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Leaping Into Action: Protecting Amphibians From Extinction
First Of All: What Exactly Are Amphibians?
We are going to start with the basics.
The Class Amphibia (or amphibians) includes three Orders:
- Anura (frogs and toads) which has about 6,500 different species.
- Caudata or Urodela (newts and salamanders) which has about 680 different species.
- Gymnophiona (caecillians) which has about 205 different species.
Most people are already pretty familiar with the first two, but almost no one has ever even heard of caecillians. Mostly, they look like giant earthworms. Very little is known about them because they spend most of their time hidden in places underground or underwater.
- Animals that are cold blooded.
- Animals that metamorphose from a juvenile to an adult form (example: tadpole to a frog).
- Animals that cannot generate their own body heat so instead they have to rely on the temperature in their environment in order to keep warm or cool enough to survive.
There are 7,500 different species of amphibians all together and they can be found on every single continent except for Antarctica. Their habitats vary from rainforests, rivers and streams, alpine environments, and deserts.
Why Are Amphibians Important?
Most people when they see a creature such as a frog or a salamander they may think to themselves, "ewww, that's slimy and gross!" But the truth is amphibians are actually quite beneficial to the environments that they live in in several different ways.
The Benefits of Amphibians:
- Amphibians are great at pest control, eating pest insects that carry diseases such as malaria and insuring that successful agriculture happens by keeping insects from ruining crops.
- They play important parts as both predator and prey, for although they eat lots of pesky insects, amphibians are also a big food source for plenty of other creatures. Without amphibians, insect populations would increase and many other creatures would go extinct from not having enough food to eat, which may cause them to either die or turn to other food sources which would then cause entire ecosystems to collapse.
- The amphibians' skin has substances that protect them from various microbesand viruses and could provide important information in the fight to cure diseases such AIDS.
- Frogs have also held special places in various cultures for centuries, symbolizing fortune and good luck.
Also, successful human collaboration to protect amphibians also allows us to keep an eye on and good a good idea about the health of our surrounding environment here on Earth. Amphibians are always one of the first species to be effected by major changes to the environment, which means when their population numbers show significant declines in the wild, it is a huge warning sign that something is happening that could have a negative effect on other species, including us humans.
Amphibians on The Decline
Amphibian populations are declining at extremely alarming rates. About one third of the world's species are endangered. If this is true, experts say that this could be the largest mass extinction event since the dinosaurs. Currently, 122 different species have gone extinct since 1980 and of the 7,500 species that we know of about half of those could become extinct in our lifetime.
Threats to amphibian species include:
- Habitat destruction
- Invasive species
- Climate change.
In addition to these dangerous human influences, there is another major threat to amphibian populations on the horizon, one that is both silent and deadly.
The Silent Killer: Amphibian Chytrid
Chytrid fungus is a deadly disease that infects the skin of amphibians, a vital organ that many species use to breathe and even drink through and it has caused detrimental and unprecedented population die offs. In fact, it has been identified on all six amphibian inhabited continents. It is a disease that has decimated entire species, killing so swiftly and quietly, that many species have been wiped out before anyone even knew they were in trouble, killing as much as 80% of a species' population within months of being introduced to a new area.
Currently, the disease is both unstoppable and untreatable in the wild. Even so-called "protected' areas have been decimated by this horrible fungus. Scientists have been doing everything that they possibly can to keep populations from going extinct, collecting specimens from the wild in order to create so-called "amphibian arks" in order to preserve species until a solution can be found.
What is a "Chytrid?"
A "chytrid" is a kind of fungus and there are approximately 1,000 different kinds that live in exclusively in water or moist environments. The chytrids are the oldest, and therefore most primitive, types of fungus and until very recently they were considered to be members of the Kingdom Protista (and therefore they were once thought to be related to single-celled organisms like Protozoa). In 1999 a new type of chytrid was discovered and identified.
