Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Otters reveal their identity - tell-tale deposits help nature protection

06.06.2008
Researchers of the Helmholtz Center for Environmental Research have developed two new methods, in order to be able to better estimate the numbers of European Otters (Lutra lutra) and their effects on the fish farming industry.

The researchers succeeded for the first time in gathering more accurate data on the otter population in the heath and pond region of the Oberlausitz Biosphere Reserve. Genetic analyses of the faeces could prove to be a promising approach when investigating otter populations, as researchers have written in the scientific journal Conservation Genetics. The new method does not only apply to otters, but also to all vertebrates.

The information can be used to ensure effective nature conservation. Accurate information on the size of the otter population makes it possible to calculate the quantity of fish eaten per pond and hence the damage incurred to the local fish farming industry. Consequently, appropriate damage compensation would improve the acceptance of otters among the local fish farming industry and thus the protection of this endangered species, as is required by national and international law. For population size estimates, the classical method of MRR (Mark Release Recapture) is enhanced by modern DNA analyses.

The frequency with which an otter visits and hunts in a body of water can be assessed more accurately if the age of the faeces are also taken into account. This second new approach improves considerably the accuracy of otter visiting rates to ponds in many situations and is not limited to the faeces alone, but can also be applied to other kinds of animal traces (i.e. feeding traces, tracks and traces from activity) according to the international researcher team in the scientific journal Journal of Applied Ecology.

Striking around at dawn: eroded fish remains bare witness the following morning to the otters feeding habits. Since these nocturnal and dawn-active animals are particularly demanding to their habitat, Lutra lutra belongs to the category of very threatened mammal species in Central Europe. These gourmet-eaters with their brown fur and many long vibrissae around the mouth are extremely shy. It is difficult enough to observe them but to catch them is nearly impossible. But how can the otter protected effectively if there are only very vague assumptions about its numbers? Experts estimate the otter population in the heath and pond region of the Oberlausitz Biosphere Reserve to be anything between 200 and 600 individuals.

"The State of Saxony pays compensation for the damage that otters cause to fish farms. Therefore a cheap and simple method is required, which can be used to estimate the otter population, so that one has an idea of how much compensation one should be paid", Dr. Bernd Gruber from the UFZ describes one of the problems. "In practice it is difficult to check the real damage. Somebody would have to go out to the site each time and take a look at the fish and otter traces, which is just not feasible."

Just like every other predator, the otter also leaves traces behind. Researchers are now using these traces, in order to be able to estimate the number of animals in an area more accurately than was previously possible. Up to thirty times a day an otter will mark its territory to indicate its presence to potential partners or competitors. "The practical thing about the otter is that it uses its droppings for the social communication and therefore leaves them exposed, making it very easy for us to find", explains Simone Lampa, who together with her UFZ colleagues collected over 700 faecal samples in the Oberlausitz over the last two years. As the cells at the surface of the intestine are constantly regenerated in vertebrates and the old cells are discarded, tiny DNA traces are found on each faecal sample therefore revealing the individual they came from. Just like in a paternity test, cotton swaps are used to take a smear, which is put into a plastic tube and sent to the laboratory. However, compared with blood or tissue samples, the DNA in faecal samples is only represented by a few cells, making it a very difficult procedure. "In addition to this there is also still the problem that a high number of proteins, bacteria and enzymes in the faeces disturb the analysis," reports Dr. Marion Hoehn, who is an expert in conservation genetics of vertebrates. "We have to extract the DNA and copy it several times in order to make it visible, which is prone to errors. The process therefore has to be repeated several times to obtain the true genotype."

Thus, the researchers were thrilled that they were able to more than double the success rate compared to earlier procedures. Their new method brings further crucial progress with it: it combines modern genetics with the classical approach to population studies using Mark Release Recapture (MRR). In traditional MMR, animals are captured, marked, and released, and eventually recaptured. During the recapture events researchers note whether the animal had already been marked or not. After several recapture periods it is possible to mathematically calculate just how many animals are present, based on the ratio of marked to unmarked individuals. For the cryptic otter this method is not feasible. In our novel approach, not the animal itself is captured but its "genetic fingerprint", which is derived from the faecal sample. For the accuracy of the population estimates it is important that faeces are collected every day from the same location within the same time intervals. The relocation rates should be as similar as possible, so as not to falsify the results with coincidental findings. The costs of this technique amounted to approximately 30 Euros per faecal sample. "That is still the more favourable option compared to having to involve numerous people in observing the area on a daily basis. It does not necessarily have to be the faeces that are collected, as it is also possible to use hair. The main thing is to get hold of the DNA. In the future this will be the standard method of estimating population sizes of cryptic species", Bernd Gruber assumes. But as is often the case, the curse lies in the detail: Attempts to determine the population size of wild cats failed several years ago, because insufficient cat hair stuck to the adhesive strips that had been set up for the samples. In spite of such setbacks Simone Lampa is also still optimistic that in the future genetic analyses will be able to tell us a lot more about wild animal populations: "In principle our procedure is applicable to all vertebrates. We just need to find the appropriate genetic markers, which mark the crucial DNA segments in the genome. These already exist for several mammal species."

So far, researchers cannot say exactly how many otters are now living in the Oberlausitz. To do so they still have to collect faecal samples from a number of places, but for a small region reliable data now exists: At the 305 hectare-study site between Hoyerswerda and Bautzen there are 32-40 otters. The new method has helped us considerably in finding out more about this majestic nocturnal swimmer in the ponds of the Lausitz.

You can read more about biological invasions and other issues concerning biodiversity in a special edition of the UFZ newsletter for the 9th Meeting of the Conference of the Parties to the Convention on Biological Diversity (COP9), that was from 19 to 30 May in Bonn.

http://www.ufz.de/index.php?en=10690

Tilo Arnhold | alfa
Further information:
http://www.ufz.de/index.php?en=10690

More articles from Ecology, The Environment and Conservation:

nachricht Preservation of floodplains is flood protection
27.09.2017 | Technische Universität München

nachricht Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Salmonella as a tumour medication

HZI researchers developed a bacterial strain that can be used in cancer therapy

Salmonellae are dangerous pathogens that enter the body via contaminated food and can cause severe infections. But these bacteria are also known to target...

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

 
Latest News

Microfluidics probe 'cholesterol' of the oil industry

23.10.2017 | Life Sciences

Gamma rays will reach beyond the limits of light

23.10.2017 | Physics and Astronomy

The end of pneumonia? New vaccine offers hope

23.10.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>