Connectivity in Desert Aquatic Acosystems: The Devils Hole story

Riggs, Alan; Deacon, J.

Devils Hole, a skylight to the water table (and beyond) in one of the harshest North American deserts, is a prime example of how perennial desert waters tend to be at the intersection of aesthetic and cultural appreciation, economic and legal conflict, and scientific study. Devils Hole is a fissure, opened by regional tectonic extension of Paleozoic carbonate rocks, that acts, in concert with innumerable other similarly formed fissures, as a subterranean drainage network that transmits rain water and snowmelt, primarily from the relatively well-watered upper elevations of the Spring Mountains, to arid basin-floor spring discharge oases. The water passing through Devils Hole is supersaturated with calcium carbonate, which has precipitated on its walls in a number of morphologies, each of which precipitated under a unique set of conditions. The distribution and age of the different calcium carbonate morphologies record multiple aspects of the history of Devils Hole and the region, including an indication that Devils Hole opened to the surface about 60,000 years ago. There is also evidence that, probably primarily in response to climate change, the water level in Devils Hole has moved up and down but has had a net downward trend, and has apparently never been high enough to overflow the lip in the last 116,000 years. These historical insights are important to Devils Hole’s best-known inhabitant, the Devils Hole pupfish, because if water never overflowed the lip, there is no apparent way for the pupfish to have colonized the Hole. Beyond that, pupfish life in Devils Hole has built-in problems. The water in Devils Hole is almost too warm for successful pupfish reproduction, and limited dissolved oxygen exacerbates the problem. In addition, the narrow fissure above the Devils Hole pool limits the amount of sunlight available to power primary productivity, and hence the amount of food available to pupfish and the other aquatic biota. Nonetheless, pupfish survived, apparently without problem, until the late 1960s when the Devils Hole water level and the pupfish population began to fall precipitously in response to pumping of nearby irrigation wells. The decline set off a classic values conflict between conservationists, who wanted the pumping stopped to prevent extinction of the fish, and many in the local population interested in the potential economic expansion made possible by development of the ground water resource. The conflict over water rights played out on the national stage and escalated to the U.S. Supreme Court, where it was resolved in favor of the conservationists. So, the pupfish live on but so does the pressure to develop the limited water resources of one of the driest areas of the country.

Connectivity in Desert Aquatic Acosystems: The Devils Hole story

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