Dr. Hillyard Continues 40-plus-year Research During Retirement

Stanley Hillyard, Ph.D.
Jun. 20, 2019

When Stanley Hillyard mentions retirement and fish, you’ll likely get the wrong idea.

Hillyard plans to retire June 30 after a 43-year career at UNLV with the last 13 teaching at the School of Dental Medicine. But instead of dropping lures in a placid, backwoods lake to catch bass or trout, he will continue studying and monitoring the population and health of one of the world’s rarest fish, the Devil’s Hole pupfish, Cyprinodon diabolis.

The Devil’s Hole pupfish measures approximately an inch in length and, as a species, may have existed for thousands of years in Devils Hole, a geothermal aquifer-fed pool that descends farther than 400 feet and maintains a temperature of 93 degrees.

When Hillyard came to UNLV’s College of Sciences, the department chair James Deacon introduced him to the diminutive, blue-colored fish.

“Growing up near California beaches, I developed an interest in scuba diving and eventually earned SCUBA certification,” Hillyard said. “James (Deacon) learned about my scuba experience and added me to the dive team, which counts the fish twice each year. Since 1976 I’ve seen (and counted) populations of more than 500 and as few as 35.”

Hillyard retired from diving during 2018, but remains part of the research team. He said the latest census reported 136 individuals. In addition to recording the pupfish’s population numbers, his research includes studying the physiology of desert pupfish. As for his retirement, Hillyard said he has projects he wants to complete, one of which could have implications at the dental school.

“Oxygen levels in Devil’s Hole are so low, we continually wonder how the fish are able to survive. So, one of my projects will be measuring the pupfish’s oxygen consumption,” Hillyard said. “I’ll also be examining how fin development is temperature dependent and what signaling molecules are involved.

“From a dental school perspective, many of the signaling molecules, such as bone morphogenetic proteins, that affect fin development in fish also affect craniofacial development in humans. If we can better understand how this process can be affected by environmental exposure among the fish, we can gain insight into how stresses during human development can result in craniofacial anomalies.”

The Devil’s Hole pupfish, which are a protected, critically-endangered species, as well as the census work and research conducted by Hillyard and scientists from the National Park Service, have been featured on the Discovery Channel, Natural Geographic, and recently by the National Parks Service in its “Underwater Wonders” video series.

Devil’s Hole and other pupfish habitats are located in Ash Meadows National Wildlife Refuge, which is west of Pahrump. A modern visitor center gives the public a perspective into the lure of desert animals including pupfish.