The state's annual oyster survey being conducted this month likely will show how Hurricane Irene and Tropical Storm Lee have affected the Chesapeake Bay's oyster population.

The Department of Natural Resources survey last year showed the highest level of spat, or baby oysters, since 1997, with the heaviest counts in the southern Eastern Shore waters. But Irene and Lee brought the third highest deluge of water at the Conowingo Dam, which forced engineers to open 44 of 53 gates.

Opening those gates brought a rush of debris, fresh water and sediment down the Susquehanna River and into the Chesapeake Bay.

When the mess made its way down the Bay last month, it nearly put a stop to commercial crabbing in the Upper Bay. Watermen now are asking the DNR for an extension of the season.

Unlike crabs, oysters can't escape the storm surge. The bivalves can go dormant for about 10 days, essentially holding their breath, but then draw a deep breath.

"That could be a problem if the Bay hasn't cleaned up some," said Del. Jay Jacobs, a former watermen whose district includes Cecil and Queen Anne's County. "This many days of muddy water could kill these oysters for three or four years."

Sediment also is a problem, burying oysters and smothering spat in silt.

"The big problem is scrubbing," said Bob Wood, who works for the National Oceanic and Atmospheric Administration as director of Cooperative Oxford Lab. "We reached levels of flow that will scrub sediments from behind the Conowingo Dam. With oysters, the primary worry will be burial."

Jim Mullin, executive director of the Maryland Oystermen Association, also is worried oyster bars could silt over.

"That's the number one issue we're keeping an eye on," he said.

Most of the oyster industry is concentrated in the Lower Bay, and Mullin said the sediment could dissolve before it reaches that area. Talbot County Watermen's Association President Bunky Chance also said he hopes the sediment dissolves before it reaches the Lower Bay.

But salinity also is a problem oysters don't like freshwater.

"If salinity levels fall below three parts per thousand for a long time, oysters can die from a lack of salt," said Chris Dungan, an oyster disease research scientist with DNR. "Some places off the mouth of the Choptank are below 3 ppt on the surface, but bottom measurements saltier water is dense and stays near the bottom are quite a bit higher. So that's good news for the oysters."

Those lower salinity levels also could limit protozoan diseases that plague oysters, particularly MSX.

"When we do a disease analysis in the fall survey we fully anticipate seeing a significant reduction in MSX presence," Dungan said. "And probably Dermo disease may show a similar decrease."

Scientists also will monitor contamination brought from the surge of sediments, along with nutrients, that could contribute to dead zones, Wood said.

"The good news is the (storm came) at the end of the summer, so there are probably not a lot of fertilizers on the surface ready to roll into the Bay," he said. "As long as burial isn't a giant issue, we may have dodged the biggest bullet.