Pictures of glass jellyfish close in close in huge clusters in the Oslo Fjord and along the southern coast have appeared in several media over the last month.
Along the coast in southern Norway, in the Skagerrak and also up to the western part of the country, large accumulations of fire jellyfish have been reported.
Researcher Tone Falkenhaug at the Institute of Marine Research tells NTB that it is quite common that there are a lot of fire jellyfish in some areas at this time of year, but that there have been relatively many glass jellyfish along the southern coast and in some places in the Oslo Fjord.
– What is special is that there are quite a lot of glass jellyfish quite tightly in some areas, she says.
Unknown
The jellyfish can cause problems with bathing, and jellyfish have been cleverly ingested in refrigeration plants, creating problems for fish farms and shrimp trawlers.
There may be several reasons why large quantities of jellyfish appear in the water surface close to land, and that in some years there will be many, but much is unknown when it comes to jellyfish.
– There may be several factors. Unfortunately, little research is done on jellyfish, so we do not actually know what makes the individual year very much, says Falkenhaug.
Glass and fire jellyfish have a bottom-up stage throughout the winter, and many jellyfish may indicate that they have had good conditions as they multiply, with the right temperature and good food supply.
– Impossible to predict
The researcher explains that although there are many jellyfish in the water nowadays, they may not be lying all summer long.
– It is absolutely impossible to predict what summer jellyfish will be like, says Falkenhaug.
Ocean currents, wind and surface temperature determine whether the jellyfish pull down to deeper water. Offshore winds that pull the warm surface water away from the coast may draw deep water and jellyfish up to the surface near land, according to the researcher.
The Institute of Marine Research does not have a complete overview of the jellyfish situation, and it is difficult to get since the jellyfish can pull into the water and then you get the impression that there are fewer of them.
Not dangerous to be burnt
Although it is not tempting to jump in the sea in areas with large jellyfish bodies, jellyfish are not considered dangerous in the first place. But if you are allergic, you should be careful, explains Falkenhaug.
– If you get burned on a large area of the body and you get ailments, you have to see a doctor, she says.
Glass jellyfish can also burn, but very weakly. The nasal cells are so small that they do not pass through the skin. With jellyfish, as you know, it can be far more unpleasant.
(© NTB)
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