Fish and aquatic news » WB http://www.aquaticcommunity.com/news The latest news from below the surface Wed, 23 Oct 2013 11:30:17 +0000 en-US hourly 1 http://wordpress.org/?v=3.6.1 Dragonfly nymphs responsible for the lack of frog legs (but frogs infested with nematodes may have a few to spare) http://www.aquaticcommunity.com/news/lib/374 http://www.aquaticcommunity.com/news/lib/374#comments Sun, 28 Jun 2009 03:59:12 +0000 WB http://www.aquaticcommunity.com/news/?p=374 One of the most controversial environmental issues of the past decade now seems to have been solved thanks to the consolidated efforts of one U.S. and one U.K. researcher. In the late 1980s and early 1990s, researchers started getting reports of numerous deformed wild frogs and toads. Many of them missed a limb partly or completely, while others – even more strikingly – had extra legs or extra arms.

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One of the most controversial environmental issues of the past decade now seems to have been solved thanks to the consolidated efforts of one U.S. and one U.K. researcher.

In the late 1980s and early 1990s, researchers started getting reports of numerous deformed wild frogs and toads. Many of them missed a limb partly or completely, while others – even more strikingly – had extra legs or extra arms.

The reason behind the deformities became a hot-potato, with some people suspecting chemical pollution or increased UV-B radiation (brought on by the thinning of the ozone layers), while others leaned towards predators or parasites.

awe firefly Dragonfly nymphs responsible for the lack of frog legs (but frogs infested with nematodes may have a few to spare)

“There was a veritable media firestorm, with millions of dollars of grant money at stake,” says Stanley Sessions, an amphibian specialist and professor of biology at Hartwick College, in Oneonta, New York.
Eventually, professor Sessions and other researchers managed to show that many amphibians with extra limbs were actually infected by small parasitic flatworms called Riberoria trematodes. These nematodes burrow into the hindquarters of tadpoles and rearrange the limb bud cells. This interferes with limb development, and in some cases the result is an extra arm or leg.

While these findings explained the conspicuous presences of additional limbs, it wasn’t enough to solve the mystery of the leg- and armless amphibians.

“Frogs with extra limbs may have been the most dramatic-looking deformities, but they are by far the least common deformities found,” Sessions explains. “The most commonly found deformities are frogs or toads found with missing or truncated limbs, and although parasites occasionally cause limblessness in a frog, these deformities are almost never associated with the trematode species known to cause extra limbs.”

To investigate the conundrum, Sessions teamed up with UK researcher Brandon Ballengee of the University of Plymouth. As a part of a larger research project, the two scientists placed tadpoles in aquariums and added various predators to see if any of them could be responsible for this type of injuries.

As it turned out, three different species of dragonfly nymph happily attacked and nicked of the hind legs of the tadpoles; feasting on the tasty legs without actually killing the tadpoles.

“Once they grab the tadpole, they use their front legs to turn it around, searching for the tender bits, in this case the hind limb buds, which they then snip off with their mandibles,” says Sessions. “Often the tadpole is released […],” says Sessions. “If it survives it metamorphoses into a toad with missing or deformed hind limbs, depending on the developmental stage of the tadpole.”

Eating just a leg instead of trying to kill the entire tadpole is beneficial for the dragonfly, since tadpoles develop poison glands in their skin much earlier than those in their hind legs.

Through surgical experiments, Sessions and Ballengee confirmed that losing a limb at a certain stage of a tadpole’s life can lead to missing or deformed limbs in the adult animal. Really young tadpoles are capable of growing a new limb, but they loose this ability with age.

Sessions stresses that the results of his study doesn’t completely rule out chemicals as the cause of some missing limbs, but says that this type of “selective predation” by dragonfly nymphs is now by far the leading explanation.

“Are parasites sufficient to cause extra limbs?,” he asks. “Yes. Is selective predation by dragonfly nymphs sufficient to cause loss or reduction of limbs. Yes. Are chemical pollutants necessary to understand either of these phenomena? No.”

You can find Sessions and Ballengee’s study in the Journal of Experimental Zoology Part B: Molecular and Developmental Evolution.

