Matt Whitbeck stands at the end of this wooden walkway that stretches over an expanse of green marsh grasses, putting tourists right in the middle of a vibrant wetland. Around the deck, one can spy red-winged blackbirds, buzzing insects and the occasional jumping fish.One major cause of the expansion of open water in the Blackwater refuge was the invasive rodent Nutria, which have recently all but been eliminated there. This may well alleviate the problem, as it was intended to do. And if people would stop burning the marsh, that would help, too.
Whitbeck is a wildlife biologist at the Blackwater refuge, which occupies around 28,000 acres of forests, marshes and water in Dorchester County on Maryland’s Eastern Shore. Today, he’s interested in the transitions that are occurring across this landscape. Over the decades, Lake Blackwater — which occupies around 4,000 acres at the center portion of the refuge — has grown bigger and bigger, Whitbeck said. And acres and acres that were once marshland have been covered in water, killing off the plants there.
But new marshes are forming here, too. Whitbeck points to a line of sickly looking loblolly pine trees in the distance. Because of the encroaching water, the area is now too salty for them, he explained. When those trees die, though, marsh plants will grow in around them.Sure, as waters rise, new ground is affected and wetland shift inland. It's been that way since the last set of continental glaciers began to retreat at the end of the last glaciation about 20,000 years ago. At that time, the land went out to the shelf break on the Atlantic shore, and the Chesapeake Bay as we know it did not exist, only the Susquehanna River at the bottom of a river valley that had once been a Bay (or more like 3 times) and would be again.
“You can see, essentially, the habitat transition in action. I mean, you can see that line of dying trees. You can see the marsh encroaching,” Whitbeck said. “It’s happening in front of our eyes.”
The driving force behind these transitions is sea level rise — brought on by man-made climate change and the sinking of land surfaces around the Eastern Shore. Rising waters have claimed more than 5,000 acres of marshland in the refuge since it was established in the 1930s. That’s close to half of Blackwater’s historic wetlands.While it's true that the land on the eastern shore is sinking, both naturally as a result of post glacial readjustments in the earth's crust, and as a result of water withdrawals, it is not true the "man made climate change" is causing it:
One way is to help marshes do what they have done for a long time. Sea level in the region has gradually risen for thousands of years, and geologic evidence collected from around the Bay shows that marshes have responded in two ways. They have either grown upward by collecting enough sediment and decomposed plant matter to keep pace with the rising water or have moved away from the water, farther inland.Actually, most of the marsh is lost to erosion at the edges. The salt marshes have no trouble growing up to match sea level rise at it's current rate.
Moving inland will likely be crucial if marshes are going to survive rising sea level. As the water rises, the lowest-lying marshes, or those closest to the Bay, will become submerged and die.
Meanwhile, the Bay will move inland to dryer and higher land. This influx of salty water will kill off forests like the lines of loblolly pines near Lake Blackwater. Marshes, in turn, will replace those forests.In fact, there's pretty good Striped Bass and Speckled Trout fishing out in submerged fields of stumps off the Eastern Shore Islands. When you go looking, you'll see a lot geological history out there.
“The whole process has been going on for a long, long time,” Whitbeck said. “The marshes we have here are currently riddled with old tree stumps.”
The problem will come when the marshes moving back run into human habitation. Unlike marshes, road, houses and parking lots don't rise with sea level without human effort. And these days, the US government has been on a mission not to allow those kinds of effort.