By VASG Science Writing Intern Erika Lower
The Chesapeake Bay Bridge-Tunnel looks like it goes on forever in the early morning light. Stephanie Chavez, my fellow Virginia Sea Grant intern, consults the GPS from the passenger seat and assures me that we’re still making good time on our drive up the coast. It’s been drizzling on and off for the last hour, but that won’t matter – where we’re headed, we’ll be getting wet anyway.
We’re on our way to a boat launch in Oyster, a small town on Virginia’s Eastern Shore, to meet with Dr. Richard Zimmerman and Dr. Victoria Hill, Virginia Sea Grant funded seagrass researchers from Old Dominion University. We visited them last week at the Virginia Aquarium, where they showed us an experimental setup designed to measure the effects of temperature, pH, and carbon dioxide on eelgrass, a marine plant native to the Chesapeake Bay.
Eelgrass is a ribbon-like plant that provides habitat and shelter for a wealth of marine species, including scallops, crustaceans, and economically important fish. The Chesapeake Bay’s seagrass beds were devastated by a wasting disease in the 1930s, a blight which led to the near-collapse of a number of fisheries in the Bay. A remarkable restoration effort has been underway since 1999, when Virginia Institute of Marine Science (VIMS) Professor “JJ” Orth began to sow the then-barren bays with eelgrass seeds. Virginia’s coastal bays are now home to nearly 5,000 acres of eelgrass, making them the most successful example of seagrass restoration in the world.
The eelgrass recovery has been impressive so far, but how the plants will be affected by rising temperatures and CO2 levels is currently unknown. The experimental tanks at the Virginia Aquarium are designed to test these factors, but before they can be put to use, it’s necessary to harvest the plants that will fill them. Today Dr. Hill and Dr. Zimmerman have invited us out to get a first-hand look at the source of their research.
Dr. Zimmerman and Dr. Hill present us with safety equipment before we embark on the half-hour cruise to South Bay. Once we reach the harvest area, Dr. Hill anchors the boat and the researchers don diving gear. Although the water is only about five feet deep here, scuba equipment will help them stay submerged long enough to gather the plants efficiently. Armed with mesh collection bags and hand trowels, they lower themselves into the water and soon are only visible by the trail of bubbles they leave on the surface.
Stephanie is content to stay on the boat, but I’m curious about seeing the grass itself. The water carries enough suspended sediment that it’s impossible to spot the grass beds from the surface, so I grab the waterproof camera, hop overboard, and swim down to get a closer look.
In spite of the cloudy water that limits visibility beyond a foot or two, the success of the restoration efforts is readily apparent. A thick bed of eelgrass stretches out in all directions below the surface like a sunken prairie. Although the details are hard to make out, the filtered sunlight shines off the plants and fills the water with a bright green glow.
Dr. Hill and Dr. Zimmerman return to the boat, their nets filled with specimens. Stephanie and I help them load the eelgrass into water-filled coolers for transportation back to the aquarium. Today’s harvest didn’t take long. “We only need about 200 shoots right now,” says Dr. Zimmerman. “We can always come back and harvest more, but we try not to waste the species we’re trying to restore.”
We’ll need to hurry back – although the morning overcast has dissipated, billowing clouds on the horizon promise afternoon thunderstorms. On the way back to Oyster, the boat passes through long parallel rows of grass blades floating near the surface. Dr. Zimmerman explains that the lines are called Langmuir streaks, and they’re an encouraging thing to see — while the pattern itself is caused by the wind, the grass that creates it is a sure sign of the steadily rebounding ecosystem below the waves.