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Environmentally friendly aquariums http://www.aquaticcommunity.com/news/lib/92 http://www.aquaticcommunity.com/news/lib/92#comments Fri, 29 Aug 2008 03:51:29 +0000 WB http://www.aquaticcommunity.com/news/?p=92 For many aquarists, the joy of keeping an aquarium is not only about watching colourful fish dart around in the living room, it is also a way of learning more about the delicate web we call an ecosystem and how dead matter and living organisms interact with each other to create an environment where life can not only exist but […]

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For many aquarists, the joy of keeping an aquarium is not only about watching colourful fish dart around in the living room, it is also a way of learning more about the delicate web we call an ecosystem and how dead matter and living organisms interact with each other to create an environment where life can not only exist but flourish. It therefore comes as no surprise that you can find a lot of environmentally conscious aquarists, and that many of today’s expert biologists and wildlife authorities were steered into the path of environmental science at a very young age while striving to keep the inhabitants of their fish tank alive. Keeping an aquarium can unfortunately be a problematic hobby for the environmentally conscious, but don’t loose heart – there are loads of things that you can do to make your aquarium less of a burden for mother earth. As a matter of fact, many aquarists have actually helped in preservation work, e.g. by keeping and breeding endangered fish from severely damaged habitats, thus preventing species from becoming completely eradicated.

green aquarium Environmentally friendly aquariums

1.) Pick species that appreciate the same temperature as you do

Keeping an aquarium heated can require loads of energy and dig a large hole in your pocketbook. Many aquarists automatically chose tropical species in need of a temperature in the 75-82ºF (24-28ºC) range, despite the fact that they keep their homes heated up to 70°F (21°C) or so. By choosing subtropical species that prefer roughly the same temperature as you do you can save considerably amounts of energy in the long run. It can however still be a good idea to keep a heater with a thermostat in the aquarium as a precaution against sudden drops in temperature. The smaller your aquarium, the more rapidly it will loose heat if the surrounding temperature drops. Choose a supplier that sells green electricity.

2.) Never release fish or other creatures into the wild

If you for any reason cannot care for your aquarium inhabitants anymore, you need to find them a new keeper or euthanize them. It might be tempting to release them into the wild, but this is a big no-no. Releasing living organisms into environments where they don’t belong can wreck havoc with existing ecosystems and must therefore be avoided. Even if you keep species that occur naturally in your local environment you shouldn’t release them back into the wild because they may have come in contact with non-native bacteria, viruses, parasites etcetera in the aquarium that could cause problems for wild flora and fauna.

Fish are so called cold blooded animals and it is therefore easy to euthanize them by decreasing the water temperature. If you need to euthanize a fish or other cold blooded aquarium creature, simply place it in a water filled container and put the container in the freezer. As the water temperature gradually decreases, the metabolism of the animal will slow down and it will fall into a comatose like state before dying.

3.) Purchase locally bred or caught fish

Instead of purchasing fish that have to be flown in from the other side of the planet, you can search for fish that are being bred or caught in your area, country or (at least) part of the world. As a bonus for you, locally bred fish are often better acclimatized to the tap water in your area and more prone to breed in captivity.

4.) Turn your back on unsuitable harvesting methods

Unfortunately, devastating harvesting methods like dynamite fishing are still fairly common within the aquarium trade. Always make an effort to find out which technique that has been used to catch the fish you’re interested in purchasing. It can be hard to find unbiased information, but it is still worth trying. Paying a little extra for fish that has not been caught with dynamite and similar can also be a very sound investment since unsuitable harvesting methods tend to cause a lot of damage to the fish and decrease its chances of survival in captivity.

5.) Participate in breeding programs

By participating in a breeding program you can help supply the aquarium market with captive bred fish and ease the strain on wild populations. You can naturally do this on your own as well, but joining a breeding program is a great way of getting information on how to breed high quality fish and avoid common pitfalls. You may also be able to purchase or borrow hard to find species to use in your breeding efforts, especially if you have had success in breeding similar species in the past.

ecofriendly aquarium Environmentally friendly aquariums

6.) Keep the fish alive

This last point might seem like a no-brainer, but many beginner aquarists are coaxed by fish shops into thinking that four months is a perfectly normal lifespan for all sorts of aquarium fish and that you should expect to constantly purchase new fish to keep your tank populated. It is true that some species have a natural life span of less than six months, but the overwhelming majority of known fish species live much longer than this and there are actually quite a few species that will live for 10 years or more in a well kept aquarium. If all your fish goes belly up after just a few months in your tank, you’re probably doing something wrong. If aquarists all over the world would become better at actually keeping their fish alive, less energy would have to be devoted to transporting replacement fish, and it would also alleviate the strain on wild populations of desirable aquarium fish.

