OCEAN CITY — In the northern coastal bays of Worcester County, hot weather and poor water quality contribute to killing 95 percent of bay grasses.
The data comes from a May 7 survey showing an overall decrease of underwater sea grass by 35 percent. The changes came from July 2010 to May 2011, and include no official data from 2010. “We have lost nearly 20 years of sea grass recovery and the primary nursery for crabs and fish along with it,” said Dave Wilson, executive director of the Maryland Coastal Bays Program. His group worked jointly on the annual survey with the National Park Service and the Maryland Department of Natural Resources. The survey shows there were 13,863 acres of underwater grasses in summer 2010. The next spring, measured grasses came to 9,083 acres — that’s 4,780 acres gone in less than a year. Areas of Assawoman Bay and Isle of Wight Bay were “completely wiped out,” Wilson said. “That’s not a good thing, especially considering the value of those grasses.” Chincoteague Bay took the greatest hit, losing more than 2,500 acres, or 27 percent. The northern coastal bays lost 95 percent of their acreage, comprising about 1,500 acres of grass. “You lose 95 percent, it would be like saying we’re going to cut down 95 percent of the woods … and expect all the woodland-dwelling creatures to survive; it just doesn’t work,” Wilson said. Bay grasses are important because they’re a barometer of water quality. And there’s a significant amount of marine life in the coastal bays, with a mix of southern and northern species here in the mid-Atlantic, Wilson said. Some of the surviving species will do their best to survive on algae. Juvenile flounder might survive, but it’s not likely. Sea horses and pipe fish and others need sea grasses to live. Wilson said preliminary surveys this spring show some shoots of grass coming up, “but boy, it’s nothing like it was. It’s not like a thick, lush forest or anything. … It doesn’t come back all in one year.” It leaves the coastal bays with even less sea grass than was lost during another particularly hot summer, in 2005. Wilson said it was a gradual buildup to where they were; recovery is a slow process. Wilson couldn’t pinpoint any particular cause for such a grand die-off of sea grasses. Heat is the big factor, though, and the environment is its own worst enemy. When a big chunk of bay grasses die in a heat spell, they go from living organisms to pieces of floating, decaying nutrients. That, in turn, contributes to a more toxic environment, and even more grasses will die. Wilson said his biggest concern from an ecological standpoint is the trending warmer weather. And while water quality has pretty much held its own in the northern coastal bays, it’s declined in the southern coastal bays. “The combination of warm weather and relatively high nutrient levels — which also causes a lot of turbidity, or lack of water clarity — is sort of a one-two punch for these grasses,” he said. Brian Sturgis, an aquatic ecologist for Assateague Island National Seashore, is one of the people who are on the ground to see how much of the bay grasses, or submerged aquatic vegetation, have survived. He visits 100 fixed sites every year to check for grasses. “The survey’s accurate,” Sturgis said. “We went up and ground truthed in the northern bays, where there wasn’t any showing up on the aerial photographs. We stuck our heads in the water and couldn’t find anything.” The impact to waterways is that habitat will be lost for lots of small fish and crabs. “There’s less area for those guys to grow up in. … With the grass areas, they can hide in there,” he said. “Plus there’s a bunch of other critters who do well in grass beds and really can’t survive outside of those.” The next annual aerial survey will happen sometime between May and August, depending on weather and water clarity, Wilson said.