How Changes in Water Quality Today Impact Sustainability Tomorrow

A drive along the Albemarle-Pamlico Peninsula on North Carolina’s coast looks different today than just a few years ago. Dying trees—cypress, cedar and others—stand eerily draped in moss, the freshwater beneath them invaded by salty seawater.

These “ghost forests” are one of the most visible signs of the environmental changes happening in coastal regions as a result of saltwater intrusion. But the intrusion of saltwater into freshwater ecosystems can also impact farmlands, water sources, forestry plantations and other coastal resources.

Dr. Marcelo Ardón, an assistant professor in the Department of Forestry and Environmental Resources, aims to understand the human and natural processes influencing salinization of surface waters and adjacent lands. Ardón and a team of researchers are collaborating to map the extent and impact of the intrusion of saltwater into freshwater ecosystems.

Broadly focused on the structural and functional responses of wetlands and streams to local land-use and climate change, Ardón and his team want to understand whether current and emerging management tools can reverse the degradation, or restore the functioning, of wetlands and streams.

“We’re trying to connect the dots using long-term monitoring, lab and field experiments, remote sensing, and citizen science to understand the changes that are occurring now, in hopes of anticipating problems that are coming tomorrow,” Ardón says.

NSF Funded Projects in North and Central America

National Science Foundation (NSF) grants fund two of Ardón’s projects on the North Carolina coast and one in Costa Rica. In NC, the spotlight is on saltwater intrusion and ghost forests. In Central America, streams take center stage.

Teams in each location collect water and soil samples, analyzing them for carbon, nitrogen, phosphorous and other elements.

On the North Carolina shoreline, Ardón and his team are searching out explanations for increasing salinity in freshwater-based ecosystems and examining its impact on both ghost forests and farmlands. In Costa Rica, researchers study streams at the base of a dormant volcano, zeroing in on chemical changes in the water that seem to fluctuate depending on the amount of rain in the region.

Ultimately, they’re all trying to answer the same question: how are changes in water quality and quantity connected?

One of the biggest challenges they’ve faced is the reality that answers have not been as straightforward as expected. For example, when looking at saltwater intrusion, you might expect a simple formula to explain how much salinity specific ecosystems can endure without being damaged.

Ardón says it’s far more complicated. Salt itself is a complex mixture, so some parts of it—in low concentrations—are good for plants or microbes. Those same parts become dangerous in higher doses. Separating the different components to understand how each impacts plants and microbes presents a unique challenge.

Sometimes it’s frustrating, Ardón says, when the best answer to public-land managers’ questions is, “It depends.” But where the land and water are, what happens in both, whether it’s a flood or drought year—all impact the quality of water in sounds and streams.

“The changes that are taking place are complicated, and it’s hard to come up with simple answers or simple guidelines that people can directly use,” he says. Still, Ardón believes understanding what’s happening now will better inform the future.

In the long run, farmers in the Albemarle-Pamlico Peninsula, managers of public lands and directors of nature conservancies could all benefit from the results of Ardón’s work and the long-term goal of developing practical solutions to protect crops, wildlife refuges, land and water. Before getting to those solutions, though, understanding the extent of the problem is priority, and that’s where Ardón and his team are staying focused.

Collaborating with Ardón on the NSF’s Coastal Science, Engineering and Education for Sustainability (SEES) grant are NC State associate professor and hydrologist Ryan Emanuel; Duke University ecologists Emily Bernhardt and Justin Wright; and UNC-Chapel Hill associate professor Todd BenDor, a land use and environmental planning specialist.

Ardón’s project focused on ghost forests is funded through a NSF CAREER award. This project is centered on understanding the causes and consequences of the transformation of forested wetlands to ghost forests. Ardón and his team are trying to find signals that could help managers identify areas where forests are transitioning to ghost forests, in an effort prevent or accelerate that transition, depending on the managers’ goals.

“We know forests, wetlands, and natural ecosystems provide a natural infrastructure that can clean water a lot cheaper than we can. We’re asking how these systems are going to function in the future. Will we lose some of that capacity?”

The answer to that question holds a key to better management of land and water resources and a more sustainable tomorrow.