Unique Frogs and the Decline of World Frog Population

This is one of my favorite websites. Generally when you think of frogs, you may think of a bullfrog, a poison dart frog, or Kermit. But most people aren't aware of the vast diversity of Order Anura, or frogs and toads.

Frogs consist of more than 5,000 species described and they are among the most diverse groups of vertebrates. However, populations of certain frog species are declining significantly. Of the thousands of species of frogs, here are the most bizarre and oddest-looking.

Weird Frogs

So, the author of this site mentioned hat there is a decline in frog species. While you enjoy those awesome frogs, let's try and figure out what is wrong with the frog populations all over the world. Frogs, like all amphibians, respire through lungs and skin. Their eggs are also shell-less. This means that they are especially vulnerable to changes in their environment because in many ways, the conditions of the external environment become conditions inside these organisms. Here are some possible explanations. The truth is that right now, scientists just don't know what the problem is. They're attempting to treat each one of the causes, such as isolating and disinfecting frogs infected with Chytrid or removing frogs from areas with parasites.

Chytrid Fungus (Bd):
www.amphibianark.org...

From the site of its introduction, Bd spreads through water courses and amphibian-to-amphibian contact, and possibly by other mechanisms not yet fully understood. In Central America, where the spread of Bd has been extensively studied, its rate of progression has been calculated at 28-100km/yr.
Where Bd thrives, generally moist cool habitats, 50% of amphibian species and 80% of individuals can be expected to disappear within 1 year (Lips et al. 2006; www.amphibianark.org/Lips%20et%20al%202006.pdf). Currently it cannot be stopped in the wild and a minority of species seem able to survive with a Bd infection as larvae or as adults and these animals likely serve as a reservoir and vectors for future outbreaks. Notable among resistant species are worldwide invasive pest species including marine toads, American bullfrogs and African clawed frogs.

Pollution and parasites:
www.sciencedaily.com...

The study showed increased levels of nitrogen and phosphorus cause sharp hikes in the abundance and reproduction of a snail species that hosts microscopic parasites known as trematodes, said Assistant Professor Pieter Johnson of CU-Boulder's ecology and evolutionary biology department.

Pesticides and parasites:
media.www.ramcigar.com...

Five years ago there was a study in Wyoming; 92 percent of the frogs had abnormalities in the contaminated areas. Five years later the study was and the same area was no longer contaminated with Atrazine. In addition, there were no chemically castrated frogs found. According to Hayes and his studies, these frogs are more likely to be found in areas with Atrazine exposure.

www.npr.org...
www.recordnet.com.../20070608/A_NEWS/706080327/-1/A_NEWS

In California, this decline has spanned 15 to 20 years. Experts say they are not aware of a single frog population that has significantly increased during that time, while many have disappeared.

Invasive Species:
Not only do invasive frogs and toads compete with native frogs and toads for food, but they also are carnivorous and eat the native species.
sofia.usgs.gov...
nationalzoo.si.edu...

This species of African clawed frog is neither threatened nor endangered. Presumably as a result of pet release, they have been introduced into Orange and San Diego counties in California, Arlington, Virginia, and Delaware, where they are now pests, devouring native wildlife such as fish, frogs, tadpoles.

Deforestation:
If it's making frogs smaller, is it making some species disappear altogether?
www.newscientist.com...

Remarkably, the team found that frogs collected in habitats with foliage coverage of 20% or less were physically 5 to 10% smaller than those collected in habitats with 70% or more foliage cover. They also found that the frogs collected in more disturbed habitats had bodies that were less symmetrical than those in pristine areas.

Birth Control Pills and Hormones in Water:
www.exploratorium.edu...

The sex hormones that control reproduction and development in humans control many of the same functions in frogs. The effects are most critical to both species during early development. For example, some tadpoles exposed to androgens never develop into adults. "If you saw them in the field," says Hayes, "they look like big healthy tadpoles, but they never develop into frogs. The hormone inhibits their thyroid gland so they're stuck in the tadpole stage."

Climate Change:
If it's killing toads, is it killing frogs, too?
www.anapsid.org...

That still is a factor, the researchers say, but it also appears to involve a synergistic effect with the actual depth of the water. Quite simply, deeper water shields the toad eggs from some of the damaging effects of UV-B radiation. The toads have evolved to always lay their eggs in the same location with relatively shallow water that, in the past, apparently provided the optimal combination of warmth for quick hatching and adequate protection from UV-B radiation. But when the water levels dropped too low at that location due to lower winter precipitation, the eggs were exposed to much higher levels of UV-B radiation, the scientists found. They then weakened and became vulnerable to the opportunistic fungus that ultimately killed them by the thousands.

