UC Davis Stable Isotope Lab houses climate reconstruction of the past

Due to recent unpredictable weather, students have to face the tough decision of whether or not to lug a jacket around campus all day in case it suddenly rains or gets cold. Surprisingly more accurate than our current everyday weather predictions are climate conditions of the past.

Scientists can determine what the climate was like in the month of August 100,000 years ago or what ocean temperatures were 30 million years ago.

These incredibly detailed reconstructions of past climate information occur at the UC Davis Stable Isotope Laboratory (SIL) in the Department of Earth and Planetary Sciences.

One research method at the SIL includes using a highly specific laser to shave off miniscule particles of a fossil material in order to analyze its composition and determine the type of environment it was in.

Daily sampling through laser analysis is used on coral because it grows so quickly. Essentially, information can be gained on what coral did on a day-to-day basis all the way back to 100,000 years ago.

“We are very interested in the ocean temperature of the arctic right now, and looking at data regarding how arctic sea ice melted over last 10,000 years and when the arctic was ice free,” said Howard Spero, professor in the Department of Earth and Planetary Sciences and the director of the SIL.

Additional research includes looking at the effects of ocean acidification in the past and present.

Inquiries into developing and calibrating new geochemical tools to reconstruct past environments also occur at this lab. Researchers seek to extract novel climate information from the geologic record.

The research lab in the Department of Earth and Planetary Sciences was founded in 1993 and will celebrate 25 years of research next year.

The goal of the lab is to have the analytic capabilities to measure carbon, oxygen, hydrogen and nitrogen isotope ratios on collected fossil material.

Through analysis of rocks and deep sea sediments, scientists are able to reconstruct the environment from when the organism was alive.

“We do a lot of research and collaborations with graduate students and researchers all over the world interested in looking at records of environmental change through changes in stable isotope geochemistry contained within skeletons, shells and minerals,” Spero said.

Types of samples that are often analyzed at the lab include: microfossils; corals; foraminifera, or sand-sized marine protists; diatoms, a type of phytoplankton; and radiolaria, tiny protozoa, or single-celled organisms.

When these organisms die, the remains and shells accumulate on the seafloor and become part of the sediment. Over time, more layers of sediment build up on top.

Scientists are able to deduce the age of sample sediments collected based on the composition and how deeply buried the layer is. A sample collected near the top of the seafloor will be younger than a sample taken at a meter into the seafloor.

“Trace amounts of other elements are incorporated into a shell when [an organism like foraminifera] grows,” said Jennifer Fehrenbacher, former post-doctorate and research scientist at the SIL via email. “The composition of the trace elements varies with growth conditions like temperature and pH. This makes them useful as ‘proxies’ for environmental conditions in the past.”

Extremely precise lasers and probes enable analysis of collected samples. Housed in this lab is an inductively coupled plasma mass spectrometer (ICPMS). This machine fires laser at a sample to ablate, or remove thin layers, of about 100 nanometers. To give some context, a dime is approximately 1 millimeter thick, and fits 1 million nanometers.

“The laser is an amazing analytical tool because it is minimally destructive so you don’t consume the entire specimen during analysis,” Fehrenbacher said via email. “That means that you can quantify the elemental composition of the specimen you are studying using the laser and the remaining part of the specimen can be analyzed using other instruments.”

The shaved off surface sample material goes into a mass spectrometer that then gives information about the stable isotopic composition.

Tessa Hill, an associate professor in the Department of Earth and Planetary Sciences and a researcher at the SIL, seeks to understand climate change impacts on the ocean in the past and present. By studying the chemistry of the shells of foraminifera, clues can be given to how the environments have changed in the past.

“In this project, we are interested in whether the chemical fingerprint of the shells (elements like Mg [Magnesium] and Ca [Calcium]) changes under particular future climate scenarios,” Hill said via email. “So, we raised foraminifera in the lab, under controlled temperature and water chemistry, and then we analyzed the shells in the Stable Isotope Lab.”

Hill, along with student researchers, utilized the ICPMS to remove a thin layer of the shell to determine its composition.

