Park rangers discovered 20 ``tar balls'' on a Key West shore, prompting alarm Tuesday that the first sign of the massive BP oil spill had washed up on a Florida shore.
In Key West, the Coast Guard urged calm and sent samples of the three- to eight-inch flattened tar balls to a lab in Groton, Conn., to determine whether they had come from the massive leak in the Gulf of Mexico or perhaps oil remnants from a passing ship.
A Coast Guard spokeswoman, Lt. j.g. Anna K. Dixon, cautioned from Key West: ``There is no proof or reason to believe these tar balls are from the Gulf at this point.''
Analysis of the tar balls' origins would not be complete before day's end, she said, adding that the samples had been sent by overnight delivery.
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She could not say the last time a concentration of 20 tar balls was found in Key West on a single day. The Coast Guard was sending searchers out -- by land and air -- to scout for more tar on Tuesday.
Florida tourism officials also sought to downplay the discovery, noting that all Sunshine State tourist attractions were still open for business, the beaches included.
A state advisory noted that, just last year there were 681 reports of ``oil and petroleum incidents along Florida's waterways and beaches,'' advising ``these types of occurrences are not as unusual as one might think.''
Still, the spill was having an increasing impact on the fishing industry.
NOAA Administrator Jane Lubchenco said in a conference call Tuesday morning that the National Oceanic and Atmospheric Association was expanding its fishery closure at noon to cover 19 percent of the Gulf, or 45,728 square miles.
The tar ball discovery stirred alarm in the tourist industry and increased activism among environmentalists, who want the coastline cleaned up of debris quickly in case any more tar arrives.
``I woke up this morning and thought: `Oh my god,' '' said Sarah Notch, president of the Key West Attractions Association and general manager of the Pirate Soul Museum in Key West.
For Notch, reports of nearly two dozen tar balls washing up on one of Key West's most popular attractions dramatically upped the stakes in an oil spill that had seemed threatening but still far away.
A pristine beach is Fort Zachary Taylor State Park's main selling point. The recorded message that greets callers states: ``If you're looking for Key West's best beach, you've found it.''
Keys environmentalists, meantime, put out a call to volunteers to sign up for a section of the shoreline and clean up debris through the Green Living Energy Education nonprofit.
Volunteers are trained to not touch any hazardous materials -- tar balls chief among them -- and alert authorities while clearing out more typical shoreline litter.
``We're mobilized,'' said Alison Higgins, president of GLEE and land conservation program manager for the Nature Conservancy in Key West.
At the www.keysspill.com website, she said, GLEE has assembled information regarding local clean-up opportunities as well as divvied up the shore in a Coastwatch map.
By Tuesday morning, with word of the tar ball discovery, she said, trained volunteers had signed up for the first 55 of 300 squares on their Coastwatch grid.
Park rangers at Fort Zachary Taylor and the adjacent Navy beach at Truman Annex in Key West discovered the tar balls throughout the day Monday, according to a Coast Guard statement, and alerted pollution control experts about 5:15 p.m.
The heaviest concentration was found at high tide, about 12:30 p.m.
More surveys were planned for Tuesday morning with participation of the Coast Guard, National Oceanic and Atmospheric Administration and Florida Keys National Marine Sanctuaries. The Coast Guard also said it would send a helicopter ``with a trained pollution investigator on board'' to do more searches.
Higgins, the environmentalist, said in her 15 years in the Keys she had never heard of 20 tar balls turning up on the coast in a single day.
Asked whether she thought it was BP spill oil, she replied: ``It seems highly probable. But it doesn't really matter because we still need to do the same things'' in terms of coastal cleanup, regardless of the waste's origins.
The timing of the discovery amid national concern over the BP spill, ``just ups the ante about how important it is,'' she said.
In Washington Monday, a top Interior official charged with overseeing oil and gas drilling resigned, and Homeland Security Secretary Janet Napolitano defended the administration's handling of the emergency at the same time she said it was largely dependent on BP to respond to the crisis.
Chris Oynes, who had overseen oil and gas leasing in the Gulf of Mexico for 12 years before being promoted to Mineral Management Services associate director for offshore energy and minerals management, sent a letter of resignation effective May 31. Oynes has come under fire for being too close to the industry officials he regulated.
Meanwhile, BP announced it was awarding tourism grants to the governors of Florida, Alabama, Mississippi and Louisiana to help promote tourism over the coming months, in the wake of the Deepwater Horizon spill.
BP said it would give $25 million to Florida and $15 million each to Alabama, Mississippi and Louisiana.
Florida Gov. Charlie Crist said he would use the funds ``to spread the word that Florida's beaches are clean, our fish are biting, and the Sunshine State is open for business.''
Miami Herald staff writers Daniel Chang, Curtis Morgan and Toluse Olorunnipa contributed to this report