Increased Noise:
www.physci.ucla.edu...

Our experiments not only document the
impact of exogenous sounds on anuran amphibian
choruses, but also bring to light the possibility of a
human disturbance differentially affecting members of a
multi-species community.

Earthquakes:
news.mongabay.com...

Before the earthquake, nearly 3,000 frogs were identified in numerous surveys over three years of study at the site. After the earthquake a total of 274 frogs were found in almost two years. As well, previous to the earthquake, the site had tadpoles from November to April, afterwards tadpoles could be found year-round, but at numbers 100 times less than before. From this data, it is obvious the earthquake significantly depleted the population or caused a massive migration.

Some Statistics:
www.amphibianark.org...

50%: of ~6,000 described amphibian species, are threatened with extinction. 32% known to be threatened + 23% data deficient but believed threatened; ~3,000 species are in trouble.

165: number of amphibian species believed to have already gone extinct, including 34 known to be extinct, 1 extinct in the wild but still survives in captivity, and 130 not found in recent years and possibly extinct.

500: estimated number of amphibian species whose threats currently cannot be mitigated quickly enough to stave off extinction, i.e., those who require ex situ intervention.

10: number (not percentage) of amphibian species North American zoos are currently prepared to manage long-term.

50: that same number extrapolated (extreme best-case scenario) to the global zoo community.

10%: portion of amphibian species threatened with extinction that the global zoo community is at best currently prepared to manage.

My guess is that it's a combination of all the factors, and Chytrid and deforestation are mainly responsible in remote areas, and that pollution is responsible in more urban areas, and invasive species are responsible everywhere. But regardless of the cause, these amphibians are decreasing and decreasing quickly. We do not even understand nor have identified many species of frogs, and just as we are learning more about them and how they can help us as bioindicators and in fields of research, they are disappearing. Enjoy the awesome frogs while they last, because in ten years many of these species may be extinct.

For more information and for those who are interested, I'd like to direct you to PBS' series "The Thin Green Line" available here: www.pbs.org...


[edit on 5/24/2009 by ravenshadow13]

Not to bump my own thread,
But I had been wondering what everyone else thought the cause of the decline in the anura population was. Or if anyone had an alternate suggestion that I did not include.

I'm glad everyone is enjoying the thread, though!

reply to post by ravenshadow13


Very interesting. I love sites like this because of this type of information. My daughter's favorite creatures in the world are frogs. This is why our little camping vacation this past week at Delaware State Park in Ohio turned out to be a bit of a bummer for her. Frogs are usually very easy to find around lakes and forests. We always find tons.

This year we went searching for frogs and found about 9. Here is the disturbing thing that we found. Of the 9, 7 of them were deformed in one way or another. The first tree frog we found had knobs at the bend in its back legs instead of the foreleg and feet. Just blobs of flesh. It could hardly jump. The others had issues like extra limbs or they still had their tadpole tails. The thing is that these were fully developed adults and not adolescents. They were simply deformed. One frog, although I marvel at how life always finds a way to survive, had no eyes.

It's getting bad. For those that think there is no global warming I tend to want to side with you. However, if you also beleive our impact on this planet is very tiny and virtually negligable, well, just go frog hunting around populated areas and see for yourselves.

Do deformities happen naturally? Sure. That's what most evolutional changes are. However, do they happen in 7 out of 9? Not naturally.

Yeah yeah, it could have been a lucky coincidence that we just happened to find so many deformed frogs. You see, I don't like coincidences. Not when so many happen at once. It begins to become a pattern then and we leave the realm of coincidence. Which is why I also have serious issues with the 'official' story of that fateful day now almost 8 years ago.

reply to post by ravenshadow13


I would agree that it is likely due to human pollution. The Bee population is also vanishing, and the Bats I believe. I hope it gets under control.

reply to post by jkrog08


www.abovetopsecret.com...

Covered the bees here, hahaha.

