Wednesday November 18, 2015

Male Pupfish
Some fish can put up with a lot. And few species highlight the extraordinary adaptability of fishes than those that live in extreme environments, such as dry deserts. We’ve written previously about the Devils Hole pupfish, a single population teetering on the brink of extinction in a single pool in Death Valley, one of the most inhospitable environments in the world (see Fish in Unlikely Places). With the 47th meeting of the Desert Fishes Council kicking off today in Death Valley National Park, we thought it was a fitting time to highlight another remarkable desert dweller: the Salt Creek pupfish (Cyprinodon salinus).
Salt Creek
These relatives of the Devils Hole pupfish have their own extremes to contend with. They inhabit Salt Creek, a seasonal stream that dries up to a mere 1.5 km stretch during parts of the year. The spring that feeds the creek forms pools where the fish can hunker down when the rest of the river runs dry. The fish’s habitat expands when rains fall and swell the size of the creek. The creek gets its saltiness from the continual evaporation of its shallow water, which concentrates its salts. The salinity of the creek can reach 35 parts per thousands, which is as salty as seawater. The temperature of this desert habitat also swings dramatically throughout the year, from near freezing to 40ºC (104ºF).
Group of pupfish
The ichthyologist and naturalist Carl Hubbs coined the term “pupfish” to describe the fishes’ seemingly playful behavior. When one of our biologists visited Salt Creek in April this year, the resident pupfish were living up to their name during the height of their breeding season. While the fish can reproduce year round, the most frenzied action occurs in the spring. They zipped up and down the shallow creek in a frantic tumble, bent on a quest to feed and reproduce. The tan colored female fish blended in with the sandy creek bottom, while the flashier males stood out more prominently in their breeding colors of yellow, purple and blue. The fish feed on algae and debris along the creek bottom, often digging into it like puppies. Life is short for a Salt Creek pupfish, just one year or less. With time of the essence, it makes sense that the little fish are constantly on the move.
Female pupfish
While the dryness of the desert would seem to pose the largest threat to a water-dwelling fish, rain can be damaging as well. Large rains and floods can wash fish into pools or side channels that eventually dry up. In October, storms and flash floods tore through Death Valley, dumping debris into Devils Hole and likely wreaking havoc on the Salt Creek pupfish population as well. With the coming El Niño predicted to bring more of these downpours, let’s hope the pupfish are able to weather yet another kind of extreme.

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