Biologists are also worried about the oyster population. One of the most significant indicators will be how the beds of Bay grasses hold up after being hammered for three out of four years by abnormally high flows and the associated nutrients and sediment. The near record spring flows of 1993 and 1994 have been blamed for two straight years of declines in the acreage of Bay grasses. After reaching a 12-year high of 73,081 acres in 1993, grass beds fell to 59,894 acres last year. The grasses, known as submerged aquatic vegetation, are not only important to the Bay ecosystem, but are considered leading water quality indicators.
Grasses require sunlight to grow, but sediment in the runoff clouds the water.
Also, nutrients cause algae blooms, which can block light to grasses and spur growth of tiny parasites on the grasses that also block sunlight. Grasses are important to the Bay because they provide food for some species, such as ducks, and habitat for others, such as blue crabs and juvenile fish. Robert Orth, a scientist at the Virginia Institute of Marine Science who conducts an annual Baywide survey of grass beds, said no clear picture of this year's situation has emerged. While beds in the middle part of the Bay have been hard hit, he said, those in the Eastern Bay and Choptank River, as well as in many Western Shore rivers, appear to have held up well so far.