Serena Moseman-Valtierra
University of Rhode Island
Assistant professor; biological sciences
SURF program mentor

Sitting at the interface of land and sea, salt marshes serve as the mediator of the marine realm. From one side, the ocean tides flood and drain the coastal wetlands; from the other, land runoff leeches through on its way out to the sea.

Here among the tall reeds of grass, roots anchored in the mud of the salt marsh floor, Serena Moseman-Valtierra studies the cycles in which plants take in and emit greenhouse gases.

“Salt marshes have long been valued for their ability to filter pollutants and nutrients,” says Moseman-Valtierra. “They could help us with climate change by minimizing the extent of the impact — another tool in our toolkit to try to solve or reduce human impacts.”

In an early RI Science and Technology Advisory Council (STAC) collaborative research grant, Moseman-Valtierra worked with Associate Professor Breea Govenar, Rhode Island College (RIC), to investigate whether climate change was switching the role of salt marshes from carbon sinks to sources. The research paired Govenar’s expertise in invertebrates, particularly the mussels and snails that live in the marsh, with Moseman-Valtierra’s in plants and the biogeochemical cycling of nutrients.

For her part, Moseman-Valtierra focused on the impact of nitrogen on greenhouse gas emissions from coastal marshes, measuring the fluxes of the gases; Govenar explored the microbial diets of the invertebrates to gauge their gas emission role in the marsh.

“In natural habitats, pollution and nitrogen enrichment can increase the extent to which plants, soils, and animals emit gases,” Moseman-Valtierra explains. “I’m trying to understand the extent to which the input of nitrogen into Narragansett Bay potentially is fueling the release of climate-driving gases from coastal marshes.”

Understanding whether and how human activities — rising temperatures, burning of fossil fuels, raising livestock, for example — accelerate the emission of greenhouse gases from the ecosystem is particularly important given how salt marshes filter pollutants and take up carbon, qualities that could be enhanced through coastal restoration efforts.

With Ph.D. candidate Elizabeth Brannon, Moseman-Valtierra demonstrated a novel method for measuring greenhouse gases with a new laser-based spectrometer that could analyze three major gases simultaneously. This was one of the first applications of this technology in a coastal environment, Moseman-Valtierra says, and the outcomes have been included in their manuscript that has just been accepted for publication in Limnology and Oceanography: Methods.

Additionally, data from the STAC project helped her and colleagues secure two other grants from the National Oceanic and Atmospheric Administration (NOAA) agency.

Meanwhile, a URI master’s student in her lab, Melanie Garate, and several undergraduates (Heather Chan, Robert Ventura, Alexandra Moen) have been investigating how benthic shellfish may or may not emit nitrous oxide, expanding the focus beyond the salt marsh to look beneath the ocean surface. The research utilizes equipment at the Marine Science Research Facility (MSRF), a Rhode Island EPSCoR core facility.

Oysters have low, if any, emission of nitrous oxide, even if they live in polluted water. Mussels, however, are some of the biggest emitters, particularly under conditions of high physiological stress, which, Moseman-Valtierra says, leads to the thought that pathogens might be involved.

In a successful grant proposal with Rhode Island Sea Grant, Moseman-Valtierra is collaborating with URI Professor and EPSCoR researcher Marta Gomez-Chiarri to test the critical thresholds of warming and/or nitrogren loading that seem to make shellfish susceptible to pathogens or switch them from sinks of nitrous oxide to sources.

“We will be able to test how warmer conditions in the future may impact shellfish health and viability,” Moseman-Valtierra says. “Another consequence of climate change, in addition to stressing shellfish and contributing to pathogen outbreaks, is to potentially change how nitrogen cycling is altered and we will test that for these same shellfish — oysters and mussels.”

Throughout all of her research, Moseman-Valtierra taps into the training opportunities with the RI EPSCoR Summer Undergraduate Research Fellowship (SURF) program. She consistently takes on at least two undergraduate fellows each summer and views them as a vital component of her work, both for the research assistance and rewards of mentoring.

“Our line of research requires a lot of field work and we can’t do that without extra hands,” she explains. “It’s also been an added plus for myself and my grad students to have the chance to be a mentor.

“Mentoring is one of the reasons I wanted an academic career; it’s what I find most rewarding. Mentoring takes a lot of time and effort, but it’s probably one of the more worthwhile things that I do.”

Moseman-Valtierra says the mentoring also is part of her effort to increase climate literacy, something she aims to do through public outreach, including working with shellfishermen as part of a RI Sea Grant project with the Coastal Resources Center and the incorporation of education throughout her research.

Story and photo by Amy Dunkle | RI NSF EPSCoR