Several invasive species have increased in the Skagerack and Kattegatt in recent years.
Now a Nordic research project is starting to stop the spread.
– This is one of the five biggest threats to the earth’s biological diversity, says Björn Källström, marine biologist and researcher in the project.
It is no bigger than a couple of centimetres, but the bladder crab, together with around 50 other invasive species, poses a danger to biological diversity. In the Climate invasives project, researchers from the three Nordic neighboring countries around the North Sea will collaborate to find out more about the new visitors who threaten to displace native species and disrupt the ecosystem.
– In addition to the blue crab, we look at the brush crab, the clinging jellyfish, the oyster drill and the felt sea urchin, says Björn Källström.
Wants the public’s help
The species often reach Swedish waters by ship and then spread with currents to new locations. To find out more about how these currents move, the project will launch so-called drifters, a kind of floating buoy, whose data can then be entered to see where there is a risk of spreading.
The project runs until 2025 and in the meantime it is hoped to get the public’s help in finding and reporting what and where unwelcome species have been found. Björn Källman describes how the common Swedish beach crab that is part of our marine flora has an almost hexagonal shell, while the invasive blue crab is more square and has striped legs. If you find it, please report the find on SLU’s species database rappen.nu.
– We researchers are quite few, so we train ordinary people to become so-called citizen researchers. This means that there will be significantly more of us who can discover the species. Crab-fishing children, for example, can be very helpful.