Sunday, February 14, 2010

The Last Animal Anyone Expects to Find: The Rarest Creature in Death Valley

Looking over the blasted barren rocks of Death Valley National Park, one is struck by the apparent lack of life. A region that averages less than two inches of rain in a year, with summer temperatures regularly topping 120 degrees, is just not going to have a lot of moisture left over to support life. and yet life persists, and sometimes in incredible ways. Hundreds of species are found in the region, including dozens of endemic and endangered species.

What is the last kind of animal you would ever expect to find in a place like Death Valley? Here's a candidate: in an outlying part of the park, just over the border in the state of Nevada, there is a barren hillside of carbonate rock (limestone), that has been twisted upwards and fractured. Strolling towards the base of the hill, one notices a cavern opening surrounded by reinforced fencing. It's a deep cave, more than 900 feet, but surprisingly, it is filled with groundwater at a constant temperature of 92 degrees.

Looking through the fence, one can see the small pool of water at the bottom of the narrow cleft. The monitoring equipment is a clue that something extraordinary lives here. It's a fish! And not just any fish, it is probably the rarest fish in the world, the Devil's Hole Pupfish. The species has lived in this little bit of water for the last 20,000 years, when it was isolated here by the drying of the glacial meltwater lakes that punctuated the Death Valley region. Through droughts, climate change, cooling, and in the last few years, interference by human beings, the little community of a few hundred individuals has grown, reproduced and died in this opening.

A few decades ago, as many as 600 fish lived here, but by 2004 the population had crashed to just over two dozen individuals. The population had recovered by 2007 to 126 fish, but their continued existence will always be tenuous. They would have been extinct in the late 1970's had the Supreme Court of the United States not stepped in. It was an early major test of the Endangered Species Act. As can be seen below, major efforts have been expended to monitor the health of the population.

It is not really possible to see the individual fish at Devils Hole, but a much larger and more stable population of a related species can be seen a few short miles away at Ash Meadows. The pool below is Crystal Spring, which produces 2,600 gallons per minute of 87 degree water. The Ash Meadows Pupfish lives in the pond and nearby stream, and is far easier to see, as we did today.

My picture of the Ash Meadows fish didn't come out, so I am slipping a picture of the Salt Creek pupfish from a previous trip. The Salt Creek fish live in the bottom of Death Valley not too far from Furnace Creek Resort.
Four species of pupfish live in various parts of Death Valley, with some living in the hottest and saltiest water of any fish species on the planet. Others live in fresh water. They are all descended from a single species of pupfish that lived in the glacial meltwater lakes of the ice ages. An example of real resilience in the face of difficult conditions!
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