Baltic Sea habitats and species continue to be threathened by eutrophication and elevated amounts of hazardous substances resulting from long-lasting human activities in the surrounding catchment area and at sea. Since the major Baltic inflow of water from the North Atlantic in January 2003, the near-bottom water in the Bornholm and eastern Gotland Basin returned to anoxic conditions in the middle of 2004.
In 2004, spring blooms were more intensive in the Gulf of Finland than in the northern Baltic Proper and the Arkona Basin and the summer blooms of cyanobacteria were more intensive in the Gulf of Finland and Baltic Proper than in 2003.
On a positive note, concentrations of lead and PCBs in fish tissue continue to decrease.
The Baltic Sea catchment area extends over some 1.7 million km2, and is home to nearly 85 million people. Population densities vary from over 500 inhabitants/km2 in the urban areas of Poland, Germany and Denmark, to less than 10 inhabitants/km2 in northern parts of Finland and Sweden.
There are 11 cities with more than 500,000 citizens in the catchment area, and almost 15 million people live within 10 km of the coastline. Nutrients and hazardous substances originating from cities, farmland, commercially managed forests, industrial and energy plants, transport and other human activities from the whole catchment area drain into the sea via rivers. Pollutants from an even larger area can enter the Baltic from the air. Emissions and discharges from shipping and fish farms also directly enter the sea. Excessive inputs of nutrients and hazardous substances are considered to be behind the major environmental problems in the Baltic Sea. Increasing shipping raises the risk of a serious oil-spill, and also leads to the inadvertent introduction of exotic species. Commercial fisheries have also profoundly affected Baltic Sea ecosystems.
For HELCOM to protect the Baltic Sea effectively, it is vital that the monitoring and assessment of the state of the marine environment is well co-ordinated. Threats must be carefully studied; pollution inputs and their impacts of must be fully analysed; and the effects of environmental protection measures must be critically evaluated. The main role of HELCOM MONAS is to assess the inputs of nutrients and hazardous substances and their effects on the marine environment. HELCOM MONAS also co-ordinates national monitoring programmes and collects the resultant data.
The Helsinki Commission has been assessing the effects of nutrients humans on ecosystems in the Baltic Sea for the past 25 years. Resulting assesment reports are unique compilations of data and analysis based on the scientific research carried out around the Baltic Sea, including the special monitoring programmes co-ordinated by HELCOM.
The latest assessment report contains an updated scientific evaluation of the state of the Baltic marine environment between 1999 and 2002, and examines the latest trends.
The Baltic Marine Environment 1999-2002 (pdf)
The previous scientific background assesment covered the years 1994-1998
Indicator reports have been compiled in 2002, 2003 and 2004 to provide valuable information about the state of the Baltic Sea environment.
What makes the Baltic so sensitive?
The Baltic Sea, as one of the world’s largest bodies of brackish water, is ecologically unique. Due to its special geographical, climatological, and oceanographic characteristics, the Baltic Sea is highly sensitive to the environmental impacts of human activities in its catchment area, which is ca. four times larger than the sea area itself and serves as home to some 85 million people.
The Baltic Sea is only connected to the world’s oceans by the narrow and shallow waters of the Sound and the Belt Sea which limits the exchange of water with the North Sea. This means that some of the water may remain in the Baltic for up to 30 years – along with all the organic and inorganic matter it contains.
Changing natural conditions
Climatic conditions have a strong influence on the state of the Baltic Sea as they affect run-off, water exchange, and input of nutrients and hazardous waste into the Baltic Sea. All of these in turn affect the levels of oxygen in the water, and therefore also the well-being of the living organisms that inhabit the Baltic Sea.
Pollution and the Baltic Sea
The Baltic Sea is particularly vulnerable to pollution due to its unique natural conditions. Oxygen depletion is a natural problem in the Baltic, but eutrophication induced by nutrient pollution has considerably worsened this threat to marine ecosystems. Biodiversity and fish stocks have been affected as well, and exceptional algal blooms have become more common.
Due to its specific geographical and physical conditions, the Baltic Sea has higher concentrations of many hazardous substances than other marine areas, such as the North Sea. Concentrations of some metals, such as cadmium, are declining in organisms in some areas ( e.g. the Gulf of Bothnia and the Gulf of Finland) but increasing in others (e.g. the western Baltic Proper). It is not, however, possible to draw any general conclusions from the limited changes observed in heavy metal concentrations in seawater or marine organisms. The best news is the clear decrease in lead concentrations in herring observed in most areas.
Pollution from shipping
Increasing maritime transport in the Baltic poses an increasing threat to the marine environment. Even in the absence of any major oil spill, the many illegal oil discharges and accidents with minor oil spills already noticeably affect ecosystems. The predicted increase in shipping will multiply the risk of a serious spill if preventive measures are not strengthened.
Nature and biodiversity in the Baltic Sea
Compared to other aquatic ecosystems, only relatively few animal and plant species live in the brackish ecosystems of the Baltic Sea – although this limited biodiversity does include a unique mix of marine and freshwater species adapted to the brackish conditions, as well as a few true brackishwater species. Where salinity levels are low, in the Baltic’s northern and eastern waters, fewer marine species can thrive, and marine habitats are dominated by freshwater species, especially in estuaries and coastal waters.
But the limited number of species involved in Baltic Sea food webs means that each individual species has a special importance in terms of the structure and dynamics of the whole ecosystem. The disappearance of a single key-species could destroy the functioning of the whole system. Such ecosystems are considered to be very vulnerable to external disturbances.
Impacts of fisheries
Present commercial fishing practices have environmental impacts throughout the whole Baltic Sea, affecting species such as harbour porpoises, seals and sea birds which are accidentally caught as by-catches, as well as the stocks of commercially fished species themselves.
Over-fishing can put entire marine ecosystems under pressure by changing their species composition and predator-prey ratios. Over-fishing of Baltic cod is currently a serious problem.One positive sign is an increase in the productivity of wild salmon.
One sure sign of the success of HELCOM's environmental programmes and nature conservation measures is the steady increase over recent decades in the breeding success rates of top predators such as the white-tailed eagle and the three Baltic seal species. But these species still face health problems, with sterility levels high among young ringed seals.
Invasive species pose an increasing threat to eco-systems and the region's biodiversity. As shipping in the Baltic has increased during the last twenty years, more and more alien species have been arriving in the Baltic Sea as stowaways. Other non-native species have also been intentionally introduced. Inland waterways eventually connected to the Black Sea and the Caspian Sea have helped still more exotic invaders to find their way to the Baltic. Once alien species establish a foothold, they can spread into through the to other regions of the Baltic at speeds of up to 480 kilometres a year.
Non-native species can seriously disrupt ecosystems, and harm livelihoods. Fishermen in the Gulf of Riga and the Gulf of Finland remember the sudden arrival in 1992 of an alien water flea species. These tiny animals soon started to clog up the gills of fish and fishing nets, leading to serious economic losses. By 1998 the species had spread as far as Stockholm and Gotland.
To help prevent the spread of alien species HELCOM is also supporting a proposed International Convention for the Control and Management of Ships' Ballast Water and Sediments.
Chairman of HELCOM MONAS
Ms. Heike Herata
Federal Environmental Agency
P.O.Box 33 00 22
Tel: +49-30-8903 0
Fax: +49-30-8903 2965
Mr. Juha-Markku Leppänen
Tel: +358 9 6220 2227
EcoQO Project Assistant
Mr. Hermanni Backer
Tel: +358 9 6220 2220
Ms. Minna Pyhälä
Tel: +358 9 6220 2226