You know that flowing underwater grass known to catch occasionally on a keel or rudder, or foul a prop? Well it’s called submerged aquatic vegetation, and it’s important to the Bay’s ecosystem. It was dangerously on the decline in the 1960s and 70s, but it seems to be making a comeback thanks to environmental efforts begun in the 1980s. That’s good news, because underwater grasses are a key indicator of water quality.
[caption id="attachment_96116" align="aligncenter" width="771"] Photo courtesy of the MD DNR[/caption]
Recently the Maryland Department of Natural Resources reported that underwater grass abundance in Maryland’s portion of the Chesapeake Bay increased 29 percent between 2014 and 2015 (the most recent data), reaching a new record of 53,277 acres. This puts Maryland at nearly 94 percent of its 2017 restoration goal of 57,000 acres.
“The record resilience and resurgence of underwater grasses indicate that Maryland is making progress on Chesapeake Bay restoration and improving water quality in the watershed,” says Natural Resources secretary Mark Belton.
Underwater grasses are essential to a healthy ecosystem for many reasons. They absorb and filter out nutrients and sediment and reduce shoreline erosion. “Grasses cement together sediment grades and hold them in place,” says Doug Myers of the Chesapeake Bay Foundation (CBF). When grasses are plentiful, sediment and nutrients are less likely to become suspended in the water due to wind and waves. They also buffer further movement of sediment that’s already suspended. I saw this firsthand last weekend on the Potomac. It was a windy day, and the main stream was muddy and brown. However, in the grass beds near the shoreline, the water was significantly clearer, and it became very clear when the wind died, while the main stream remained cloudy.”
Submerged grasses are home to spawning fish, crustaceans such as the blue crab, and other delicate marine life such as the lined seahorse, which can be found in the grassy shallow waters of the Lower and Middle Bay. Underwater grasses are important to birds, too. Waterfowl feed on them, and migratory birds eat their seeds and tubers.
The Virginia Institute of Marine Science (VIMS) has a seagrass monitoring and restoration program that tracks the abundance of underwater grasses by field and aerial observation. They report that the latest values are the highest they’ve ever recorded. While the most recent report doesn’t include data from 2016, initial aerial views look promising. “We have some fairly good indications that this year will be as good as last based on anecdotal reports and the clarity of the water this late in the year,” says Myers. He adds, “Improved water clarity isn’t a fluke. It’s bearing out that nutrient reduction under the Clean Water Act is working.”
You can help grow grasses in Virginia’s rivers by participating in the CBF’s Grasses for the Masses program. Participants grow wild celery grass in a simple grow-out system in their homes for 10 to 12 weeks; then they gather to plant their grasses in select local rivers.