There are currently two stable isotope labs on campus which each serve a different function.

“The SIL is purely a research lab that conducts and analyzes primarily different types of calcium carbonate, silica and water samples for reconstructing climate history, as well as environmental change on earth today,” Spero said.

The second lab is a service lab, called the Stable Isotope Facility in the Plant Sciences Department. This lab accepts samples to analyze from researchers both on campus and worldwide.

Once analyzed, the lab sends the data back, and no longer takes part in that research. This facility has a far larger range of analytical capabilities with hundreds of thousands of organic and water samples cycling through.

The SIL collaborates with many institutions, and encourages graduate and undergraduate students who are able to operate instruments in the lab to collect data for their senior thesis projects.

“UC Davis gives students the opportunity to work with world-class researchers in their labs and learn techniques that will propel [their] career in the future,” Spero said. “Take advantage of this because if not, you are missing out on an incredible opportunity.”

Written by Shivani Kamal — science@theaggie.org

Biodiversity Museum Day showcases nematodes, yeast cultures, wildlife conservation

The UC Davis campus swarmed with guests of all ages on Feb. 19 as they examined the cutting-edge research done at the university. Among the research displayed were collections of nematodes, fish biology and yeast and wildlife.

The small but mighty nematode fanfare at the Biodiversity Museum Day featured a dynamic microscope in which visitors could see the small worms up close, as well as several jars full of nematodes relevant to daily life, such as a preserved dog heart in a jar with heartworms, a species of nematode, and also a preserved peach root that had root-knot nematodes, one of the organisms most economically damaging to agriculture.

According to Chris Pagan, Ph.D. student in the Department of Entomology and Nematology graduate group at UC Davis, nematodes make up about 80 percent of all multicellular animals on earth.

“Most people don’t know they exist, and not many species have been described,” Pagan said. “Only about 27,000 species of nematodes have been described […] [Nematodes] are everywhere life exists, obviously they are doing something and we’ve just begun the scratch the surface of that.”

The two small table displays generated a big crowd when they opened; children flocked to the microscopes and examined jars of nematodes eagerly. Pagan stressed that events like Biodiversity Museum Day are important to science but also important to generate “nematode appreciation.”

“These [events] are really gateways to science […] and generating interest in science in general,” Pagan said.

The Phaff Yeast Culture Collection had a two-room exhibition complete with microscopes and taste tests. There were several tables with displays explaining the institute’s research and its yeast collection. Kyria Boundy Mills, the curator of the Phaff Yeast Culture Collection, has been with the collection since 1998.

Mills maintains over 800 different species of yeast. Mills’ job includes sending yeast out to people who are doing research while also conducting her own research and expanding the collection. The Phaff Yeast Culture Collection is one of only four collections in the world that holds this much variety and volume of yeast species.

The research that Mills conducts has led to the discovery of a new kind of glycolipid, a molecule that contains a sugar component and a fat component.

“We’ve got some publications on the structure of these weird glycolipids,” Mills said “It’s a new class of molecules. Working with the metabolomic center, we were able to identify the chemical structure.”

According to Mills, the molecule’s nature makes it a natural detergent that is both biodegradable and environmentally friendly.

The Museum of Wildlife and Fish showed off an impressive collection of the animal kingdom. The display included primate skulls, touchable reptiles, a lion skin and bird dissections. The museum holds 55,000 vertebrates and is one of campus’ “best kept secrets,” according to Andrew Engilis, the museum’s curator.

Research done at the museum includes projects such as the Putah Creek Nestbox Highway, which involves setting up nest boxes for cavernous nesting birds while a team monitors them.

“The museum is very dynamic: it’s not just specimens in drawers and cases; it’s the focal point for teaching in our department,” Engilis said. “The specimens are a way for the students to connect to the natural world from the textbook.”

Nematodes, yeast cultures and wildlife conservation are just a small portion of what Biodiversity Museum Day had to offer.

“[Events like Biodiversity Museum Day] pave the way for a brighter future for our collections here on campus and across this campus our some of California’s most important collections,” Engilis said.
Written by: Emma Askea — science@theaggie.org