Batrachochytrium dendrobatidis, also known as bd, is a type that is extremely virulent fungus to vertebrates, more specifically amphibians. It has been found in a wide range of species and habitats including lakes, natural forests, riperian zones (the interface between land and streams or rivers, and water courses (the channel that a body of water flows. These include rivers, streams, and canals). The fungus prefers low temperatures, which could explain why there are much higher concentrations of it in the tropics. Most chytrids are saprobes, meaning that they feed on dead and rotting organic matter. Other chytrids are parasites that live on plants or invertebrate animals. Bd is the only kind of chytrid that is a parasite that infects vertebrate animals amphibians specifically (it has not been observed to infect birds, mammals, or reptiles). The name is hard to pronounce, even for most scientists, but roughly translated the name means, "frog chytrid". It appears to be able to infect most of the world's 7,500 species of amphibians and many of those species have developed the disease chytridiomycosis which as been linked to devastating population declines and species extinction. In fact, infection caused by Bd has been called the most infectious disease ever recorded among vertebrates in terms of the number of species that have been impacted.
How is Bd Killing Amphibians and what is Chytridiomycosis?
Chytridiomycosis occurs when large numbers of Bd infect an amphibian. The disease takes an extremely fast acting course, starting with the animals first encounters with the zoospores which are motile flagellated asexually produced spores, of certain algae, oomycetes, and fungi. Then the amphibian's skin quickly gives rise sporangia which quickly produces more zoospores. Once the fungus has gotten a hold of the host. Once that happens morphological changes begin to occur including reddening of the ventral skin, convulsions with extensions of the hind limbs, sloughing of the superficial epidermis of the feet as well as other areas, slight roughening of the skin area with minute skin tags, and occasional small ulcers or hemorrhage. The animal may then become lethargic, lose the ability to find proper shelter, adopt an abnormal posture, and lose the ability to right itself. Death usually occurs in 2-3 weeks. The cause of death is unknown. The fungus may give off a toxin or it might be due to physical changes affecting respiration. The infection occurs inside the outer layers that contain large amounts of keratin (the substances that human hair and fingernails are made of) which allows for it to be more resistant to injury. Amphibians "drink" and absorb important salts (electrolytes) such as potassium and sodium instead of through their mouth. Abnormal electrolyte levels are due to Bd-damaged skin which can cause the heart to stop beating and could result in death for the animal. Other amphibians besides frogs, such as lungless salamanders, breathe air through their skin, and skin changes thanks to chytridiomycosis can prove deadly, resulting in suffocation. Tadpoles are not effected due to the fact that they lack keratin, but as they begin to turn into their adult counterparts, keratin becomes present and the fungus can then take hold and then start to infect the keratinized parts. Adults who have been infected have been known to attempt to breed and their offspring may already be infected with the fungus, but the evidence of this is still extremely vague.
Frogs in captivity are not safe from this fungus either as it has been identified in captive populations as well.
Climate Change and Its Effects
As previously mentioned, this kind of fungus thrives in lower temperatures. Optimum growth of zoospores occurs faster at 23°C and slower at 28°C. The fungus cannot stand and dies at temperatures that are above 86°C. When frogs that were infected with the fungus were moved from areas that had hotter temperatures into areas that had lower temperatures, they ended up with a 25% increase of the fungus. It is possible that the frogs ability to secrete fungus-fighting skin secretions is temperature sensitive and while the the world's changing climate may not be causing the rapid decline directly, it may be providing the optimum conditions for Bd to and reproduce more rapidly, allowing for the death of more amphibians.
How Can You Help?
The rapid disappearance of amphibian populations that has been happening in recent decades is a devastating loss to our biodiversity and is a serious problem that needs fixing RIGHT NOW.
