Water quality improves at Russian end of Gulf of Finland
Lifeless areas on bottom of main basin of Baltic Sea expand
The catch isn’t very big, but all the more significant.
It is late August and Marko Jaale, an expert in sea bottom life working for the Finnish Environment Institute (SYKE) sits on the rear deck of the research vessel Muikku, examining samples taken from the bottom of the Gulf of Finland.
Large numbers of Monoporeia affinis wriggle on the sieve. The shrimp-like creatures came up in a sample taken from the bottom at a depth of 27 metres. The ir presence on the bottom is an indication that conditions on the bottom are improving. "They are sensitive to a lack of oxygen", Jaale says.
Writhing next to them are Marenzelleria viridis, worms up to ten centimetres long. They are an invasive species introduced into the Baltic Sea in the 1990s in ships’ bilge water, and are capable of surviving in a low-oxygen environment.
When the oxygen runs out, the sea bottom turns from rust-colour to pitch black – and the Monoporeia affinis disappear.
This is the second year in a row that findings from a voyage of the Muikku in the Gulf of Finland and the Archipelago Sea has brought a spark of hope that the Baltic Sea may be on the way to recovery.
The head of the expedition, SYKE special researcher Seppo Knuuttila, says that a clear difference this year is that the water in the eastern part of the Gulf of Finland has significantly less algae than in previous years.
"There have been signs of positive development even though I cannot say how big a role the reduction of emissions has had, how much involves natural fluctuation in the state of the sea", Knuuttila says.
Nevertheless, eutrophication is clearly declining, with the water in the eastern part of the Gulf of Finland clearing up to the level that it was in the 1980s.
"Eutrophication increased in the late 1990s and culminated in 2004-2005, when the state of the Gulf of Finland was at its weakest. Now the situation is clearly better", Knuuttila said on Friday on the research vessel Aranda, where SYKE researchers presented the findings of the summer’s research. "The lower levels of algae are mainly the result of improvement in the sea bottom, which in turn is the result of improvement in the oxygen situation", Knuuttila says.
The coming years will show how the decrease in emissions from St. Petersburg, and from the Luga River will affect the state of the Gulf of Finland.
"It will be very interesting to see how much the elimination of a source of emissions as large as as the Fosforit fertiliser plant in Kingsepp will have on the amount of algae", Knuuttila says.
Further improvements in the Gulf of Finland are increasingly dependent on the state of the main basin of the Baltic Sea, and there are no signs of an improvement there. The western part of the Gulf of Finland has not shown real improvement.
"The oxygen situation in the main basin of the Baltic Sea has weakened since 2010, and areas completely devoid of oxygen have expanded", says researcher Pekka Kotilainen.
"The oxygen-free depths also contain hydrogen sulphide". When oxygen runs out, toxic hydrogen sulphide forms at the bottom, killing life on the bottom.
There was plenty of life on the bottom in the southern part of the Archipelago Sea in August. Samples taken by Muikku in the Paimionlahti inlet in the southwest of Finland showed that there is oxygen on the bottom.
"It looks good – 5.1 milligrammes per litre", says Panu Hänninen looking at the display of the sample probe. At the surface the oxygen content is twice as high.
Northern parts of the Baltic Sea are also doing well.
Previously in HS International Edition:
Waste water treatment at Russian fertiliser factory to be placed under international scrutiny (14.8.2012)
Sea bottom off Helsinki is in moderately good shape (2.8.2012)
Russian fertiliser factory near Gulf of Finland admits massive phosphorus emissions, says problem is now resolved (7.6.2012)
Gulf of Finland recovering slowly (16.5.2011)