Up to 10.000 organisms can be found on a square meter of water bottom, of which a lot are also terrestrial insect larvae. Scientists call the whole group macrozoobenthos - these are all invertebrates living on the bottom and still visible with naked eyes. Researchers at the Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB) now study the impact that ship-induced waves can have on these small animals.
The larva of Calopteryx splendens, a dragonfly, crawls on a stone in shallow water. Then operates Friederike Gabel the wave machine. A wave, comparable to that of a sport boat, runs along the three-metre-long canal. The larva is washed out - "detached" say the researchers - and paddle around several minutes helplessly in the water until it found again the "solid ground" under its feet. “If they stay suspended in the water, the larvae take the risk to be eaten" explains F. Gabel, a specialist of the effect of waves on invertebrates. In addition, the larva spent energy to fix them back, which has negative effects on their growth and reproduction. The researchers fear that ship-induced waves increase larval mortality and subsequently biodiversity, which would have a long-term effect on the ecological quality of rivers and lakes.
Using an experimental set up, they have defined in laboratory for which threshold of wave strength the animals will be washed out from their standing place. The results are now published in the journal Freshwater Biology (2008, 53, 1567-1578). They found that the more complex was the structure of the habitat, less massive was the detachment. "The impact of waves is the lowest, when the shore is covert with tree roots," explains F. Gabel. Even dense reed belts would provide a sufficient protection against the power of the waves to the animals. On the contrary, the detachment is maximal on sand and stones. Complex habitats reduce the impact of waves since they offer better hiding place and fixing possibilities for the animals, explains F. Gabel.
The researchers have now begun to collect samples in natural habitat. They want to determine the long-term impact of ship-induced waves on the invertebrates inhabiting the shore. They survey different locations of the River Havel and compare shore sections differently exposed to ship-induced wave intensity.
We are not against the ship traffic, stresses F. Gabel, however there is a need to find simple measures to protect the shores. "As a result of our investigations we could make recommendations for water management, such as the design of the shores or, that ships in certain areas should pass by far away from the shore or should lower their speed" said the scientist.
Christine Vollgraf | alfa
Safeguarding sustainability through forest certification mapping
27.06.2017 | International Institute for Applied Systems Analysis (IIASA)
Dune ecosystem modelling
26.06.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.
For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...
What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.
To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...
The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....
A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...
Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision
Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...
21.07.2017 | Event News
19.07.2017 | Event News
12.07.2017 | Event News
21.07.2017 | Earth Sciences
21.07.2017 | Power and Electrical Engineering
21.07.2017 | Physics and Astronomy