Here are some ways that YOU can help keep our amphibian friends from disappearing off of the face of the planet:
- Don't use pesticides! Pesticides are toxic chemicals that go through little to know testing on amphibians prior to their approval to use. Unfortunately, the law of gravity almost always prevails here on Earth, and many of these pesticides end up in waterways, polluting the water supplies where these animals live and breed. Unfortunately, amphibians have permeable skin that is highly absorbent. Atrazine, which is probably one of the most commonly used pesticides has been known to cause hermaphrodatism in frogs which can cause male frogs to grow female sex organs if applied in ecologically relevant dosages and can reduce survivor-ship in salamanders. Atrazine also effects the water supply in lakes which causes an increase in the population of snails. These snails serve as an intermediary host to a trematode parasite which can burrow into the skin of tadpoles and cause abnormal limb formations. Roundup is lethal to grey treefrog and leopard treefrog tadpoles (it's also sold as Touchdown Total). Roundup is the second most widely used pesticide in the U.S and it is produced by Monsanto. Over half of the DNA found in frogs can be found in humans. So, imagine this: if these pesticides are so dangerous to frogs, what are they doing to us?
- Don't Eat Froglegs! Europeans alone consumed up to 120 million frogs per year in the 1990's. The harvesting of amphibians for food is often under regulated, and in many underdeveloped countries, it is likely a contributor to amphibian population declines. Even in places where the trade of different species is controlled, there are little to no protocols in place to ensure that diseased amphibians do not get transported. Bullfrogs, are transported worldwide and they are known carriers for Bd. In fact, in a recent study, about 62% bullfrogs that were being sold in pet stores in New York, L.A. and, San Francisco tested positive for the Chytrid fungus.Bullfrogs are also quite good at establishing populations in areas where they are introduced. They are large and invasive species that compete with other, native amphibians for food and shelter and they can be devastating on populations outside of their native range (the eastern United States).
- Do Not Purchase Wild Caught Amphibians. Do your research and figure out where your amphibian may be coming from if you insist on purchasing one as a pet. More than 20 million wild caught amphibians are sold on the international market every single year, and many more get sold domestically and illegally, thus making the trade a significant contributor to amphibian population declines (the more amphibians that are caught, bought, and sold, the less there are in the wild). It has been strongly suggested that any potential amphibian pet you purchase be captive raised, preferably locally, and that it is best to stick to native species. Make sure the place you purchase your pet from gives you the exact details on the origin of your pet and make sure that it is not one that is listed as vulnerable, threatened, or endangered (if it is DON'T PURCHASE IT.) Never release a pet amphibian back into the wild unless it is being taken to its exact point of origin and it is has been through extensive diagnostic testing.
- Amphibians on the road. Roadkill is a significant contributor to the decline of amphibian populations. The best thing to do is to drive slower on wet nights, and if you see a frog or toad in the road, stop and help it across if it is safe enough for you to do so. Some groups even organize events, specifically to help amphibians cross roads.
- Do not introduce non-native fish to your pond or stream. Fish are voracious predators of frog eggs and tadpoles. and will eat large amounts of them. If you're local pond is stocking fish, make sure they are using only native fish.
- Build a frog pond behind your home or school so that frogs have a nice place to live.
You can find more ways to help frogs and other amphibians at http://www.savethefrogs.com/how-to-help/
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For More Information....
- Association of Zoos and Aquariums - Amphibian Conservation
AZA and its accredited institutions provide conservation and education resources, subsidize research and conservation projects, manage a citizen science program, and maintain partnerships to raise awareness of the amphibian crisis and promote amphibi
- Project Golden Frog
- Amphibian Ark-Saving Endangered Amphibians from Extinction
Global amphibian decline threatens frogs, toads and salamanders with extinction. AArk is saving endangered amphibians with ex situ amphibian conservation.
- SAVE THE FROGS! - The World's Leading Amphibian Conservation Organization
SAVE THE FROGS! is the world's leading amphibian conservation organization. We are dedicated to protecting the world’s amphibians: the frogs, toads, salamanders, newts, and caecilians.