By Brian Skoloff and John Flesher
GULFPORT, Miss. -- The gigantic Gulf of Mexico oil spill is the latest blow to a unique marine environment already fragile after decades of human encroachment and natural upheavals - at a time of year when some of its most vulnerable species are nurturing their young.
A watery expanse of 600,000 square miles, the Gulf features marshes and coral reefs, commercial and recreational fisheries and hundreds of wildlife species, including imperiled birds, whales and sea turtles. Many are in harm's way, as the oil unleashed when an offshore rig exploded two weeks ago threatens their food supply and the marshlands where they spawn or build nests.
The spill "could not have come at a worse time," said Carole Allen, Gulf director of the non-profit Sea Turtle Restoration Project.
It's too early to know how extensively the waters and wetlands could be damaged or how badly any particular species - even those listed as endangered - could suffer, scientists say. Although 30 dead sea turtles had turned up on Mississppi beaches in recent days, necropsies completed on five showed no evidence that oil killed them.
Still, biologists who study the region's birds and fish are worried.
"You hear that noise?" Mark LaSalle, director of the Pascagoula River Audubon Center near Biloxi, asked recently while strolling on the beach wearing the bird-watcher's trademark gear, a button down khaki shirt with binoculars slung around his neck. His voice was practically drowned out by the whistling and chirping of several thousand endangered seabirds known as least terns, nesting on the beach. The Gulfport area has one of the country's largest nesting colonies.
"Look at those gray dots," LaSalle said, pointing down about a mile-long stretch of sand. "There's probably 1,000 birds right there.
"If the oil comes onto the beach, it'll hit the eggs and they'll be gone," he said. "And if the fish disappear, they'll starve."
Up to 5,000 bottlenose dolphins may be calving in the path of the slick, said Moby Solangi, director of the Institute for Marine Mammal Studies in Gulfport.
"During calving season, these animals move from deeper to shallow waters to give protection to their young," Solangi said. "These animals are going to go in and out of the spill just for curiosity."
Larry Schweiger, president and CEO of the National Wildlife Federation, said Monday there was a large number of dead jellyfish along the coast of an island at the mouth of the Mississippi River.
"You occasionally see dead jellyfish anytime you have high winds, but this was far beyond the normal," Schweiger said.
Young shrimp, popular with diners and a key part of the marine food chain, are preparing to migrate from estuaries to open waters "in the midst of the oil being pushed into onshore areas," said Chris Dorsett, director of Ocean Conservancy's fish conservation and management in Austin, Texas.
The Gulf, bordered by the United States, Mexico and Cuba, also supports endangered birds such as the snowy plover, as well as the formerly listed brown pelican.
The area between Louisiana and Florida is "some of the most biologically varied marine habitat in the country," said Bill Hawkins, director of the Gulf Coast Research Laboratory in Ocean Springs, one of many scientific outposts along the coast where staffers are anxiously monitoring waters in the advancing oil plume.
Warm temperatures extend breeding seasons for fish and other marine creatures, while coastal waters, marshy bottomlands and nutrient-rich estuaries yield abundant vegetation, providing spawning grounds and food for an incredibly complex food web.