Bay Grasses Expected to Decline Due to 2018 Rainfall

Bay Journal article (2019-08-21) reported that sections of the Chesapeake Bay’s aquatic grasses are expected to decrease this year in response to heavy rains that caused increased nutrient and sediment runoff in 2018. The article noted that initial reviews of the 2019 aerial Bay grass survey show “significant losses” of widgeon grasses in the Mid Bay region, which has the most underwater grass beds in the Bay. Eelgrass beds in the Lower Bay also appear to be hit hard and these beds may not be able to recover due to climate change pressures, raising the concern of scientists.

Aquatic grasses are an important part of the Bay’s ecosystem, increasing the oxygen levels in Bay, reducing shoreline erosion, trapping sediment, and providing habit and food for birds, fish, and crabs. Restoring  aquatic grass coverage is key component in Bay restoration efforts.

The article noted that the news on aquatic grasses is not all bad, with initial survey reviews also showing greater resilience for more freshwater grasses in the Upper Bay, with some grass beds even expanding despite last year’s weather challenges. A full analysis of this year’s aerial survey of Bay grasses will not be available until early next year.

The article noted that the Bay restoration goal for aquatic grasses is 185,000 acres. In 2017, grasses hit a record 104,843 acres – the highest since Bay restoration efforts began. The 2018 aerial survey could only be partially completed due to the heavy rains and runoff but scientists guessed a completed survey would have shown around 108,000 acres.

From the article:

“It’s going to be a mixed story, as it always is,” said Bob Orth, the Virginia Institute of Marine Science researcher who has been overseeing the aerial survey since its inception in 1984. …

“I think we would have been well on our way to surpassing the 2017 levels if the last year hadn’t turned into such a muddy mess,” said Brooke Landry, a biologist with the Maryland Department of Natural Resources and chair of the state-federal Bay Program’s Submerged Aquatic Vegetation Workgroup. …

“Baywide, the story [was] really the huge expansion we’ve had in widgeon grass,” said Dave Wilcox, a VIMS scientist who works on the survey. “That’s what is driving our numbers in the last several years.” …

“[Eelgrass loss is] a concern, and part of the climate change scenario,” [Orth] said. That could leave large areas of the Lower Bay, where beds are especially important for juvenile crabs, denuded of vegetation.



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