Survey Indicates Slight Decline in Underwater Grass Abundance

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Despite record-rainfall in 2018, underwater grass abundance remains strong

Despite record-rainfall in 2018, underwater grass abundance remains strong

An annual survey led by researchers at the Virginia Institute of Marine Science mapped an estimated 91,559 acres of underwater grasses in the Chesapeake Bay and its tidal tributaries in 2018.

While this acreage is less than the previous year, it is likely that substantially more submerged aquatic vegetation (SAV) grew in the Bay than the mapped acreage suggests: frequent rain, cloudy water, and security restrictions prevented researchers from successfully collecting aerial imagery over 22% of the monitored area, including the Potomac River near the Patuxent Air Base; portions of the Susquehanna Flats; Mattaponi, Middle, Choptank, and Honga rivers; and Fishing Bay.

In 2017, these unmapped portions of the Bay supported more than 17,401 acres of grasses. Adding this value to the 2018 estimate would bring the estimated total for 2018 to 108,960 acres—a 4% increase from 2017 levels and a 59% achievement of the Chesapeake Bay Program’s 185,000-acre 2025 goal. The 2017 total was the greatest amount of underwater grasses ever recorded by VIMS’ SAV Monitoring and Restoration Program, and the first time total grass abundance surpassed 100,000 acres. VIMS scientists began monitoring the Bay in 1979.

Read More at Virginia Institute of Marine Science