Close to 15,000 acres of underwater grasses have disappeared from the Chesapeake Bay.
While robust grass beds on the Susquehanna Flats and expanding beds in the James River offer two examples of the Bay’s resilience, an aerial survey conducted by the Virginia Institute of Marine Science (VIMS) showed a 21 percent decline in the Bay’s grasses in 2012. This so-called “alarming” loss—from just over 63,000 acres in 2011 to just over 48,000 in 2012—approaches lows last reported in 1986.
In a report released this week, Chesapeake Bay Program scientists attributed last year's decline in grass beds to warmer-than-normal water temperatures seen in 2010 and strong storms seen in the fall of 2011. The former "cooked" grasses in the Lower Bay, while the latter pushed excess sediment into rivers and streams, clouding the water and creating unfavorable growing conditions for aquatic plants in the Upper and Middle Bay.
These strong storms and episodes of heat stress have occurred alongside a widespread decline in water clarity, said Bob Orth, coordinator of the VIMS Submerged Aquatic Vegetation Survey. While Orth remains "concerned" over the decline in bay grasses, he noted that favorable growing conditions in the future could lead to quick signs of recovery in a species that is fast to respond to water quality changes—both good and bad.
"The best thing we can do [for bay grasses] is to improve water quality," said Lee Karrh, a biologist with the Maryland Department of Natural Resources (DNR) and chair of the Bay Program's Submerged Aquatic Vegetation Workgroup. "If you improve water quality and reduce chronic problems, then the Bay should be able to deal with episodic events easier than it has been able to in the past."
Underwater grasses—also known as submerged aquatic vegetation or SAV—are critical to the Bay ecosystem, offering food and habitat to countless critters while absorbing nutrients, trapping sediment and reducing shoreline erosion. The Bay Program uses underwater grass abundance as an indicator of Bay health, and has this week released a data visualization tool that allows users to track changes in grass abundance over time, as dominant species ebb and flow and grass beds shrink and expand.
Read more about the 2012 Distribution of Submerged Aquatic Vegetation in the Chesapeake Bay.
Maryland Public Television (MPT) will celebrate the nation’s largest estuary with a week of Chesapeake Bay-related programming, to begin on Sunday, April 21.
Image courtesy Maryland Sea Grant
During Chesapeake Bay Week, a dozen programs will explore some of the most pressing issues facing the watershed, from the future of the agriculture and seafood industries to the health of iconic critters and waterways. An hour-long special called “Who Killed Crassostrea virginica?” will take a look at the demise of the Bay’s native oyster, while a 30-minute program called “The Last Boat Out” will follow a family of Virginia watermen as they question staying in the business of seafood harvesting.
Bay history, too, will be part of the annual event: “Black Captains of the Chesapeake” will highlight African Americans who have captained on the Bay, while “Growing Up on Tilghman” will explore what it was like to grow up in this quiet watermen’s community on Maryland’s Eastern Shore.
“There is really rich content within these shows,” said Betsy Peisach, MPT’s managing director for education marketing and outreach. Peisach encourages teachers, in particular, to bring these programs into their classrooms where possible. And for those who teach middle-school science, MPT has developed an online interactive that allows students to explore the Bay, whether it is through a virtual tour of the Bay’s varied ecosystems or an online cinema that features clips from Outdoors Maryland.
MPT will wrap up Chesapeake Bay Week with a concert and volunteer-a-thon to connect viewers with volunteer opportunities across the watershed.
The Chesapeake Bay Program is a sponsor of Chesapeake Bay Week this year. Learn more.
According to the results of a survey conducted by the Maryland Department of Natural Resources (DNR), oyster abundance has increased in state waters for the second consecutive year and more of the bivalves are withstanding pressures from pollution and disease.
The 2012 Fall Oyster Survey, which has monitored the status of the state’s oyster population since 1939, found a 93 percent oyster survival rate—the highest since 1985—and a lower-than-average prevalence of MSX and dermo, two diseases that have decimated the Chesapeake Bay’s native oysters in recent decades.
In a news release, DNR Fisheries Service Director Tom O’Connell attributed these successes to the establishment of oyster sanctuaries, which are closed to harvest and which could allow oysters to build up a natural disease resistance.
Maryland is currently restoring oyster reefs in the Harris Creek and Little Choptank River sanctuaries, as part of a federally mandated effort to restore oyster populations in 20 Bay tributaries by 2025.
Read more about the 2012 Fall Oyster Survey results.
More than half of the nation’s river and stream miles are in poor health, according to a new study from the U.S. Environmental Protection Agency (EPA).
The latest National Rivers and Streams Assessment, a sampling effort conducted during the summers of 2008 and 2009, found that 55 percent of the nation’s rivers and streams are in poor condition and 23 percent are in fair condition, their health impaired by nutrient pollution, a loss of streamside vegetation and bacterial and chemical contaminants.
These same stressors have impacted the Chesapeake Bay and its tidal waters. Excess nutrients can fuel the growth of algae blooms that suck oxygen from the water, creating “dead zones” within which animals cannot survive. A loss of streamside vegetation can boost erosion and push sand, soil and sediment into waterways, blocking sunlight from reaching underwater grasses and smothering the habitat that some aquatic organisms need to live or breed. And chemical contaminants—like, for instance, mercury—can accumulate in the tissues of fish, leading to fish consumption advisories in polluted waterways.
But rivers and streams are critical to the health of humans and wildlife alike, as sources of drinking water, food and habitat. According to the EPA, this survey suggests the need to better address pollution at its source, whether it is urban, suburban or agricultural runoff or the treatment of wastewater.