Nature’s exam|The Baltic Sea is a shallow, choppy and heavily trafficked water area, where ships of increasingly poor condition pass by. The risk of an oil accident has increased in recent years, and it is at its greatest in winter.
The summary is made by artificial intelligence and checked by a human.
The risk of an oil accident in the Gulf of Finland has increased due to evasion of Russian sanctions.
The Shadow Fleet uses old and dilapidated ships, which increase the risk of accidents.
An oil spill in the Baltic Sea would be a serious environmental threat, especially during the nesting and spawning season.
Baltic Sea bacteria are able to break down oil, but slowly and under ideal conditions.
An oil spill the possibility clearly increased in the Gulf of Finland after Russia began to circumvent Western sanctions.
Since Western shipping companies no longer transport Russian oil sold above the price ceiling, Russia has started to use the so-called shadow fleet, i.e. shipping companies and tankers that do not care about sanctions.
Old, poorly maintained and poorly insured ships have already caused at least two dangerous situations in the Danish straits. The European Union has started to rein in the activities of the shadow fleet.
Special researcher Anna Reunamo
The oil spill is one of the biggest environmental threats to the Baltic Sea, along with climate change and eutrophication, says a specialist Anna Reunamo from the Finnish Environment Centre.
What factors increase the risk of an oil accident?
The Gulf of Finland is heavily trafficked, and its coast is low and rugged. Winter is the riskiest time, as the crews of paragliders are not necessarily used to sailing in winter conditions. Tricky ice makes navigation even more difficult.
How much oil could end up in the Baltic Sea?
Modern oil tankers transport more than 150,000 tons of oil. In the event of a collision, for example, 30,000 tons of oil can enter the sea, which corresponds to the contents of two cargo tanks.
If the wind blows from the west or southwest, the oil may not reach the coast. If the wind blows from the southeast or the south, the nature of coastal areas is in danger.
The oil has to be collected mainly mechanically, which is slow and cumbersome. The oil spreads in the water in a thin layer and is carried by the wind and currents to a wider area.
Some of the oil also dissolves in water layers and some sinks to the bottom of the sea. If the accident happened in winter, the ice would make collection much more difficult. The cold would also affect the properties of the oil.
Which season would cause the most destruction to marine life?
The worst time would be when the birds are nesting and the fish are spawning.
The oil weakens the insulating ability of the bird’s plumage, causing heat regulation to be disturbed and the bird to catch a cold. The bird can’t fly either. It tries to clean itself, causing oil to enter the body.
Particularly toxic are the PAH compounds in oil, i.e. polycyclic aromatic hydrocarbons. They affect, for example, the reproductive capacity of animals. In high concentrations, these compounds are lethally toxic to almost all organisms.
In fish, roe and fry are the most sensitive to oil. Studies have found that PAH compounds interfere with the development of the embryo’s eye, among other things.
Adult fish can swim to cleaner waters, but spawn and fry cannot leave the polluted area. For mammals, the oil can cause, for example, irritation of the mucous membranes or poisoning when it gets into the body.
Oil is also the most dangerous for seals, and it also affects reproduction. It has been observed around the world that seal populations have decreased after oil accidents.
How would the accident affect the subsurface living community?
For example, whitefish is very sensitive to oil. However, it and other crustaceans are mobile, meaning they are able to avoid contaminated areas to some extent.
If the oil content of the water is high, the mussel will close. It obtains food and oxygen by filtering large amounts of water. At the same time, PAH compounds would accumulate in the tissues, which have a harmful effect on the mussels. In the long term, their number would decrease.
The accident would have long-term effects on the entire ecosystem, as several species eat oil-contaminated food. Mussels are good for flounder and eel, for example.
At first, it may also seem that aquatic plants, for example, do not suffer from the accident, but they also begin to decrease over time.
Some of the phytoplankton species can even temporarily become abundant due to the effect of oil, apparently due to the temporary reduction of zooplankton. In addition, some phytoplankton are able to use the carbon compounds of oil as food.
The Natura 2000 areas and national parks of the Baltic Sea are in particular danger. They have the most endangered species and habitats, such as seagrass meadows. They provide protection for baby fish, crustaceans and mussels, for example. An attempt would be made to protect these areas with the help of oil booms.
Can Baltic Sea bacteria eat oil?
According to a study conducted in Finland, the Baltic Sea has a diverse community of bacteria that can break down the hydrocarbon compounds of oil.
If the conditions are optimal, i.e. the water is warm enough and other nutrients are available, the bacteria can break down even a large part of the oil. Biodegradation is slow in cold water and anoxic sediment.
If there was a lot of oil, it would start to be toxic to bacteria as well. We cannot be lulled into thinking that natural bacteria will save the Baltic Sea, even with the help of a biotechnological application that enhances their activity.
Research results obtained on biodegradation in other parts of the world do not directly apply here. The Baltic Sea is unique in its characteristics, and its bacterial communities differ from oceans due to, among other things, the lower salinity. More research would be needed on the matter.
Published in Science in Nature 7/2024