The Forks National Historic Site

   Amphibians have been around for an estimated 350 million years, surviving the many harsh changes that eliminated so many other species of organisms during the time. But throughout the past few decades, the species has seemed to have declined with 170 species thought to have gone extinct. Today there is an estimated number of 7,000 known species of amphibians in the world and an estimated one-third are threatened with extinction. A recent study by the U.S geological survey found that just the US amphibians have been vanishing at an average of 3.7% each year meaning they could be gone from half their current habitats by the next 20 years. 

   One reason why amphibians are on their way to total extinction is that bodies of water where frogs reproduce are delicate ecosystems and the proper amount of balance is needed for everything to survive. Things such as algae can really cause distress amongst the balance in the water because it can either reduce or completely eliminate the oxygen in the water. With a lack of water, fish can become very ill and/or die off. The water could then reach a point where it becomes so vile that anybody who comes in contact with drinking or eating the remaining fish from the water could also succumb to illness and also possibly die off. The same thing could also happen to tadpoles which leads to them dying off at a young age where they still can't mature and help the ecosystem that they are residing by being able to absorb toxic chemicals, radiation, and diseases. 

   Reasons for the species extinction are caused by things such as pesticides heavy metals and acid rain as well as mounting habitat loss, studies also show that amphibians are steadily declining also due to things such as disease. Specifically, the infectious fatal disease is known as Chytridiomycosis which is caused by the aquatic fungus known as Batrachochytrium dendrobatidis (Bd). Though whereabouts of where the fungus originated remain unknown, researchers have detected traces of Bd preserved in specimens from African Clawed Frogs dating back to 1938. This was also around the when these frogs were being shipped around the world to be used for things such as pregnancy tests so that concludes that one theory believes that they are the source.

   Scientists recently sequenced the genomes of nearly 30 Bd strains from around the world and in doing so have realized the evolutionary history of the fungus is more complex then they originally thought, so that concludes that more research is still needed before the display of a concrete answer regarding its origin. 

   In the last three decades, Bd has caused the infection of at least 350 species, many of which are now extinct in what may be the greatest disease caused biodiversity killer in recorded history.

   The disease works by infecting the amphibians superficial skin layers that contain the protein keratin this then leads to a thickening or hyperkeratosis and increased sloughing or shedding of the skin.

   One of the most vital organs for an amphibian would be its skin. Its thin and permeable and involved hydration thermal regulation and respiration. This species also breathe through their skin also while absorbing vital electro-lights like sodium magnesium and potassium. But when Bd interferes with the absorption it can cause nutrient deficiencies which can ultimately lead to death by cardiac arrest if the infection hasn't already made the animals so weak that it either starves or eaten. 

   

   Cases Bd has been found in everywhere except in Antartica where there are no amphibians there, to begin with.

   

  Scientists are still unsure on how this fungus moves through an environment on its own but evidence shows that it gets a lot of inadvertent help from us humans mainly through International Amphibian trade for uses such as exotic pets or for human consumption. Climate change could also be a factor in aiding the spread of Bd through warming temperatures, extended droughts and general changes in the time and amount of precipitation will affect the life cycle of amphibians all throughout the world. Plus, as temperatures warm many plants and animal species shift their ranges to higher elevations. Infected amphibians migrating to these new territories are bound to bring the disease with them and in hence, infect new populations. 

   The pathogenic fungus, Batrachochytrium dendrobatidis (Bd), causes chytridiomycosis (also known as chytrid fungus disease, which kills amphibians by destroying their skin, disrupting their immune systems, and causing heart failure). Scientists first recognized its lethal effects in the 1990s when numerous species of frogs in Australia and Central and South America experienced massive die-offs; a related fungus attacks salamanders. Bd has been blamed for the extinction of hundreds of amphibian species and poses a threat to up to one-third of the world's frogs, salamanders, and other amphibians. There is no cure, but some frog species infected with the fungus are able to survive for years, indicating that they've adapted to the disease. Indeed, a recent study showed that Bd has been evolving with amphibians for some 40,000 years, although some species have only recently encountered it.