Apr 29, 2019 | Blog, Featured researchers
Josh Sackett, Ph.D., is a postdoctoral researcher with the Division of Hydrologic Sciences at the Desert Research Institute in Las Vegas. Josh specializes in the study of microbes that inhabit Earth’s deep subsurface environments. He grew up in southwestern Colorado, and holds bachelor’s and master’s degrees in Biology from University of Colorado Denver, and a Ph.D. in Biological Sciences from University of Nevada, Las Vegas. Josh has been a member of the DRI community since 2014, when he moved to Las Vegas for a position working in DRI’s Environmental Microbiology Laboratory. In his free time, he enjoys hiking and exploring Mount Charleston and other natural areas around Las Vegas.
What do you do here at DRI?
I am a microbial ecologist and postdoctoral researcher with the Environmental Microbiology Lab at DRI. Some of my graduate work took place out in Amargosa Valley, Nevada, where we were looking for differences in the microbial community between Devils Hole and the Ash Meadows Fish Conservation Facility. We learned that the lack of cyanobacteria in the fish conservation facility may be impacting the survival of the Devils Hole Pupfish, which is critically endangered.
Right now, I am studying microbes such as bacteria and archaea that inhabit Earth’s deep subsurface fluids, which we access primarily through deep wells and mine shafts. We’re looking at the genetic material of these microbes using a technique called single-cell genomics where we isolate individual microbes, sequence their genomes, and learn about their potential role in their environment based on what genes are present.
What do you hope to learn about these deep subsurface organisms?
We’re interested in how organisms live life independent of sunlight. These organisms are usually anaerobic (able to live without oxygen, some requiring the complete absence of oxygen), and they live a different lifestyle than most organisms that you think of. Humans, for example, we breathe oxygen and we metabolize organic carbon; these organisms don’t necessarily do that. So, learning about how these organisms live in the absence of oxygen, sunlight, or in environments where organic carbon is scarce gives us insight into potential for life on other planets where oxygen and dissolved organic carbon are likely limiting or not present at all.
Our research has potential for biotechnological applications as well. Sometimes, organisms that live in unique or austere environments are capable of degrading certain compounds, such as contaminants, or produce enzymes that are of interest to the scientific community.
Josh Sackett, Ph.D., is a postdoctoral researcher with the Division of Hydrologic Sciences at DRI’s campus in Las Vegas.
Where does your research take place?
One of our study sites, called BLM1, is located in Inyo County, near Amargosa Valley, Nevada. It’s a 2,500-foot deep well, which really isn’t all that deep. However, the earth’s crust is actually really thin in this area, so you don’t have to drill very deep to access hot fluids. Because of this, BLM1 serves as a stellar field site for investigating life in the subsurface. We also have a study site located along the Juan De Fuca Ridge, off the coast of Washington State, and we plan to look at microbial activity in sediments and fluids from that environment.
How did you end up here at DRI?
I was born and raised in southwest Colorado, in a little town near Durango. I moved to Denver for my bachelor’s and master’s degrees. After that, I was searching for a laboratory to do my Ph.D. research in, and came across Duane Moser’s lab. I was interested in the plethora of projects he had going on, and I thought I could gain a lot of research experience and exposure to many different topics in his lab.
Initially, I wanted to be a physician. However, I caught the microbiology bug — no pun intended — as an undergraduate student, and I’ve been hooked ever since. I really became interested in it because I’m interested in how microbes influence biogeochemical cycling, or how microbes contribute to earth’s processes, on a global scale.
Mar 20, 2018 | News releases, Research findings
Above: Researchers Joshua Sackett (left) and Duane Moser (right) of DRI help National Park Service officials move scaffolding infrastructure during a routine sampling visit to Devils Hole on December 13, 2014. Credit: Jonathan Eisen.
DRI study finds key differences between artificial habitat and the real Devils Hole
Las Vegas, NV (Tuesday, March 20, 2018): In a first-of-its kind study of comparing the microbiology of Devils Hole with that of a constructed scale replica at the Ash Meadows Fish Conservation Facility (AMFCF), a team of scientists from the Desert Research Institute (DRI) in Las Vegas discovered key differences in nutrient levels and species composition that may be impacting the ability of the highly endangered Devils Hole Pupfish (Cyprinodon diabolis) to survive in captivity.
