Earthquake may lead to an increase in pupfish numbers

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Although earthquakes are usually associated in with massive disruption and destruction for humans, the Devil's Hole Pupfish may have been pulled back from extinction thanks to seismic activity.

It's listed as an endangered species and numbers have fallen as low as 38 individuals over the last 5 years. Following a recent earthquake though, researchers have noticed a significant increase in the number of fish as well as evidence that fish were spawning.

Situated in the Death Valley National Park, Nevada, Devil's Hole offers possibly one of the most inhospitable aquatic environments on the planet. Water temperatures average around 33C and fish are confined to a tiny area within the cavern - "the smallest habitat of a vertebrate species" according to Scott Bonar, a member of the pupfish population recovery programme.

The species' entire home range amounts to a shallowly submerged limestone shelf around 2m wide and 4m long, upon which the pupfish has adapted to mature, feed, and spawn. The population is closely monitored by staff from the University of Arizona (UA), and it is their video footage that has provided an insight into the how the species reacted during the tremors.

The UA team film the fish on a regular basis, with cameras positioned above and below the water surface to monitor spawning behaviour and caught the earthquake on their observation cameras.  "The water was sloshing back and forth so hard it splashed against our cameras" said Ambre Chaudoin from the U.S. Geological Survey Arizona Cooperative Fish and Wildlife Research Unit at the UA. "The quake swept the shelf clean from algae, shuffling the silt and cobble around. Such disturbance can be important because the spawning shelf is...smaller than many walk-in closets."

The sudden shake-up seems to have had a positive effect on the vulnerable population though, with a small increase seen in fish larvae numbers following the quake. As Paul Barrett, leader of the Devil's Hole Pupfish Recovery team explains, "Quakes can serve a useful purpose in shaking silt and other fine particles that have washed into Devil's Hole off of the spawning shelf and into the deeper waters. This frees important space between the substrate particles where the Devil's Hole pupfish larvae seek refuge."

The research team at UA remain cautious about the plight of the pupfish – numbers are still incredibly low – and are intrigued by the possible role of environmental disturbance in promoting spawning behaviour. And Chaudin is now dedicating all her time to finding out more: "There is a possibility they might like disturbance - perhaps the video recordings will reveal something . I'm going to spend all my nightlife watching hours and hours of video and extracting data from it!"