2023 Maryland Underwater Grasses Survey

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Eelgrass Chesapeake Bay
Eelgrass | Credit: USGS

Abundance of submerged aquatic vegetation (SAV) remained steady in 2023 in the state’s portion of Chesapeake Bay, reaching 37,770 acres, according to recently released data by the Chesapeake Bay Program and Maryland’s Department of Natural Resources (DNR).

Surveys indicate a 7% increase over 2022 SAV acreage. Approximately 82,937 acres of SAV were distributed throughout Chesapeake Bay and its tidal tributaries in 2023, according to the study.

In Maryland, all or part of four rivers surpassed their restoration goals. These include the Northeast River at 109%, the Upper Chester River at 432%, the Honga River at 138%, and the Wicomico River at 270%.

An additional three segments reached 75 percent or more of their restoration goals, including the Northern Chesapeake Bay that encompasses the Susquehanna Flats at 86%, the Bush River at 83%, and Mattawoman Creek at 98% of their goals.

Submerged aquatic vegetation, also known as underwater grasses, absorb and filter out nutrients and sediment, reduce shoreline erosion, provide habitat and protection for important species such as blue crabs and largemouth bass, support and sustain migrating waterfowl, and mitigate climate impacts.

The annual underwater grass survey was conducted by the Virginia Institute of Marine Science between May and November 2023. While the acreage falls short of Maryland’s 2025 restoration goal of 79,800 acres, airspace restrictions prevented complete surveys of the Upper and Middle Potomac River, including Piscataway Creek. If these areas had been fully mapped, observations suggest that Maryland’s SAV acreage would have been higher in 2023.

A significant loss of freshwater grasses in the upper Bay in 2023 offset an equally significant expansion of brackish water grasses in the mid- and lower portions of Maryland’s Chesapeake Bay. The loss of freshwater grasses did not extend to the iconic Susquehanna Flats grass beds, which continued to expand and now cover over 11,000 acres.

In the mid-bay, the continued expansion of Sago pondweed (Stuckenia pectinata) contributed to SAV acreage. According to observations made by Bay scientists and data collected by Chesapeake SAV Watchers volunteers, Sago pondweed is possibly the most abundant species in several Maryland rivers on both the eastern and western shores, including the Severn and Choptank Rivers, and Eastern Bay.

Further south and into slightly saltier water, widgeon grass (Ruppia maritima) continued to recover from major losses in 2019. Both widgeon grass and eelgrass (Zostera marina) are common in Tangier Sound, where grass beds gained 1,285 acres of SAV between 2022 and 2023.

The overall health and expansion of SAV in the Chesapeake Bay are vital for the ecosystem’s resilience and the overall water quality. These underwater grasses are essential for providing habitat, food, and shelter for various aquatic species, thus supporting the biodiversity of the region.

source: Maryland Department of Natural Resources

 

Related Information

Chesapeake Bay Aquatic Vegetation

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