It’s not easy to get to Hog Island, a narrow, roughly 7-mile-long stretch of land off the Eastern Shore that straddles a seaside bay and the Atlantic Ocean.
You need permission to access much of the nature preserve, and a boat to navigate there.
Then there’s another complicating factor: the shape of the island is constantly changing.
“It's like a drumstick that rotates where, historically, in the last century, the northern island was the meaty part,” said Julie Zinnert, an associate biology professor at Virginia Commonwealth University. “Now the northern end is eroding and becoming narrower and the southern end is growing out and becoming that meaty part.”
The dynamic nature of the island can sometimes make it difficult to study, but that’s exactly why Zinnert wants to do so.
Her research team is exploring how Hog and other nearby islands respond to changing environmental conditions – and the best strategies humans can use to protect them.
Barrier islands shield the mainland Eastern Shore from the worst effects of storms by bearing the brunt of the most intense waves and winds.
Now, the land is at risk from rising sea levels and other impacts of climate change.
No one lives on Virginia’s barrier islands anymore. Zinnert said that makes them the perfect place to study what happens in a natural setting.
“We have a unique opportunity in Virginia to examine how the islands change over time,” she said.
Shifting sands
Hog Island was once home to the only established town along the Commonwealth’s barrier islands, called Broadwater. The last of its residents were driven off by a series of hurricanes in the 1930s.
It’s now one of 14 barrier islands part of the Nature Conservancy’s Volgenau Virginia Coast Reserve. The Conservancy, a nonprofit, says the islands shelter more than 250 species of raptors, songbirds and shorebirds.
The narrow strips of land also help buffer some of the ferocity of hurricanes and nor’easters before they reach shore and cause erosion and flooding.
“By having these, they can prevent storm damage from being quite as extreme,” Zinnert said.
Barrier islands are made of sand, subjecting them to the whims of winds, waves and tides. They naturally morph over time.
The biggest threats to the islands are climate change and human development, which accelerate those changes.
Building along barrier island shorelines – such as on the Outer Banks — contributes to erosion by preventing sand from moving freely.
“Without natural island migration, dunes frequently erode and need to be rebuilt every few years,” Zinnert’s team wrote in a recent scientific paper designed for young readers. “This process is incredibly expensive and affects animal communities along the sea floor by disturbing and destroying their habitats."
Sea level rise driven by climate change increases the amount of water that washes onto the islands and causes them to move faster. Rising temperatures also impact where and how well plants grow, which in turn affects the formation of sand dunes.
Researchers at William & Mary’s Virginia Institute of Marine Science recently found that losing land on Virginia’s barrier islands rapidly releases carbon dioxide that was naturally stored in lagoons and peat deposits.
They said the Virginia chain has now “flipped from a carbon sink to a carbon source,” releasing more carbon each year than it captures.
The importance of dunes
Zinnert has been researching Virginia’s barrier islands for over a decade. She said each time she visits – even if it’s just weeks or months apart – she sees changes in the landscape.
Her team at VCU is especially interested in sand dunes and the grasses that grow on them, which help create the mounds by trapping in sediment.
The group planted plots of dune grass on Hog Island in the spring. Last week, with the growing season coming to a close, it was time to check on the plots and collect samples to take back to Richmond.
Anne Sciolino, a graduate student focused on coastal plant ecology, said they planted different species of grasses and in different combinations.
The goal is to assess the best strategies for successful growth patterns.
It sounds technical, but Sciolino said dune grasses are important to inland human structures and infrastructure that use them as a protective barrier.
“What people do a lot of times is they’ll plant these grasses to help rebuild the sand dunes,” she said.
“But a lot of times the plantings are not very successful. A lot of times they die. So the goal of this project is to find the best planting design to help the plants survive better, which saves money.”
Elsewhere on the island, Alex Sabo and Ryan Hearl measured land elevation, focusing on spots with high density of dune grass.
By collecting the detailed data on site, Sabo said the researchers can then plug it into computer modeling and see how the dunes develop alongside combinations of plants.
“Virginia Beach, Norfolk, they all have huge dune systems, and we've pretty much built houses right up along the beach in all of these locations,” said Sabo, a recent VCU master’s graduate who now works at VIMS.
“If we can get a better understanding of how these dune grasses grow and shape and interact with one another, we can help better prepare for future changes in the climate system and work in this natural system where we have put lots of human structures.”
Earlier this year, Sabo and Zinnert helped author an article published in the journal Scientific Reports based on Virginia’s barrier islands.
It found that when dunes are lower to the ground, more seawater can flow to the center of the island, altering soil chemistry and how much sediment ultimately accumulates.
They emphasized that it’s important to incorporate research on these dune systems into future predictions of sea level rise.
Zinnert said the goal is to apply what they learn to areas where barrier islands are developed and inhabited, like the Outer Banks.
“How much can you invest in the system to maintain it?” she said. “Versus it turning into Rodanthe, where it's no longer feasible to try to maintain that because it's too costly.”
