Tragic Loss Of Amphibians

Published Date: 02 Nov 2017

Why save our frogs?

It may not be apparent to everyone, however there are many organisms that are endangered in the world today, and many of these organisms are not known. Every organism plays a vital role in the balance of biodiversity. As humans, we should do our part to conserve and inhibit the survival of organisms that we may or may not be are aware of.

A prime example of this is our frogs – over the last 3 decades there has been a significant decrease and extinctions in populations of frogs worldwide.

There are many reasons as to why these amphibians have become endangered, or have been wiped out completely. This includes changes or removal in natural habitats, diseases may occur, climate change, pollution of the atmosphere, or interference by humans.

In this report, I shall address a main issue causing the death of frogs worldwide, and what is being done to save endangered species. This is known a chytrid fungus. Batrachochytrium dendrobatidis (Bd) is a chytrid fungus that causes the disease chytridiomycosis.(1) As this fungus is aquatic, it is found in the water where the frogs may swim, once it has found a host, it will burrow into the skin and infect the host. Once the fungal infection has become severe, this affects the breathing of the amphibian, as the skin is used for this process. Therefore electrolytes are not transferred correctly, and this causes the heart to fail, which causes the host to die. This fungal infection can spread rapidly. This in turn can cause a wipe out of whole species of amphibians.

‘Spread of chytridiomycosis has caused the rapid global decline and extinction of frogs’. EcoHealth 4:125-134. (2)

http://paws.wcu.edu/emcnelis/sv/presentations/chytrid/chytrid_web_page/graphs/tadpoles.JPG

Graph showing increased levels of Chytrid in tadpoles (3)

Why save our frogs?

Amphibians are essential, as they may help us survive the impacts of fossil fuel depletion; as some frogs can produce more bio-fuel from nests, compared to some plant based systems.

Some frogs provide medical solutions or benefits for humans, as their skin may contain medical benefits – such as a compound found in poison dart frogs which is more potent than that of morphine.

Many amphibians are key components within various ecosystems, and food webs. Some play important roles such as controlling aquatic vegetation and the amounts of mosquito larvae hatching etc. Therefore a loss in amphibians has had a massive impact on ecosystems and food webs. (4) Therefore it is essential to save our frogs.

http://www.sierranaturenotes.com/naturenotes/images/2004MapChytridTN.jpg

Extinctions of populations in Sierra Nevada (4)

Biological solutions (5):

- Nucleus transplants of rare or endangered frogs (Somatic cell nuclear transfer):

Frozen samples may be used. The nucleus may be extracted and placed in empty frog egg cells, and implanted into frogs which then give birth. This may be done in order to have fresh DNA and continue the survival of rare or endangered species of frogs.

An egg is obtained from a frog; the contents within the egg cell are destroyed by radiation. The egg has become enucleated and therefore empty. A different egg from the desired frog is obtained; the nucleus is extracted and placed within the empty – enucleated egg cell. The egg has therefore been transplanted with the nucleus, and is allowed to grow normally. A clone of the desired frog is produced. –As seen in the diagram below.

http://static.ddmcdn.com/gif/cloning-frog.gif

Diagram representing cloning of frogs via nucleus transplants (6)

Other/Alternate solutions:

- Amphibian Ark:

This has been set up so that animals that are at risk or endangered can live within an ex situ environment, yet live well enough to survive without becoming extinct. Animals are kept within Zoos or aquariums in order to keep them alive. This was seen at the Horniman museum, and explained by the Aquarium Curator. Animals are looked after well, and habitats are well built in order to mimic that of the natural habitat in order that organisms are comfortable in order to survive.

- Manage population:

Humans may collect specific or endangered samples of frogs. These eggs maybe swapped with other frogs of the same species or with those which have a immunity or low level protection to the fungal disease, in order to breed ‘cousins’ instead of ‘siblings’ in order to have a more biologically and genetically diverse population of frogs, with an immunity to the chytridiomycosis disease.

-Inoculation of frogs:

As chytridiomycosis is a fungal disease, a cure can be produced for this disease, or DNA from the skin of frogs with a barrier or immunity to this disease can be extracted and injected into frogs in order that they are also immune to the chytridiomycosis disease in order to create a cure. However there is still a lot of research and development being undertaken within this.

Medicine has been developing; stem cell research may be much beneficial as this means that there is no testing on animals, and this method is quicker and efficient.

http://static.guim.co.uk/sys-images/Guardian/Pix/maps_and_graphs/2012/8/30/1346327916124/Map---spread-of-chytrid-d-001.png

Showing the spread of Chytrid (8)

All of these methods are currently being used in order to save endangered species, and have so far been effective, however the chytridiomycosis disease has not been completely eliminated. More research is still underway in order to understand the complexity of Batrachochytrium dendrobatidis and its implications; as there is no direct way into eliminating the chytridiomycosis disease.

WAZA and other associations have been involved within the research and conservation of endangered species. Amphibian Ark and the management of population have had the most successful outcomes, as amphibians have been tested to see if they suffer from the chytridiomycosis disease, however more funding and research is still needed in order to determine a specific cure for the chytridiomycosis disease; in order to save endangered amphibians.

bi.jpg nio.jpg

British pond frog and Amazon milk frog. Both may be endangered, and therefore placed within Amphibian Ark settings. *

Benefits and limitations:

With every method there are benefits and risks involved. The benefits of the nucleus transplant and the other methods involved, is that they can be used to save endangered or populations of frogs which may have become extinct. These animals play vital roles within ecosystems, so their survival plays a key role within the world today. These methods have proved to be effective, as animals that may have become extinct, have been cloned and therefore saved. They have been able to produce more of the species, and therefore save these amphibians from extinction.

Cloning may not always be successful, processes may go wrong, and in the end eggs and nucleus’ may go to waste, therefore reducing the rate of survival for these amphibians.

Although animals have been cloned, there is no direct immunity from the disease, many organisms may never be reintroduced into their natural habitats, and therefore this is a limitation, as animals may not be observed within in situ environments as there is always a risk of the chytridiomycosis disease wiping out populations of frogs, as there is no specific cure yet discovered for this disease.

Ethical issues:

With the procedures listed above, there are many implications that may arise, such as:

-It may be unethical, as frog eggs are being frozen and artificially fertilized and then reintroduced. Humans are tampering with life, and every organism has the right to live its life naturally within its own habitat without the interference of others. Cloning may cause a lack in diversity, and therefore an artificial environment may be created of that in which all frogs are immune to the disease.

-Keeping animals in captivity, this may be cruel and unethical to take them out from their natural environment. However, we should ensure animals are comfortable and happy within their new environment (ex situ) in order for them to survive.

-It may not be ethically right for us to intervene and breed frogs that may have skin immunity to the fungus or a low level barrier to chrytid, as organisms should be left to breed naturally and create offspring that may or may not have the immunity to this fungus.

- Inoculation or managing population may not be simple, other factors may be involved such as diet and habitat and therefore intervention may disrupt these factors and cause a negative effect. It may be unethical to introduce foreign chemicals into a frog, a reaction may occur. Also, you would not be able to inoculate all the frogs in the world, as some have not yet been discovered.