I hope it gets under control, too.

reply to post by dariousg


It's awful. I feel awful taking medications knowing that they will end up in the groundwater and affecting frogs. They're just such sensitive organisms. They don't have much protection against anything toxic in their surroundings.

huh, this is very odd. I, myself used to have frogs, but after Katrina we couldn't find them (I wonder why..lol) anyway. I know frogs are VERY important to the ecosystem and losing them would definately bring a HUGE downfall in the ecology and biology of other organisms. Much like bees, frogs are a necessity. Hopefully, this gets under control and Fast.

Starred and Flagged, excellent.

reply to post by TheMythLives


Things like Katrina are one of the reasons why we have invasive species. I mean, it's totally not your fault. But stuff like that happens.

I've actually got two albino dwarf African clawed frogs living in my zoology classroom that I might be taking to college with me in the fall. They're sweeeeeeeet frogs.

But I'm pretty sure they would die if they got outside of their fishtank.

Frogs are bioindicators. If they disappeared, we wouldn't know what was going on with some parts of the world's ecosystems.

Have you seen this website:

dieing amphibians- its time to step in

The Global Amphibian Assessment (GAA) revealed that almost a third of amphibians is threatened with extinction. In response to these alarming findings, a Summit was convened in Washington, DC in September 2005 to craft a response by the International community. The resultant Declaration outlined four interventions that would be necessary to stem the crisis. It was also recognized that an entity was required to coordinate the implementation of a more comprehensive Amphibian Conservation Action Plan (ACAP). The ASG was formed to take on this roll. The ASG is Co-Chaired by Claude Gascon and Jim Collins and consists of a Global Network of some 600 partners. The ASG is responsible for keeping the GAA current to prioritize and support projects around the world to protect critical amphibian habitats. Various funding schemes are also offered for conservation. ASG publications include the Amphibian Conservation Action Plan (ACAP) and a bimonthly newsletter, Froglog. The ASG is building on the ACAP by catalyzing National and Regional Action Plans to advance amphibian conservation. If you are interested in becoming a member of the ASG, please contact the appropriate Chair for the Region in which you work, or contact us with any questions

You can download there publications and read up on how they are saving frogs and other species. They have a frog log which is like a newletter letting you know what there new projects are and how they are helping to slow down and stop the declining number of frogs.

Publications

Overall its an A++ website, thought you and others may enjoy.

reply to post by TheMythLives


I am familiar, actually. But thank you for posting it here, I would not have thought to.

These rapid assessment programs are ideally what I would like to do as a career. They're a critical part to our understanding of the global ecological conditions. And I would be so happy if I could census as a part of these programs...

(If anyone out there has an internship offer... you know...)

In all honesty though. That's my ideal career goal. Rapid assessment programs.

I was thinking, (I do that a lot,lol) is it not possible that some of these vanishing species are just becoming extinct due to natural selection?

reply to post by jkrog08


You ask good questions.

Basically, no. Although many right-wingers will tell you otherwise.

But scientifically, the decline is happening far too quickly. And in this case, things like deforestation and pollution are happening. Habitats are being destroyed, we know this. Frogs are showing up with mutations that are not natural, that can be reproduced when frogs are introduced to specific hormones or chemicals or parasites.

These species have been around for much longer than we have. I mean, in a way, you could say yes: that humans are the strongest so we are wiping out weaker species. Natural selection.

But we're kind of dumb and careless. We can't survive in the same habitats and conditions that amphibians can. They've had no trouble surviving until we got around.

Now we're getting rid of them too fast for them to be able to evolve to withstand these changes. They can't evolve quickly enough to develop more resistant skin or organs, or to find a way to live when their habitats are destroyed.

They wouldn't naturally be dying out like this. Not without human impact, be it cutting down trees or pollution or chemicals or pesticides or anything.

Even with the parasites... why are the parasites a problem? Because the humans have done things to the environment, such as pollution, to allow the parasites to become stronger and the amphibians to become weaker.

So generally no. But people will always say yes because they can't believe this is all our fault.

Take a quick sec and think about how the world would look without humans having ever been here.

...Right.

You will pleased to know that we failed to cover our pool last fall and of course it was full of tadpoles that have now become frogs and you can not stand to be outside in the backyard at night right now for the relentless croaking! I love frogs and am happy to have them, but man they are certainly noisy little critters!

reply to post by Greenize


Awww haha are they american bullfrogs? Do you know? Those are usually what get into the pools around here.

