Crooaaaak.
Not only is that the seemingly simple sonnet of a toad, but it also provides an accurate description for what's currently happening to toads and other amphibians. Globally, populations - and even entire species - of amphibians are quite literally croaking from existence.
Herpetologists, conservation biologists and even Kermit himself are scared of what the future holds for frogs, toads, salamanders and Caecilians. Scientists are scrambling to survey existing populations while urgently collecting valuable life history data (including diet, habitat requirements, reproductive biology) on virtually thousands of amphibian species in order to tackle what's become known globally as the phenomena of "amphibian decline".
What's causing the decline?
Amphibians inhabit nearly every corner of the globe. Approximately 6300 species exist, with new discoveries on the horizon - if, of course, scientists can catch and describe them in time. According to the IUCN, nearly one-third of the existing species are at risk.
This explains why amphibian enthusiasts and experts everywhere are desperate to get to the bottom of amphibian decline. Scientists now point to mounting, multi-dimensional pressures that include pesticides, global warming and habitat decline and fragmentation. There is hardly a corner of the globe that isn't plagued by these eco-system disrupters, which explains why amphibian decline is a global phenomenon. From Central America to Yosemite, scientists have documented populations in peril.
Pesticides. Scientists have confirmed a link between atrazine (one of the most widely used agricultural pesticides) and the mortality of leopard frogs. Described in Science News as a "toxic double whammy", atrazine enhances living conditions for a parasitic flatworm that causes severe and often fatal infections within larval frogs. If that weren't bad enough, atrazine also reduces the strength of the frog's immune system to fight the often fatal infection these parasites cause. And it even gets worse. When atrazine is paired with a commonly used phosphate fertilizer, the conditions become even more favorable for the parasite. The phosphate enhances the conditions for algae, on which the host of the parasite, a species of aquatic snail, feeds.
Global Warming. Unfortunately, pesticides aren't working alone. Experts claim that global warming is also part of the attack on amphibian populations. Scientists report that ephemeral (seasonal) ponds are drying up sooner, costing the lives of salamanders in Yellowstone. Unfortunately, the salamanders are not alone.
In addition to changing habitat conditions, global warming is also exacerbating the spread of harmful disease and fungi - both of which adversely affect amphibians. Throughout Central America, countless frog populations have fallen victim to the chytrid fungus. After succumbing to the fungus, these valuable herps are no longer a part of the ecosystem. As a result, predator-prey relationships become imbalanced causing detrimental affects on the food chain and insect populations.
Habitat Loss and Fragmentation. Worldwide, one of the most potent threats to biodiversity is habitat loss due to development and agriculture.The primary effect of habitat loss is the removal of individuals or populations from a patch of the destroyed landscape. Habitat fragmentation, an ancillary effect of habitat loss, occurs when the remaining populations are isolated because the links between the habitat patches have been destroyed. This hurts amphibians especially as most populations occur in what population biologists refer to as a metapopulation structure. A metapopulation structure means that the populations exist as an interconnected series of populations within a larger geographic area. This population model expects that populations that are isolated will more likely go extinct than those populations that remain connected. Therefore, experts have established habitat fragmentation is a major player in amphibian decline.
It's time to get herping. What can you do to help fight amphibian decline? Start noticing them. Chances are there are some pretty neat amphibians lurking somewhere not too far from your own backyard. If you've never taken the opportunity, now might be the perfect time to do a bit of "herping". (No, herping does not in any way refer to cavalier encounters that risk unmentionable STDs). Herping refers to the act of hunting down herps (a term that includes amphibians and reptiles) - a favorite pastime of both amateur amphibian enthusiasts and the experts that study them. Herping can help you get to know your local populations of amphibians. Over time, you may be able to clue in to potential stressors or pressures that may be affecting these populations.
And as always, promote sustainable and organic agriculture in order to reduce the demand for conventionally grown crops that take a toll on the environment by using chemical pesticides and fertilizers. Get involved with local government and grass root efforts to oversee land use and development to ensure that it's done with the local biodiversity in mind.
For the latest information on amphibian decline, check out the US Geological Survey's Amphibian Research and Monitoring Initiative.
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