Scholar speaks on the study of climate change

Allegheny College Environmental Science/Studies Department hosted Amanda DelVecchia, a postdoctoral scholar working at Allegheny through a National Science Foundation grant, on Friday, March 3 as the third installment of the Environmental Science Speaker Series.

Awarded in April 2016 to Professor of Biology and Environmental Science Scott Wissinger, the NSF grant provides Allegheny students summer opportunities to work with Wissinger and collaborators from North Carolina State University and the University of Maine. Research and data collection for this project take place in pond and wetland ecosystems near the Rocky Mountain Biological Laboratory in Colorado.

What I would like to demonstrate … is how we actually put together projects that answer questions that will be informative about ecosystem services.

— Amanda DelVecchia, Postdoctoral Scholar

After applying for the postdoctoral position under the grant, DelVecchia began work on the project in Colorado in June 2016. She presented “Understanding Baseline Ecosystem Function in a Changing Climate: Case Studies from Two Montane Aquatic Ecosystems,” which discussed the project in Colorado as well as a similar project in Montana.

“There are words that we throw around a lot, like productivity and carbon cycling, but the way that you actually study those things and the individual pieces of data that come together for global predictions are a little more fuzzy,” DelVecchia said.

The case studies she presented were based on relationships and potential relationships between climate change and the freshwater ecosystems of the regions.

She addressed these relationships and understandings by describing her doctoral work with the University of Montana in the Nyack floodplain and other flood plains in Montana and Washington state.

This study first focused on the Flathead River in the Nyack aquifer, a river that is characterized as expansive and nearly-pristine, similar to French Creek, she said.

DelVecchia described the aquifer as an oligotrophic system, which is a system that is nutrient-poor and oxygen-rich.

“So this is essentially a really barren, dark environment,” DelVecchia said. “There’s really no photosynthetic food sources in here, and it’s a really hard place to survive.”

DelVecchia said that despite these characteristics, tens of thousands of stoneflies live in the sediments of the floodplain, which are relatively large organisms to be living in such sediments.

“There’s no visible base to the food web, yet we have abundant consumers,” DelVecchia said. “There’s clearly some carbon source moving into this system that we didn’t yet understand.”

Using carbon isotope signatures, she determined that the stoneflies were sourcing their carbon from methane, an important greenhouse gas. This information provoked new questions for DelVecchia, such as when the carbon in the methane was first isolated from the atmosphere.

This moment in the study highlights the compounding nature of research — one question could yield a discovery, but a discovery often leads to several more questions.

In this case, DelVecchia addressed the questions by expanding the research. Seven sites in the Nyack floodplain as well as sites in other Montana floodplains and a Washington state floodplain were studied with respect to the methane concentrations at those sites, the age of carbon in the methane and how the methane moves through the food web.

“The data told us that for the most part, productivity in these pristine systems is maintained by carbon cycling through methane production,” DelVecchia said.  “Across all these other different floodplains, we still see a high contribution of methane-derived carbon to consumer biomass.”

DelVecchia concluded the discussion of this first case study by noting the significance of carbon from methane being present in the biomass of stoneflies. She said that the conversion of methane in these systems to biomass is better for the ecosystem than if the methane remained as methane.

She then discussed her postdoctoral research in Colorado and the fact that it requires a different set of considerations because, unlike the fairly stable areas of study in Montana that have been more resistant to impacts of climate change, the areas surrounding the Rocky Mountain Biological Laboratory have already experienced alterations because of climate change.

DelVecchia said different considerations include gradients of elevation and gradients of pond impermanence.

Areas at high elevations tend to be more affected by climate change than areas at low elevations, she said. The ponds at these high elevations in Colorado are classified based on how often they dry out. DelVecchia described these classifications as permanent ponds that are wet every year, semi-permanent ponds that will dry out some years and temporary ponds that will dry out every year.

“Data specifically from the Rocky Mountain Biological Station area show that snowmelt dates have shifted two to three weeks earlier over the past 29 years and winter air temperatures have increased by almost a degree per decade,” DelVecchia said. “This is a pretty drastic change, so you would expect that maybe those permanent ponds aren’t going to be so permanent anymore.”

For Colorado, caddisflies serve as the species of study for how those changes might impact ecosystem function, according to DelVecchia.

The collaborative Colorado research will continue this summer.

These cases are two of many ways to study the effects of climate change on ecosystem function, DelVecchia said.

“Each of those approaches, even though they’re in these two distinct ecosystems, provides us with an ecological understanding of global carbon feedbacks,” DelVecchia said.

Alexandrea Rice, ’17, a current student of DelVecchia’s, connected the talk to her own experiences at the Woods Hole Marine Biological Laboratory in Massachusetts.

Rice spent fall 2015 at Woods Hole exploring the concepts on which DelVecchia presented. Rice studied nutrient cycling — particularly the cycling of nitrogen — to better understand nutrient movement through ecosystems.

“The point of looking at food webs, and the whole point of our studies, was to make this flow chart of primary productivity and nutrient cycling,” Rice said.

Having the opportunity to apply classroom learning to field learning like Rice did is important for developing a deeper understanding of science and a deeper understanding of what it means to be a scholar post-graduation, according to Wissinger.

“I think what having a postdoctoral associate here who’s interested in teaching does is that it brings another level of expertise — it brings a new resource for existing students,” Wissinger said.