Underwater weeds increase in Chesapeake Bay in 2022

Underwater weeds increase in Chesapeake Bay in 2022

Underwater weeds increase in Chesapeake Bay in 2022

Annual aerial surveys showed continued recovery

Widgeon grass is now the most common submerged aquatic plant in the Chesapeake Bay. Maryland Department of Natural Resources photo

The Maryland Department of Natural Resources today reported a 6% increase in submerged aquatic plants, known as SAV or underwater weeds, in the Maryland portion of the Chesapeake Bay in 2022. Scientists mapped 37,297 acres of underwater weeds in Maryland during the annual survey . The results represent 47% of the state's 2025 restoration goal and 33% of the final restoration goal of 114,065 acres.

The Chesapeake Bay experienced moderate to dry conditions in 2022, which may have contributed to this increase. The area of ​​underwater grass in the Bay decreased significantly in 2019 and 2020 after heavy rains inundated the area in 2018. The resulting runoff brought more nutrient and sediment pollution into the Chesapeake Bay, blocking the water and preventing sunlight from reaching the grass bed beneath. water.

“As we celebrate continued positive signs of recovery in the Chesapeake Bay, we must remain vigilant to build resilience for this vital marine resource,” said Josh Kurtz, Maryland Secretary of Natural Resources. “To do this, we are evaluating habitat restoration methods to promote underwater grass growth. The Moore-Miller Administration is focused on ensuring these types of clean water benefits are distributed across Maryland’s watersheds to provide recreational and economic opportunities for all who depend on the bay.”

Underwater grasses play a critical role in the health of the Chesapeake Bay ecosystem by providing habitat and food for many species of fish, crabs, and waterfowl. They improve water quality by absorbing excess nutrients, reducing sediment erosion, and enhancing oxygen levels. Underwater weeds also reduce acidification associated with climate change, benefiting shellfish such as crabs, oysters, oysters and scallops.

Since the late 1990s, the Maryland Department of Natural Resources has been working with federal, state, and local partners to increase the area and diversity of underwater grasses in the Maryland portion of the Chesapeake Bay by Direct restoration– Planting plants or seeds of native SAV species in areas where they are not currently found.

In 2022, underwater grasses in all or part of five Maryland rivers exceeded restoration goals. These included the Northeast River at 111%; Bush River, 112%; the Upper Gunpowder River, 149%; the Wicomico River, 124%; and the fresh tidal portion of the Chester River by 507% (the percentage of target achieved is very high due to the target of restoring a very small portion). Two additional areas in Maryland have reached 75% or more of their restoration goals, including the Northern Chesapeake Bay and Mattaman Creek.

Among the notable areas that showed positive underwater weed growth were the popular beds of Tangier Sound and Susquehanna Flats, along with those in the lower Patuxent River, Bohemia River, Little Choptank River, and lower Pocomoke River. In a new development, scientists have observed underwater weeds in Cocoold Creek in the lower Patuxent area for the first time since the survey began in 1984.

More than 15 types of underwater herbs They are common throughout the Chesapeake Bay and are distributed primarily on the basis of their salt tolerance. More than a dozen species are found in the less saline and freshwater areas of the upper bay and its tributaries. In the brackish waters of the middle of the Gulf, only about four species of weeds are usually observed; In the saltier areas of the lower bay, only wedge grass and eel grass are found. Eelgrass in the lower bay is recovering and is important habitat for juvenile blue crabs; While wedgegrass has recently replaced eelgrass as the most abundant underwater weed in the Gulf.

Favorable conditions in 2022 played a critical role in the observed increases in weed abundance in areas of low to moderate salinity, known as mesohalene zones. However, the freshwater intertidal portions of the Gulf and areas with low salinity showed a slight decline in freshwater fish species.

Significant reductions in underwater weeds were observed on the upper western shore, especially in the Gunpowder and Middle Rivers and the adjacent upper beaches of the Chesapeake Bay.

The distribution of underwater weeds in the bay and its tributaries for 2022 was determined during an annual aerial survey conducted by the Environment Agency Virginia Institute of Marine ScienceUsing multispectral digital images and satellite images. Aerial images were acquired between May and October 2022 and include 180 flight paths. To supplement the gaps in aerial imagery and provide a complete dataset for the Chesapeake Bay, additional images were acquired from Maxar, Planet Labs, and Spot Image. Bay-wide results were reported by the Chesapeake Bay Program.

More information about underwater weeds in Maryland is available at the website Department of Natural Resources website.

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