Warming Poses Threats To Chesapeake, Group Says

Yesterday's report also cited striped bass -- one of the bay's most beloved fish for food and sport -- as a creature under pressure from the heat. Foundation officials said the bass, also called rockfish, cannot tolerate water temperatures much above 76 degrees.

But when the water near the surface gets that hot, they sometimes cannot dive to cooler water because, as a result of the bay's existing pollution problems, there is often little oxygen at lower depths.

"It's like the old horror movies where the floor is rising, and the ceiling is lowering," Baker said. "They're getting squeezed."

Though many of yesterday's predictions were dire, scientists say it is exceedingly difficult to forecast exactly what the future will bring for a system as complex as the bay. Its health depends on a tangle of factors: development across the massive Chesapeake watershed, changes in temperature and rainfall, currents and winds that stir the water.

That makes it hard, for instance, to say precisely what will happen with the bay's dead zones. Foundation officials said yesterday that they believed hotter weather would make them worse.

Dave Jasinski, a water-quality analyst at the University of Maryland Center for Environmental Science, said climate change could cause changes across the bay and its watershed. "I don't know that anybody has any conclusive idea" what all the changes would add up to, he said.

Another problem laid out in the report is that as temperatures increase, global sea levels are expected to rise 7 to 23 inches by 2100. The rise is expected to be more severe in this area because land around the Chesapeake is slowly sinking, thanks to a complex geological process that began after the last Ice Age.

On low-lying Smith Island, in the Maryland section of the bay, waves are now just a quarter-mile away from the village of Rhodes Point, said Rick Edmund, the minister of Smith Island's three Methodist churches. He said residents are hoping Congress will approve a $9.4 million plan, proposed by Sen. Benjamin L. Cardin (D-Md.), to build artificial breakwaters offshore.

But Edmund said island residents know that their problems will probably get worse.

"Climate change," he said in a telephone interview yesterday, "will get us in the long run."