Tuesday, August 18, 2015

Change in the Delta

Fig.1: An aerial view of the Copper River Delta in Alaska. (Credit: Andrew Morin)

After years of working at the Northwest Fishery Science Center as a project manager, focusing her work on salmon, Carmella Vizza felt she needed a change.

“I decided it was time for me to go back to grad school to be more involved in conducting my own research,” Vizza said.

Vizza, now a student in Dr. Gary Lamberti’s lab at the University of Notre Dame, and researchers from other institutions and agencies spend their summers traveling to Cordova, Alaska, to collect samples on the Copper River Delta to determine how it’s changed over time due to environmental effects. The delta is studied by a group of interdisciplinary researchers from Notre Dame, Oregon State University and Loyola University at Chicago who all work with scientists from the Pacific Northwest Research Station and the Cordova Ranger District of the United States Forest Service, the agency that manages these coastal wetlands. Some of the investigations are focused on the food web and the species that call the delta home. But there are also members of the group looking at glacial melt and sea level rise, what Vizza calls the more “physical aspects of climate change on the delta.”

The uniqueness that is the delta

The Copper River Delta is the largest adjoining wetlands area on the Pacific West Coast of North America, extending across 700,000 acres. Situated between the Gulf of Alaska and the Wrangell and Chugach Mountains, the delta lies in a geologically dynamic region and was shifted in the Great Alaska Earthquake in the mid-1960s. The river itself flows approximately 290 miles.

“It’s obviously a very expansive system,” Vizza said. “And so part of the research … entails trying to find out what these ecosystems are doing and how they might change with environmental change.”

But, because the delta has changed over time, Vizza said, many aspects of the ecosystem are also affected.

“All these things are connected,” she said. “... And so that’s what I think is really fun and unique about this collaboration -- is that we have so many people with different specialities that focus on this one really important and very interesting area.”

Processes within the ponds

Fig.2: Carmella Vizza collects samples in the Copper River Delta ponds. (Credit: Andrew Morin)

Another characteristic of the delta is the various ponds that make it up. Ponds and other bodies of water are sprinkled throughout the watershed area and are host to various ecological processes.

Vizza herself focuses on microbial processes within the ponds and what chemical influences affect them - changes that are so important yet so small that the naked eye can’t see them. By studying these processes, Vizza is able to determine what organisms are the primary producers in the environment, fueling activity in the ponds. She also looks at decomposition, which she says is especially tied to climate change in the delta because of the depletion of oxygen. Oxygen depletion leads to methane production - one of the major contributors to greenhouse gases.

“Wetlands are the largest natural source of methane emissions to the atmosphere. So they provide about 60 percent of all natural sources,” Vizza said. “... That literally is all of the emissions from fossil fuels, cow farming and rice cultivation combined.”

And in order to get answers about the processes and influences within the delta’s ponds, Vizza and others must go into the field themselves and collect.

Collecting from the ground floor

Vizza and others working on the project collect the samples themselves. After a long morning of traveling to the delta, the team collects a variety of items from the field: water samples; tissue samples from plants, insects and other species; as well as sediment core samples.

While project participants often analyze samples themselves, they are at times sent to the Milwaukee Public Museumhttp://www.mpm.edu/ post analysis to serve as part of the archived collections. Through analyses, researchers are able to trace nutrients through the echelons of the food web or determine what hydrological processes are taking place from examining water chemistry. But, in the end, Vizza said they hope the data from the samples they collect serves as a baseline for future studies.

“We are looking at influences of climate change right now, but also we’re hoping that this data would serve as data for somebody to look at in maybe 50 years from now to see how much the Copper River Delta has changed,” she said.

And while Vizza said she believes they aren’t using collections in as novel ways as other research projects, they are on the ground and seeing the research all the way through.

“I think, in general, collections-based research is really the heart of science, so it’s a way to collect data and samples so we can analyze trends in a systematic way,” she said. “And so that gives us an idea of about what’s happening in these different ecosystems.”

(2009). Current research in the stream ecology laboratory. Retrieved from: http://www3.nd.edu/~strmeco/research.html.

Chaloner, D.T., K.M. Martin, M.S. Wipfli, P.H. Ostrom, and G.A. Lamberti. (2002). Marine carbon and nitrogen isotopes in southeastern Alaska stream food webs: evidence from artificial and natural streams. Can. J. Fish. Aquat. Sci. 59:1257-1265. Retrieved from: http://www3.nd.edu/~strmeco/gary/PDF%20Files/Chaloner2002.pdf

USFS, G. Reeves, M. Berg, G.A. Lamberti. Ecological Role of Elodea in Lakes and Ponds on the Copper River Delta, Alaska. Retrieved from: http://copperriver.org/files/elodea-meeting-presentations/gordie-reeves.

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