Underwater Grasses

By providing food and habitat for wildlife, reducing shoreline erosion and improving water quality, underwater grasses serve as an important piece of the Bay ecosystem.

Underwater Grasses

In 2016, about 97,433 acres of underwater grasses were mapped in the Chesapeake Bay. For the second year in a row, this total marks the highest amount ever recorded by researchers at the Virginia Institute of Marine Science. Moreover, it is likely that more submerged aquatic vegetation grew in the region than this estimate suggests: weather conditions and security restrictions prevented researchers from acquiring data for a portion of the Potomac River, and trends suggest this area would have put the Bay-wide total at 99,409 acres, had it been mapped.


Acres of underwater grasses in the Chesapeake Bay

Researchers attribute the rise in underwater grass abundance to a strong increase in the tidal freshwater and moderately salty regions of the Bay. The iconic grass beds at the mouth of the Susquehanna River, for instance, continued their four-year recovery following damage from Hurricane Irene and Tropical Storm Lee. And at over 10,000 acres, the grasses that stretch from Smith Island to Tangier Island have become the biggest contiguous grass bed in the Bay. Widgeon grass, in particular, expanded in this bed and other moderately salty waters, but because it is a “boom and bust” species whose abundance can rise and fall from year to year, a widgeon-dominant spike is not guaranteed to persist in future seasons.

While this total is just under half of the acreage the nation's largest estuary once supported—and 53 percent of the 185,000-acre goal to which the Chesapeake Bay Program has committed—it is 7,433 acres greater than the partnership's 2017 restoration target.

A continued rise in bay grasses will benefit the entire Bay ecosystem: underwater grasses absorb nutrient pollution, improve water clarity, reduce shoreline erosion, and provide food and shelter to striped bass, blue crabs and other critters.