When plants and animals hitch a ride to foreign lands
Scientists from Oldenburg and Frankfurt have modelled how the global shipping routes leads to the spread of invasive plant and animal species. According to them, an increase in invasion can be expected to take place in the future, especially in regions with high shipping traffic and rising temperatures.
The conclusions of the study have been published in the latest issue of Proceedings of the National Academy of Sciences (PNAS).
Cargo ships travel the world and connect countries with one another across vast distances. The intruders brought into the new environment can alter entire ecosystems and cause billions in damage. The new modelling method, developed under the auspices of the University of Oldenburg's Institute for Chemistry and Biology of the Marine Environment (ICBM), can also be used to predict future invasions of animal and plant groups.
According to lead author Dr Hanno Seebens from Senckenberg Biodiversity and Climate Research Centre in Frankfurt, these trading networks transport not only goods but also plants and animals which arrive as stowaways and spread across the world. A variety of species can be found travelling in ship hulls and ballast, and managing to survive the long journey, for example, from Singapore to Hamburg.
Essentially, with the introduction of such human activities, these plants and animals reach areas that they otherwise could not have reached, said Dr Seebens.
Together with colleagues from the ICBM and Senckenberg Biodiversity and Climate Research Centre, he developed a method of modelling such invasions. “It is important to know when and where animal species migrate into our oceans, so as to avoid or reduce their negative effects,” Dr Seebens added.
Professor Dr Bernd Blasius, university lecturer of Mathematical Modelling at ICBM, explained that for the simulations, they had used a mathematical model which combined information about ship movements and size with water temperature and the salinity of the water to determine the likelihood of an invasion.
Similar models had been applied before, but without much success. Hence, the researchers adjusted their calculations and also integrated the distribution maps of potentially invasive species to enable them to predict the type of species likely to be introduced to a particular marine region.
According to the study, the North Sea is expected to experience more instances of invasions. The reason for this is the similar conditions in the North Sea with the seas around Japan and China. In addition, these areas are well-connected by extensive shipping routes. “In the North Sea, we had classified two new algae species – Prorocentrum minimum and Polysiphonia harveyi – as high-risk species. Our predictions have been confirmed,” said Seebens.
More invasions are also expected at the western coast of the United States due to climate change and the associated rise in water temperatures. This region is often visited by ships from Asia; but most species from Asia did not survive the relatively colder temperatures. Seebens said: “Climate change increases the risk of an invasion – there; we are seeing the first invasions from Asia as a result of increased water temperature.”
See also article: Misadventures with comb jellies
Further Information: www.senckenberg.de
Link to study: www.pnas.org/.../1524427113.abstract