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
Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen
A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems Holding GmbH about commercial use of a multi-well tissue plate for automated and reliable tissue engineering & drug testing.
MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
21.09.2017 | Physics and Astronomy
21.09.2017 | Life Sciences
21.09.2017 | Health and Medicine