Experts have taken fresh samples of new invasive species, the Mnemiopsis leidyi, or comb jelly, which shows their populations were especially high in the depths of the Aland Sea, up to 3,800 individuals per square metre. It is said that the comb jelly has slowly but surely sets its foothold in the Baltic Sea.
According to the Finnish Institute of Marine Research the samples of comb jelly has been found in 78 locations in the Baltic Sea. It has informed that in the southern Baltic, off the Danish island of Bornholm, there were 1,460 comb jellies per square metre were found. In other areas too small number of this creature has been traced. Even in the Gulf of Finland between Helsinki and the Estonian capital Tallinn, this creature was found.
Researcher Maiju Lehtiniemi of the Finnish Institute of Marine Research, said that in most places the comb jelly were in poor share, many were dead. The reason might be the extreme cold temperature and low salinity of the water or the shortage of nutrition. According to the researchers the comb jellies are similar to jellyfish and they are indigenous to the east coasts of north and South America, appearing in water temperatures ranging from 4 to 32 degrees Celsius, with a salinity of 3-39 parts per mille.
These comb jellies are feed on fish eggs, newly-hatched fish, and zooplankton.
Ero Aro, a researcher, informed that the comb jellies found in the Baltic Sea appear to be prevalent in areas where cod breed. Now the population of cod fish is in danger. Baltic herring breed in shallow waters and along coastline, which means they would not be affected because the comb jellies mainly active in deeper waters.
