Alien invasion
Every year billions of tonnes of water is being transferred from port to port by the ships’ ballast water. On the side, the thousands of invasive species find their way to the new environments. This invasion is nowadays considered one of the biggest threats to oceans.
Although annually the amount of the species drifting away from their original habitats is large, many of them do not survive in their new environment. However, some does and some of these survivors are nowadays met also in the brackish water of the Archipelago Sea. Why some species survive and some don’t, still remains the mystery unsolved.
Seas are crewed more and more
Due to the increasing shipping, oil transportations and commerce, more non-indigenous species are finding their way into the Baltic Sea than ever before. Alien species are brought along not only by ships’ ballast water, but also by the ships itself. That is for some organisms can attach the body of the ship.
Even though already the Viking boats transferred species from one place to another, the scale of the drifting nowadays is drastically different. Ships transport bigger cargos from many ports to another faster than ever before, and therefore, the invasive species can also survive much longer distances.
Arctic weather does not scare off everyone
The arctic areas have usually been protected from the problems of the alien species by the cold climate. However, the global warming may facilitate the adjustment of the non-indigenous species also in here. The young age of the Baltic Sea and the exiguity of species are also making it easier for the newcomers to survive.
Brackish water is considered as one of the hindering factors for the success of the non-native species. On the other hand, many newcomers may be brackish water species for the ports are usually situated in estuaries, where also brackish water is found.
New species are already here
One of the most problematic invasive species already found in the Finnish waters is an American comb jelly, which has been nominated as among 100 of the worst invaders. The others are for example recently found Conrad’s false mussel and Cercopagis pengo, a predatory water flea which clogs fishing nets and competes with herring for zooplankton prey.
Some of the invaders are already so settled in their new environment, that they are considered to be the original part of nature. One of the representatives of these organisms is Barnacles, which came to Finland already in the 19th century.
Keep the stowaway away
To contribute the prevention of the spread of the alien species IMO, the international Maritime Organization, has framed an International Convention for the Control and Management of Ships' Ballast Water and Sediments. This convention includes the regulations about the control of the bilge- and ballast water and the water treatment facilities. The convention is to be taking into operation in phases. Helsinki commission is working on the adaptation of the contract to the conditions of the Baltic Sea region.
ASSIGNMENT 20
“Ecological roulette” is a concept related to the invasive species. Find out why these newcomers are one of the biggest threats to the aquatic ecosystems.
More information
Global Ballast Water Management Programme
