With ocean currents, winds, and weather the powers behind the movements of the sprawling oil slick created by the Deepwater Horizon disaster, personnel at national parks along the Gulf Coast can only watch, wait, and prepare for the worst.

Crews at Gulf Islands National Seashore by Sunday night had completed installing mechanical booms around their 11 barrier islands and had little to do but pick up litter and make baseline assessments of conditions along their sparkling beaches. On Tuesday, two weeks after the Deepwater Horizon was rocked by an explosion and ensuing fire that killed 11 and resulted in the deep-water drilling rig's sinking, not a sign of oil had been spotted anywhere within Gulf Islands, spokeswoman Jody Lyle said Tuesday evening; not on any beach, not on any wildlife that crept, swam, or flew into the park.

Crews were ready, though, to respond if any sign of oily impacts were noted, said Ms. Lyle.

By Monday, teams were being assembled in south Florida to begin making similar baseline assessments along the coastlines of De Soto National Memorial, Big Cypress National Preserve, Everglades National Park, Dry Tortugas National Park, and Biscayne National Park.

“This is literally day two," Park Service spokesman Larry Perez said Tuesday evening, adding that by end of day Wednesday managers planned to have the coordination and strategies in place for completing the baseline assessments at the five park units. "Park by park, it can be done pretty efficiently," he said.

While calmer waters and improved weather of recent days in the Gulf of Mexico seemingly had slowed the growth and spread of the oil slick, Park Service officials have been told that it's only a matter of time before the "Loop Current," as the warm arm of the Gulf Stream that swings through the gulf is known, carries the oil down along the western coast of Florida, through the Straits of Florida and into the Atlantic.

As of Tuesday night, meteorologist Dr. Jeff Masters, who writes a blog for Weather Underground, noted that "(T)he only areas at risk of land-falling oil over the next five days will be the mouth of the Mississippi River in Louisiana, and the Chandeleur Islands. The latest forecast of Gulf currents from the NOAA HYCOM model show weak ocean currents affecting the region during the remainder of the week. These currents will not be strong enough to push any oil southwards into the Loop Current over the next five days, so the Keys and South Florida are safe from oil for now."

If the oil hitches a ride on the Loop Current, it could be devastating to more than national park beaches. Dry Tortugas National Park, for example, lays claim to the Research Natural Area, which covers 46 square miles and complements the Tortugas Ecological Reserve. While the ecological reserve is in deeper water, the natural area is more shallow and valuable as a nursery grounds for many fish species. Oil contamination to this area could gravely impact the nurseries.

But the currents of the Gulf Stream can be unpredictable at times, according to William "Buzz" Botts, the education coordinator at Padre Island National Seashore. While that seashore is about 450 miles west of the Deepwater Horizon site, Mr. Botts said Tuesday that officials at the seashore were keeping an eye on the currents.

“If you really get into the nitty-gritty of how the currents in the Gulf work, that (Deepwater Horizon) well is in a location where it could ultimately affect us, just depending on how the currents change," he said. "They do shift around over the course of the year quite a bit and so it’s possible we're going to see some effects. But at this point the odds of it hitting us, it’s going to be significantly less than it would be over to the east, Gulf Islands National Seashore. They've really got their hands full.”

One of the tricky things about the Loop Current, explained Mr. Botts, is that it can spin off currents to the west as well as the east.

“The Loop Current, that is the dominant current in the eastern part of the gulf and ultimately exits out of the Florida Straits. That’s the one that everybody’s a little concerned with because of the way it could potentially transport that oil down the Florida Gulf Coast and then out into the Atlantic and up the East Coast," he said. "If you really get into the studying those currents, it’s amazing how they shift and how they can change and how deep they run.

"That Loop Current, it’s powerful enough to be felt 2,500 feet under the surface, so it is a big current, 80, 90 miles across. But periodically, the thing that concerns us, about every six to 11 months it stretches northward up toward the area where that well blew out and then it will break loose," continued Mr. Botts. "It gets so stretched that a big eddy kind of snaps off of it, and once that happens it moves westward along the Gulf. ... That's one of the reasons it’s so closely monitored. They try to monitor when those eddies are going to break loose and start drifting westward, and that to me is the scenario that could potentially move some of that oil into our area.”

It was yet another Gulf current, the Yucatan Current, that did damage to Padre Island back in June 1979 when the IXTOC I exploratory well in Mexico's Bay of Campeche blew out and spewed oil into the Gulf for nine months. The current carried the oil all the way to Padre Island, where it coated the beaches, according to Mr. Botts.

“The whole story is going to be interesting to watch it play out. I don’t know what ultimately it’s going to mean for all the Gulf Coast beaches," he said. "I guess it’s all dependent on how long the well flows, how much it continues to pour out. But ITOC, down in Mexico in '79, certainly when you read about it, just even a basic overview of it on Wikipedia or something like that, it’s remarkable how similar the two accidents are.”