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Chesapeake’s grasses hard hit by heat, high flows in 2019

July 8, 2020

Bay Journal — By Karl Blankenship — July 8, 2020

"Overwhelmed by record high flows and warm temperatures, the Chesapeake Bay’s vast underwater meadows last year suffered their largest drop since surveys began, with acreage plummeting at least 33% from 2018.

But the declines were not uniform throughout the Bay. Underwater grass beds in many fresh and low-salinity areas of the Chesapeake and its tidal tributaries held their own, while beds in mid– and high-salinity areas suffered the brunt of the impact.

“We see a lot of little losses in a lot of places, and little gains in a lot of places,” said Christopher Patrick, assistant professor of biology at the Virginia Institute of Marine Science, which conducts the annual aerial survey of the Bay’s grass beds. “And then we’ve had a couple places that just had a really bad year.”

The Bay lost a bit more than 34,986 acres of submerged aquatic vegetation, or SAV, erasing nearly a third of the plants from the shallow waters around the Bay.

The loss was probably larger, scientists say, but it wasn’t fully documented: Bad weather kept them from completing the survey in 2018.

The 66,387 acres of Bay grasses mapped last year represented just 35.9% of the Bay Program restoration goal of 185,000 acres.

“The significant loss of Bay grasses this year is a sobering reminder that the Chesapeake Bay is still a system dangerously out of balance,” said Beth McGee, a scientist with the Chesapeake Bay Foundation. “The extreme flows of polluted runoff that damaged the grasses are also a clear sign that climate change is threatening the Bay’s recovery. This setback should be a wakeup call that climate change and increasing pollution cannot be ignored.”

Grasses are considered one of the most important indicators of Bay health because they require clear water to survive. Chesapeake nutrient reduction goals are aimed at improving water clarity enough to reach the underwater grass restoration acreage target.

Still, scientists feared the loss could have been even greater. According to the U.S. Geological Survey, 2019 had the highest volume of river flows since the monitoring of river flows into the Bay began in 1937. . ."

Read the full article at the Bay Journal


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