So, how can we increase our chances of keeping healthy and long-lived fish in our tanks? First and foremost, always read up on each species you wish to keep before you make a purchase. By learning about a species preferred environment, temperature, water chemistry, diet, tank mates, and so on, you will be more apt at keeping it alive throughout its natural life span. Do not mix species with different preferences in water chemistry, temperature and similar. You might very well be able to keep them alive, but they will not thrive and they will be more prone to health problems which increase the risk of an untimely death.

It is also important to read up on aquarium management techniques and always strive to increase ones knowledge on general aquarium maintenance. Do not hesitate to ask more experienced aquarists for advice. Today, the Internet has made it easy to keep in touch with aquarists from all over the world through aquarium forums and e-mail. If you’re lucky, there will also be a local aquarium club in your area.

20303 Environmentally friendly aquariums

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Gigantic loop hole discovered in Europe http://www.aquaticcommunity.com/news/lib/91 http://www.aquaticcommunity.com/news/lib/91#comments Fri, 29 Aug 2008 02:37:05 +0000 WB http://www.aquaticcommunity.com/news/?p=91 European Union In December 2007, the EU commission presented their suggestion for a new law that would force car manufacturers to decrease the average carbon dioxide emissions from new cars down to 130 grams per kilometre by 2012. This draft does however come with one gigantic loop hole – the new law would only target cars weighing less than 2,610 […]

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eu Gigantic loop hole discovered in Europe
European Union

In December 2007, the EU commission presented their suggestion for a new law that would force car manufacturers to decrease the average carbon dioxide emissions from new cars down to 130 grams per kilometre by 2012. This draft does however come with one gigantic loop hole – the new law would only target cars weighing less than 2,610 kg (5,754 lbs). This could actually prompt car manufacturers to start building even heavier cars than today, just to avoid the new law. Another possible escape route is to make slight alterations to the cars in order to make it possible for them to be registered as light trucks. When a similar law was put into action in the United States during the 1970s, car manufacturers immediately responded by producing large quantities of SUVs that could evade the law by registering as work vehicles. The Swedish Society for Nature Conservation (SSNC) is now urging the EU parliament and the national governments to take action and remove these loop wholes from the final draft of the law.

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Five green tips from Swedish wildlife photographer Mattias Klum http://www.aquaticcommunity.com/news/lib/90 http://www.aquaticcommunity.com/news/lib/90#comments Fri, 29 Aug 2008 02:14:54 +0000 WB http://www.aquaticcommunity.com/news/?p=90 Renowned wildlife photographer Mattias Klum, member of the Board of Trustees of WWF and fellow of The Linnean Society of London, has shared his top five green tips with Swedish newspaper Expressen. According to Klum, the birth of his two sons has made him even more environmentally conscious than before. “-I want my children to be able to experience living […]

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Renowned wildlife photographer Mattias Klum, member of the Board of Trustees of WWF and fellow of The Linnean Society of London, has shared his top five green tips with Swedish newspaper Expressen. According to Klum, the birth of his two sons has made him even more environmentally conscious than before. “-I want my children to be able to experience living coral reefs, drink water from mountain streams, and be able to take their fishing rod with them to fish and then eat their catch.

1.) Shop locally produced, ecological food, preferably of a fair trade variety. Decrease your meat consumption down to once a week or so.

2.) Take a close look at your shopping habits. Be careful with what you shop. Make fewer but more carefully selected purchases and choose high quality items.

3.) Walk and bike more; this will benefit the environment as well as your personal health. The next time you need to buy a car, choose one that is environmentally friendly.

4.) Examine how your home is heated and choose the most environmentally friendly alternative.

5.) Take action. Join WWF, your local conservation society, or some other alternative that suits you.

Do you agree with Mattias Klum? What are your top five green tips? Please share your thoughts in the comment field.

Source: (in Swedish)
http://www.expressen.se/klimathotet/1.957119/mattias-klums-fem-basta-miljotips
http://www.expressen.se/klimathotet/1.953955/fotografen-mattias-klum-tank-till-och-andra-livsstil

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