“We were interested in taking a closer look at the chemical and biological factors that control productivity at both sites,” said Duane Moser, Ph.D., an associate research professor of microbiology at DRI who has been involved with research at Devils Hole since 2008. “In studying both, we could gain some insights into how well the artificial refuge actually replicates Devils Hole, and in turn, offer recommendations for ways to make the refuge a better habitat for the pupfish.”
Devils Hole Pupfish (population 115 in autumn 2017) are an iridescent blue, one-inch-long pupfish. They are native only to Devils Hole, an isolated water-filled cavern of unknown depth located in a detached unit of Death Valley National Park within the Ash Meadows National Wildlife Refuge in Amargosa Valley, Nevada. Devils Hole is an extreme environment, with water temperatures and dissolved oxygen concentrations near their lethal limits for most fishes.
Since 2013, scientists have been trying to establish a backup population of these endangered fish in a constructed tank at the AMFCF, which is located a short distance west of Devils Hole. Although the facility was designed to match the climate, water chemistry and physical dimensions of an area of shallow shelf habitat in Devils Hole, the pupfish have had only limited success reproducing and surviving in this artificial environment.
In 2015, Moser and a team of researchers from DRI set out to learn if there were other factors that might be impacting the success of these fish. Their new study, published in the March edition of PLOS One, characterizes and compares water chemistry and microbial communities between Devils Hole and the AMFCF.
Although water temperature and dissolved oxygen at the AMFCF are intentionally maintained at values that are slightly lower and higher, respectively, from those of Devils Hole, this work shows that the nutrient balance between the two sites is also very different, with AMFCF being strongly nitrogen limited – about five times lower than that of Devils Hole.
In the microbial communities, which contribute to the distribution and availability of dissolved nutrients in the water and are also a food source for the pupfish, the research team discovered more than 2,000 microbial species from 44 distinct phyla present in the water at Devils Hole. They detected similar levels of species diversity at AMFCF, but found that different bacterial phyla were dominant at each site. These differences may relate to the observed differences in nitrogen concentrations.
“Nitrogen levels have an effect on the types of organisms that you’ll find, and the types of metabolisms that they have,” said Joshua Sackett, a graduate research assistant with the Desert Research Institute and doctoral student in the School of Life Sciences at the University of Nevada, Las Vegas. “We found a lot fewer of at least one major category of primary producers – the cyanobacteria – in the AMFCF compared to Devils Hole, and we think that’s due to differences in nutrient concentration.”
One of the strengths of the comparative power of this study is that the data from each site were gathered on the same day. This study highlights the potential importance of considering water chemistry and microbiology when constructing artificial fish habitats – and the team hopes that the information will provide a valuable contribution to the continued survival of the Devils Hole Pupfish in captivity.
“This work revealed very different microbial populations, which we infer might correspond to large differences in nutrient dynamics between the sites – especially in terms of nitrogen,” Moser said. “Consequently, some relatively modest tweaks in how the refuge is operated could potentially improve the prospects for continued survival of one of Earth’s most imperiled fishes.”
The full version of the study – A comparative study of prokaryotic diversity and physicochemical characteristics of Devils Hole and the Ash Meadows Fish Conservation Facility, a constructed analog – is available online: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0194404
For more information about DRI, visit www.dri.edu
Photo caption: Researchers Joshua Sackett (left) and Duane Moser (right) of DRI help National Park Service officials move scaffolding infrastructure during a routine sampling visit to Devils Hole on December 13, 2014. Credit: Jonathan Eisen.
Additional photos are available upon request.
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The Desert Research Institute (DRI) is a recognized world leader in investigating the effects of natural and human-induced environmental change and advancing technologies aimed at assessing a changing planet. For more than 50 years DRI research faculty, students, and staff have applied scientific understanding to support the effective management of natural resources while meeting Nevada’s needs for economic diversification and science-based educational opportunities. With campuses in Reno and Las Vegas, DRI serves as the non-profit environmental research arm of the Nevada System of Higher Education. For more information, please visit www.dri.edu.
