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Hello, today we visit the dolphins. Modern zoos are important forresearch in general, because we can gain important information about the animals and how they experience the world, about the sensory thresholds of the perception of the animals. Measurements like this are only possible with access to the animals, which is often impossible in the wild. If one would decide to close all zoos, these pieces fo information would be lost and this would cause big problems, because we would have to think about how to establish limits or thresholds for environmental pollution. This could be noise pollution or pollution by other substances, because for all these areas a small amount is often no problem. Quiet music is no noise pollution and doesn’t cause long-term damage, but very loud music causes damage. So it’s often a question of the does. So it’s not about saying, everything would be basically wrong. This principle can be used for pretty much all substances in the environment. If we couldn’t measure, which amount causes problems, then there are just two possibilities left. One possibility is to be very careful and establish low limits. This seems to be a nice idea, but it’s very unrealistic, because some actions in the sea like for example the building of wind farms, which are beneficial. We generate the energy we need and we generate it in a relatively environmentally friendly way. So, if we establish low limits also actions with benefits can’t be carried out. This will never happen. The society decides, that we need windfarms and they are built. If we don’t have data to evaluate, when it becomes a problem, we make up something. This is wrong in most cases. These considerations base mostly on our own experiences. The experiences of animals, especially dolphins, are completely different – they are primarly acoustic animals. They have a much wider listening area, can hear much higher frequencies than we do, have a very sensitive ear, are adapted to heard under water – a noise produced underwater, we consider as quiet, is loud for a dolphin. So you can’t establish sensible thresholds basing on your own experiences. So you can’t say: we choose this decibel value, because we think it’s good. Without research in zoos, we would grope in the dark. This is only one example, where zoos help us. There are many areas zoos are helping us to understand animals in the wild and protect them and closing zoos would be a huge disadvantage for conservation and protecting the nature as we aim to do. Facilities like Duisburg Zoo with their modern dolphin husbandry are important for science. This is because of many questions, we ask, which are very hard to answer in the wild. These questions are massively important to protect animals. One example are noise thresholds. There is a study on porpoises that has been done in a zoo and tested from when a porpoise has slight hearing loss when the animal is exposed to loud noises. This is called temporary treshold shifts, which means a temporary deterioration of hearing. As humans we know it when we visit a very loud concert, we have occupied ears or it sounds so a bit in the ears, but this disappears on the next day. It’s the same phenomenon: after intense noise pollution or a loud concert, which isn’t pollution per se, we have this slight hearing loss. This is a good indicator for problems of the ear. So that means there was so much noise, that damage can arise and in fact if one is exploited to loud noises again and again these temporary hearing impairments last longer and eventually transforms into permanent hearing loss. So that means that someday one will actually experience a permanent hearing loss. Of course, not absolutely, so that you do not hear anything, but you hear worse. These studies could really only be done with animals in zoos, because you can measure the noises animals hear in a controlled environment, but you can also measure when to stop, so you can allow the animal and its ear to recover. This kind of measurement of hearing is only possible in a zoo. In Germany, the results of this study were the basis of laws to establish the allowed value of noise pollution, if, for example, new platforms are built or a wind farm is installed etc. This is one area, where research at zoos benefit the wild counterparts of the animals. Here’s another example: we made a research on seals – you could do the same with dolphins, too – in the wild and measured what the animals are able to hear. We made one test with the wild animals and needed a comparison group. We tested a group of seals living in the north sea in an area, where many wind farms were built. During building a wind farm very loud noises are produced, especially when pile dribing is used as a method to drive a mast into the ground. This is very loud and can damage the hearing of animals. When we made this study about seals there were many wind farms and the animals were exposed to these noises. We aimed to know, if the hearing of the animals was damaged by these noises. So we made the hearing test in the wild and needed a comparison group of animals with good hearing abilities. At zoos the animals are kept for a long time and you’ve got a good history of the treatement of these animals and their circumstances. For this reasons you can use animals at the zoo as a comparison group to see, what a healthy ear hears and how an ear in the wild has suffered. These are examples you use zoo to collect data to help the animals in the wild by establishing guidelines to regulate noise pollution. If you enjoyed watching the video, please make sure to give us a thumb up. If you have more questions, wrote them down in the comments below and in order to never miss a video, subscribe to our channel for free.


  1. Author

    mehr Delfinforschung im Zoo Duisburg: 🐬 more dolphin research at Duisburg Zoo: 💦

  2. Oliver S. Author

    Wurde bei der Untersuchung der Schweinswale das Experiment tatsächlich so lange fortgeführt, bis den Tieren die Ohren klingelten und sie einen – wenn auch nur temporären – Hörverlust erlitten, um die Grenzwerte festzulegen? Obwohl ich den wissenschaftlichen Sinn darin sehe (irgendwoher muss man ja seine Daten bekommen), würde ich es vom ethischen Gesichtspunkt doch als sehr grenzwertig ansehen. Vielleicht könntet ihr die Originalstudie verlinken?
    Die zweite Frage, die ich hätte: warum werden eigentlich in Deutschland in Zoos keine Schweinswale gehalten (wie z.B. in Dänemark und den Niederlanden)? Immerhin sind sie ja die einzige heimische Delfinart, die teilweise ja ebenso bedroht ist. Dawürde sich die Art doch dafür anbieten, auch in deutschen Zoos in menschlicher Obhut gehalten zu werden, einerseits zu deren Schutz und Zucht, andererseits aber auch zur Information der Bevölkerung. Denn viele Leute denken bei Delfinen nur an "Flipper" und wissen nicht, dass es an unseren Küsten auch tolle Delfine einer anderen Art gibt.

  3. Terra-Serpentes Author

    Ein super Beitrag! 🙂
    Ja, allerdings ist es für die Arterhaltung, aber auch für die Erforschung mancher Tierarten unerlässlich dass sich private Halter und auch Zoos engagieren. Es gibt nicht wenige Erkenntnisse die wir erst diesen engagierten Artenschützern zu verdanken haben. Bei der Lebensraumzerstörung der Moderne ist es zunehmend unerlässlich, dass wir viele Arten in menschlicher Hand nachzüchten und so vor dem Aussterben bewahren. Daher ist es schlimm, dass manche radikale Organisation wie Peta den echten Naturschützern oft im Wege steht.


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