Part One: The Sixth Extinction
|Photo I took of Pacific Tree Frog that appeared in the LA Times|
The first clue to the mysterious killer that was claiming frogs from Queensland to California came— perhaps ironically , perhaps not— from a zoo. The National Zoo, in Washington , D.C., had been successfully raising blue poison-dart frogs, which are native to Suriname, through many generations. Then, more or less from one day to the next, the zoo’s tank-bred frogs started dropping. A veterinary pathologist at the zoo took some samples from the dead frogs and ran them through an electron scanning microscope. He found a strange microorganism on the animals’ skin, which he eventually identified as a fungus belonging to a group known as chytrids. Chytrid fungi are nearly ubiquitous; they can be found at the tops of trees and also deep underground. This particular species, though, had never been seen before; indeed, it was so unusual that an entire genus had to be created to accommodate it. It was named Batrachochytrium dendrobatidis— batrachos is Greek for “frog”— or Bd for short. The veterinary pathologist sent samples from infected frogs at the National Zoo to a mycologist at the University of Maine. The mycologist grew cultures of the fungus and then sent some of them back to Washington. When healthy blue poison-dart frogs were exposed to the lab-raised Bd, they sickened. Within three weeks, they were dead. Subsequent research showed that Bd interferes with frogs’ ability to take up critical electrolytes through their skin. This causes them to suffer what is, in effect, a heart attack. Kolbert, Elizabeth (2014-02-11). The Sixth Extinction: An Unnatural History (Kindle Locations 198-209). Henry Holt and Co.. Kindle Edition.As it turns out one explanation of the spread is the wide scale importation around the world of North American Bull Frogs (for food) and the African Clawed Frog (used for pregnancy tests). Both carry but are resistant to the fungus and their spread would not have been possible without air transport.
I have personally witnessed this 6th extinction. Just 5 or 6 years ago the Pacific Tree Frog was common here on the West Coast. Their chirping or croaking was a way of life. If you were unfortunate enough to have one outside your bedroom window in the summer you probably wouldn't get a very good nights sleep. Three or four years ago they simply disappeared. The North American Bull Frog was not indigenous to this area but had been introduced several years ago - a possible explanation.
There are many similar examples. The introduction of the European earth worm nearly destroyed the North Eastern hardwood forests before the Revolutionary war is is still causing problems in the entire northern half of the United States. The Fox and Eastern Gray squirrels are spreading across the country from the North East probably hitching rides on trucks and trains. The result is the Western Gray squirrel is threatened. When debris from the earthquake and tsunami in Japan started washing ashore here on the west coast the major concern was not radiation but invasive species.
I guess the question is can human beings survive the 6th extinction they are responsible for?
|Pacific Tree Frog|
Part Two:The Anthropocene
There is widespread agreement that we are in a new geological era, the Anthropocene. I just finished The Sixth Extinction: An Unnatural History and it is all about the Anthropocene. There are some who think this era started when man began to use fossil fuels a few hundred years ago but they are wrong. Homo Sapiens and yes even Neanderthals altered the world tens of thousands of years ago. The extinction of large mammals can be associated with human migration. Being large was a survival advantage until smart hunters came along. We were also responsible for the extinction of our retaliative, the Neanderthal, but not before we had had enough sex with them to leave all of us of with European or middle eastern descent with 3 to 6 percent Neanderthal genes. It's estimated that up to 90% of the Native American population was killed not by European weapons but European diseases.
Human caused global climate change may only be the most important because it may result in man's own extinction. There have been shifts in the climate of the planet before but the thing that makes this different is the speed it's occurring. The ocean is dying, because of acidification the corral reefs will all be dead by 2050. The combination of entire ocean ecosystems dying and over fishing will result in the starvation of millions and perhaps billions who depend on the sea for food. It is also estimated that up to 50% of all species on earth in 1900 will be extinct by 2050. While it's easy to blame the Koch brothers and Exon/Mobile how many of us are willing to give up our energy intensive life style? This post has been written from both my desktop and laptop computers. I have a large screen TV and I stream movies and TV shows. I don't drive or own a car but this is because of vision problems and I probably would if I could. So I plead guilty, I'm part of the problem.