We have a swamp at the end of our road and it's FILLED with spring peepers. They are so loud, but sound so pretty at the same time.

reply to post by ravenshadow13


I know they are not bullfrogs, those get in the little pond in my water garden out front and get rather large, these are small frogs that tend to blend with whatever surface they are on. They can be green and I have seen them on the rim of the pool which is white and they lighten to blend. They are clingy if they get on you too. I pick them up sometimes and pet them...lol They climb on the house and cling to the siding...they are rather cute little things. I will see tomorrow if I can get a pic and post it for you.

reply to post by Greenize


That would make me so happy!!!
You could also try describing their call. If it's more of a chirp, it might be a peeper. They're pretty common. I used to have a few as pets when I was little (we're talking really little here, haha) Description sounds like that.

www.amomentonearth.com...

Your basic spring peeper, Pseudacris crucifer.

[edit on 6/1/2009 by ravenshadow13]

Thanks so much for such an interesting and informative thread Ravenshadow! That link on the unusual frogs was fascinating!! I had no idea there were such strange looking frogs. LOL

Greenize, your frogs sound like a grey tree frog. I had one as a pet once. Sometimes it was like an army green, other times a whitish grey.

As to why their dying ?? who knows, nature seems so fragile sometimes, ... it could be a toxin that is being absorbed by an animal, which in turn gets absorbed by a mosquito which is eaten by ..... then so on, and so on.

But some animals naturaly go exctinct, ... after all, arent 99% of all the species that have ever existed already exctinct ?? I just hope man is playing a minimal part in this case.

Lord knows I love frogs, ....... barbecued, roasted, saute'd .... delicious.

[edit on 29-7-2009 by IntastellaBurst]

There is a very nasty fungal disease that Frogs and other amphibians are falling victim to at the moment, called Chytridiomycosis.


en.wikipedia.org...


From the Link:

Chytridiomycosis is an infectious disease of amphibians, caused by the chytrid Batrachochytrium dendrobatidis, a non-hyphal zoosporic fungus. Chytridiomycosis has been linked to dramatic population declines or even extinctions of amphibian species in western North America, Central America, South America, eastern Australia, and Dominica and Montserrat in the Caribbean. The fungus is capable of causing sporadic deaths in some amphibian populations and 100% mortality in others. There is no effective measure for control of the disease in wild populations. The disease is contributing to a worldwide decline in amphibian populations, a worldwide decline of species that apparently has affected 30% of the amphibian species of the world.[1].

Chytridiomycosis is believed to adhere to the following course: zoospores first encounter amphibian skin and quickly give rise to sporangia, which produce new zoospores [4]. The disease then progresses as these new zoospores reinfect the host. Morphological changes of amphibians infected with the fungus include a reddening of the ventral skin, convulsions with extension of hind limbs, accumulations of sloughed skin over the body, sloughing of the superficial epidermis of the feet and other areas, slight roughening of the surface with minute skin tags, and occasional small ulcers or hemorrhage. Behavioral changes can include lethargy, a failure to seek shelter, a failure to flee, a loss of righting reflex, and abnormal posture (i.e. sitting with the hind legs away from the body)

In short, the disease means the skin of the amphibian can not breathe and remain moist, and suffers from wounds that inhibit movement and creates ulcers and bleeding.


Together with Habitat loss, (at Man's hand) pollution, and climate change, amphibians, like all animals, are facing several factors that contribute to making their lives harder.


en.wikipedia.org...


This year in my pond we had an abundance of tadpoles. Then they started dying. Not from predation, but just floating to the top and dying.


Then it stopped, and we had several surving tadpoles.


We've only seen one or two froglets out of all the tadpoles we had, together with the two resident adult frogs. Now tadpoles suffer from natural predation, but with all the other problems they are facing....if my pond is just a microcosm of what is happening nationwide, or globally....we could see a population crash that is quite devasting.




[edit on 29-7-2009 by Regensturm]

[edit on 29-7-2009 by Regensturm]

reply to post by Regensturm


I'm sorry to hear about your pond, but glad that it is doing better.

I did mention the Chytrid fungus in my OP. I think that is probably a big part of the problem. It's been found to cause so much damage in so many areas of the globe... unfortunately, there are already signs of a vast irreversible population crash.

There are agencies trying to quarantine and treat individuals of populations which have tested positive for Chytrid. In "The Thin Green Line" which I linked to in my OP, too, they talk about a couple in the rainforest which are treating with bleach, and the frogs are responding really well to it. So when the area is free of the fungus, over time, they can release the now clean frogs.

I hope it works. We've already lost so many species, and that probably includes ones that zoologists never got a chance to name.