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Science TV on the trail of the predatory crustacean Dikerogammarus villosus

“Science TV”, a new DFG project, enables scientists to provide insights into their research activities. Limnologists at the University of Constance of the Special Research Area (SFB) 454 are participating in this programme. With an underwater camera, they dive into the depths of Lake Constance looking for invasive animal species such as the predatory crustacean Dikerogammarus villosus, also known as the “killer shrimp”. It is striped, about 2 cm long and has two conspicuous bumps on its back. It is extremely greedy and is gradually spreading across the entire lake. Will it displace local animal species?

Science TV makes it possible for viewers to dive into the depths of Lake Constance from the comfort of their sofas, guided by biologists and research divers Martin Mörtl, Stefan Werner and John Hesselschwerdt. The scientists are part of the Science TV project organised by the German Research Foundation (DFG), in which scientists from all over Germany provide insights into their work by becoming film-makers. The project investigates DFG-funded science projects and is particularly aimed at young people between the age of 14 and 19.
On the trail of Dikerogammarus villosus shrimp (Photo: Martin Mörtl)
On the trail of Dikerogammarus villosus shrimp (Photo: Martin Mörtl)
The limnologists from Constance University have been part of the project since December 2007. Equipped with camera and diving suits designed to withstand extreme temperatures they began their journey into their underwater research laboratory. A crash course in Bonn prepared the scientists how to competently use a camera; the cutting and audio work was done by professionals. “At first there was a lot to adapt to. We had to get used to the fact that a camera completely changed our way of working,” said Werner, talking about their film project.

In total, they have made 12 films that give insights into the scientists’ underwater work. Stefan Werner and John Hesselschwerdt are doctoral students at the University of Constance and work with invasive animal species. The crustacean Dikerogammarus villosus is such a species. It is endemic to the Black Sea area and was introduced into Lake Constance by boats. Martin Mörtl, research diver course supervisor at the University of Constance, explains: “These shrimps are like blind passengers. They attach to motorboats and sailing ships and glide across the water, detaching themselves in different parts of the lake. They can even survive dry conditions, for example when the boats are taken ashore. In this way, the shrimps continuously invade new lakes, and are reproducing with amazing speed. One hundred to one thousand animals per square metre have been observed.”

It is interesting to note that the crustaceans are always observed in the vicinity of mussel beds. Here, the crustaceans find the food they need as well as perfect hiding places from other predators. These mussel banks are in turn of great interest for water birds who find interesting goodies there. In order to test how Dikerogammarus villosus populations develop, Stefan Werner and John Hesselschwerdt installed cages weighing about 20 kilos around the mussel banks to protect the shrimps from the water birds. They then used an underwater vacuum cleaner to catch the shrimps. Shrimps from defined underwater areas were subsequently examined in the laboratory. The two scientists are hoping to find out whether local shrimps such as Gammarus roeseli are being displaced by foreign crustaceans. “We need to continue our investigations in order to be able to make definite statements about this phenomena. This is an exciting project and we will certainly be continuing regular underwater trips for quite some time,” said the scientists.

The University of Constance is one of the few German universities offering a course to become a research diver. The course is open to experienced divers who would like to retrain to become science and research divers. The next course starts on 15th September 2008.

The Science TV project films can be viewed at https://www.gesundheitsindustrie-bw.dewww.dfg-science-tv.de.

Further information on the research diver course can be found at:
https://www.gesundheitsindustrie-bw.dewww.uni-konstanz.de/limnologie/forschungstauchen/index.html

Source: University of Constance – 15th April 2008

Website address: https://www.gesundheitsindustrie-bw.de/en/article/news/science-tv-on-the-trail-of-the-predatory-crustacean-dikerogammarus-villosus