried out in the Baltic Sea to remove marks of human activity. The aim is to restore the marine environment to a good state,” states Kuosa.

The Baltic Sea’s “service counter” provides fish as well as many other ecosystem services. However, product prices do not always take the resulting damage to the environment into account. “The price of a slice of bread does not include the nutrient recycling service provided by the Baltic Sea. Nevertheless, the benefits gained from reducing eutrophication in the Baltic Sea exceed the costs of water protection measures by more than four times,” clarifies Senior Research Scientist Soile Oinonen from SYKE.


Sea Spray 2015 - Meren pärskäys 2015 N.B! Available only in Finnish.

More information

State of the Baltic Sea
Leading Researcher Harri Kuosa, Finnish Environment Institute SYKE, tel. +358 (0)29 525 1106
Senior Research Scientist Seppo Knuuttila, Finnish Environment Institute SYKE, tel. +358 (0)295 251 286

Researcher Outi Setälä, Finnish Environment Institute SYKE, tel. +358 (0)295 251 635

Senior Adviser Jukka Pajala, Finnish Environment Institute SYKE, tel. +358 (0)295 251 491

Nutrient loading from agriculture
Senior Research Scientist Petri Ekholm, Finnish Environment Institute SYKE, tel. +358 (0)295 251 102

Climate change
Research Professor Markku Viitasalo, Finnish Environment Institute SYKE, tel. +358 (0)295 251 742

Social and economic impacts of the state of the Baltic Sea
Senior Research Scientist Soile Oinonen, Finnish Environment Institute SYKE,
tel. +358 (0)295 251 323

Information on the publication
Coordinator Eija Rantajärvi, Finnish Environment Institute SYKE, tel. +358 (0)295 251 542

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