It was a bad sign last spring when Bob Orth answered the phone and the words spilled out from the other end. “Where did all the grass go?” The fisherman on the line had for years been catching speckled trout in the large bed of eelgrass at Dameron Marsh near the mouth of the Potomac River.
Now, the caller said, it was gone.
Orth, a seagrass researcher at the Virginia Institute of Marine Science, and several colleagues shortly thereafter visited the marsh, a site where they had previously found lush beds of the underwater grass. Now, they found mud.
“I was shocked,” Orth said. “We didn’t find hardly any eelgrass at alI. It was a disaster.”
Dameron Marsh isn’t alone. VIMS scientists estimate that two-fifths or more of all eelgrass beds in the Lower Chesapeake Bay vanished the last two years. Lost with them are swaths of crucial habitat for blue crabs, speckled trout, waterfowl and a host of other species. “This is the sad state of affairs for eelgrass in most of the Bay now,” Orth said.
It is an acceleration of a slow-moving ecological crisis that has taken place over the last quarter century, triggered by persistent poor water quality and, increasingly, by climate change as eelgrass does not tolerate the Bay’s warming waters.
Beds of eelgrass once formed vast meadows in high-salinity parts of the Bay. It was so abundant in the early 1900s that people used it to insulate their homes and fertilize fields. As recently as the 1960s, its range reached north almost to the Bay Bridge. Today, it barely stretches into Maryland.
As a warming climate continues to bake eelgrass beds, scientists say it’s less a question of whether eelgrass will mostly vanish from the Bay, but how long it will take.
For the Lower Chesapeake, the implications are huge. The Bay is home to about two dozen species of underwater grasses, but most live in fresh or brackish water. Eelgrass has historically been the dominant species in high-salinity water of the Lower Bay. The only other species that will tolerate high-salinity water can occupy only some of the areas where eelgrass meadows once existed, and it does not perform all of the same functions.
As eelgrass declines, more areas of the Lower Bay will increasingly look like Dameron Marsh.
“In a world that is getting warmer and wetter, it’s kind of hard to summon up a lot of optimism for eelgrass,” said Jonathan Lefcheck, a research scientist with the Smithsonian Environmental Research Center in Maryland. “If I were a betting man, I’m not sure I would bet heavily on the future of eelgrass here.”