By the end of this decade, the Bay Program hopes to see more than twice as many acres of lush, underwater grass beds covering the Chesapeake’s bottom than what exists today. The state-federal partnership has adopted a new 185,000-acre restoration goal for the underwater meadows, which provide essential habitat for juvenile fish, blue crabs, waterfowl and other Chesapeake creatures.
That’s more than double the 85,000 acres estimated to have been in the Bay during 2001, the highest number since annual surveys began in the mid-1980s. And it’s more than anyone has seen in the Chesapeake for decades as the Bay’s increasingly murky waters have blotted the sunlight from above.
“This is a very aggressive goal,” said Mike Naylor, a biologist with the Maryland Department of Natural Resources who headed the Bay Program task force that developed the new target. “But if we restore light, we are quite confident the goal is achievable.”
To restore that light, the Bay Program in March adopted new cleanup goals that require a 48 percent reduction in nitrogen and a 53 percent reduction in phosphorus, measured from the mid-1980s, when Bay conditions were considered to be at their worst. Those nutrient reductions are aimed at reducing water-clouding algae blooms and improving oxygen levels in the Bay.
In April, the Bay Program established its first-ever sediment reduction goals aimed at clearing the water in areas where nutrient reductions alone won’t do the job.
Scientists and Bay officials believe the return of extensive beds of submerged aquatic vegetation—or SAV for short—will be a springboard to a healthy Bay filled with fish, crabs and waterfowl. Studies show that juvenile blue crabs may be up to 30 times more abundant in grass beds than in nearby barren areas. The decline of many waterfowl in the Chesapeake has been linked to the loss of grass beds, which were an important source of food. And many types of fish use grass beds as refuges during parts of their life cycles.
Once, hundreds of thousands of acres of grass beds filled the Chesapeake, but by 1984, they covered only about 38,000 acres.
The new grass goal was developed after Naylor and researchers from the Virginia Institute of Marine Science scoured photo archives for any aerial photographs showing Bay shoreline—mostly old agricultural surveys. While scientists had used such photos to document declines in specific places in the past, it was the first effort to document changes Baywide.
They examined hundreds of photos taken since the early 1930s and mapped the location of any grass beds they could see. Then, they looked for the most grass that could be documented in any single year within each of nearly 80 distinct segments along the shores of the Bay and its tidal tributaries.
That photographic evidence is the basis for new water quality standards to be adopted by the Bay states. The standards will require that the water be clear enough in each segment to allow at least as much grass to thrive as was observed during its best year.
“This new goal tells us that each of those segments actually contained these amounts of SAV in one year,” Naylor said. “Not in John Smith’s time, and not in some combination of years. So we really have something we can hang our hat on.”
Still, Naylor said the 185,000-acre figure is a conservative estimate of past underwater grass abundance. Because the photographs were taken for other purposes, grass beds are not always visible, and sometimes the photography was done during seasons when grass wouldn’t be present.
“There was certainly more SAV than that in the Bay,” Naylor said. “Open water areas weren’t photographed at all because these were land surveys. We have some photographs where the SAV continues beyond the edge of the photo.”
Also, the new water clarity standards only apply to depths down to 2 meters. No grasses seen at greater depths were counted toward the goal. And, areas more than a half-meter deep within a segment had to be covered with certain amounts of grasses to be counted toward the goal.
As a result, several thousand acres of grasses that were present were not included in the goal.
“There were some significant areas of SAV that were not captured by the goal that had been documented in either historic or annual SAV surveys,” said Bill Street, of the Chesapeake Bay Foundation. “So that is a good goal for 2010, but in the long run we certainly would like to go beyond that.”
It replaces the old goal of restoring 114,000 acres of grass beds in the Bay by 2005. That goal was based on returning grass beds to all areas where they had been documented since 1972.
“It certainly ratchets the goal up quite a bit,” said Bob Orth, a VIMS scientist who has coordinated an annual Baywide aerial survey of grass beds for nearly 20 years. “But I think there is a large amount of area in the Bay where grasses can become quickly established if the conditions are right.”
For example, Orth noted, recent years of drought—which resulted in less nutrient and sediment runoff because of reduced rainfall—demonstrate that grass beds can respond rapidly when water quality improves. The 2001 survey indicated that grass beds expanded 27 percent over 2000 levels, to about 85,000 acres—the highest level seen since the aerial survey began 1984.
An analysis of last year’s survey is not complete, although Orth said all areas examined so far showed increases over 2001.
But, he said, the test will be whether states and communities can curb runoff and manage growth to reduce nutrient and sediment pollution in years where there is no drought. “How are we going to do this when communities want to grow, and no one is saying, ‘Hey, wait a minute, this could be a problem?’”
Even water quality improvements alone don’t guarantee that the new goal will be met. Some areas with good water quality, such as parts of the lower Potomac, remain largely void of grasses, possibly because there are no grasses to begin with.
To jump-start grass beds in such areas, the Bay Program is writing a new SAV restoration strategy calling for the planting of 1,000 acres of new grass beds by the end of 2008, something that could cost millions of dollars.
“I do think the goal is attainable, but it is going to take a huge political commitment to do the water quality and simultaneously do the restoration,” said Bob Murphy, of the Alliance for the Chesapeake Bay. “A thousand acres is a lot to hand plant or restore in general.”