ATLANTIC CITY - The shuttering of four casino hotels this year has turned the iconic, three-mile-long Boardwalk into a patchwork of large abandoned buildings alongside businesses determined to survive.

And with the potential closing of a fifth, the Trump Taj Mahal, later this year, the challenge for Atlantic City is how to keep the Boardwalk vibrant.

"The economy dictates what occurs," John Palmieri, executive director of the Casino Reinvestment Development Authority, said at a recent business forum. "We can't force the issue when we're dealing with a lot more competition within a couple of hours' drive. We're making those adjustments and trying to look at broadening the base - diversifying the base. We're still a tourism destination and hospitality-oriented economy. But we're not just solely a gaming economy anymore."

The CRDA, which uses gambling proceeds for redevelopment projects, has added more than $200 million in Boardwalk improvements since 2011 - including five dozen "ambassadors" to assist tourists, casino-facade projects, new lighting, and additional police.

But casino closings have made many here - including noncasino businesses on and near the Boardwalk - very nervous, with their own livelihoods at stake as the famed walkway continues to bleed not only gaming revenue, but also visitors.

"It's definitely hurting business," said Kerry Celepija, 33, who works at Phillips Seafood, a restaurant at the Pier at Caesars, a mall connected to Caesars casino on the 50-yard line of the Boardwalk. "I see it in the number of people coming to our restaurant.

"There's not as many people visiting because they think all the casinos are closing," Celepija said, "and not realize the others are still open."

Atlantic Club, on the southern end of the Boardwalk, closed in mid-January; Showboat and Revel on the northern end shut down over Labor Day weekend; and Trump Plaza, in the center next to Boardwalk Hall, shut its doors Sept. 16.

While city and tourism officials, including Mayor Don Guardian, are hoping the Taj continues to operate, to save nearly 3,000 jobs, the economic signs point in all likelihood to its closing. That would leave four casinos operating on the Boardwalk and three in the Marina District.

Billionaire Carl Icahn, who owns the first lien debt on the Taj and has been angling for concessions from the casino union, Unite Here Local 54, and the city and state to keep it open, said Oct. 23 that he believed the casino "will almost certainly close." Icahn said the casino could close as early as next month.

Israel Posner, executive director of the Lloyd D. Levenson Institute of Gaming, Hospitality, and Tourism at Richard Stockton College, said Atlantic City was closely identified with the Boardwalk - and explained why its image was crucial.

"Our research has shown that more than 80 percent of the expected 25 million visits to Atlantic City this year will include the Boardwalk, the most iconic beach promenade in the country," Posner said. "Since the Boardwalk is such a frequent feature of an Atlantic City visit, the overall visitor experience is obviously critical to the success of the tourism district."

Another closed casino could impede something else. The Taj Mahal has 2,012 rooms that will go dark if the casino folds after Nov. 30 - no minor issue, since the city is aggressively going after convention business. The closure will bring the number of casino rooms lost this year to 5,500 - nearly a third of the city's 18,500-room inventory, half of them on the Boardwalk.

Posner said his research has shown that the majority of Atlantic City's 12 million overnight visitors stayed at a Boardwalk casino hotel.

"A reduction of about 50 percent of Boardwalk room inventory," he said, "will have a significant impact on availability, occupancy rate, and pricing of Boardwalk lodging."

The privately owned Evo Restaurant & Lounge is in the Trump Plaza, but it has its own Boardwalk entrance. It is one of three restaurants attached to the now-closed casino that have stayed open. The others are Rainforest Cafe and Nathan's Famous.

Trump Plaza gamblers would use their player cards and "comps," or freebie points, at Evo for food, said manager Maria Boteze.

"We can't count on the business we got from them," she said. Trump Plaza "was slow, too, but we still got something."

She said additional casino closings would increase concerns of how to keep the Boardwalk viable and healthy, especially during the slow winter months, when it gets dark much earlier.

"From November, you can't really expect huge traffic on the Boardwalk," Boteze said. "Unless there's a big event at Boardwalk Hall. Then we're packed.

"The whole city is slow. It's like a ghost town," she said. "With all the casinos closing in Atlantic City, and new casinos opening elsewhere, like Philly and New York, they hurt all businesses here in general."

Palmieri said recently that he and other city leaders were hoping against hope that the Taj and others made it.

"Of course, we don't want to see any casinos close," he said. "We want them all to make a buck. ... But competitive factors won't allow that."

Guardian said the market would determine how many casinos stayed open in Atlantic City.

But "it's very tough to have another property close," he said. "You have 3,000 people depending on the Taj. It will be devastating."

The city is seeking solutions to halt the casino closings, but will not bow to pressure for concessions such as $30 million in property-tax breaks for Icahn and Trump Entertainment Resorts Inc., which owns the Taj and the former Trump Plaza. In Trenton, State Senate President Stephen Sweeney (D., Gloucester) has also vowed not to help Icahn with state aid.

"You can't keep going to the trough," Guardian said. "At some point, you have to man up and pay your taxes."

Gov. Christie plans to visit the resort again Wednesday, for the second day of his Atlantic City summit to collect ideas from state lawmakers, city leaders, and casino officials on how to turn the city around. His first meeting was Sept. 8.

"Time will heal us," Guardian said, "and we will come out of this."

He cited the success of last summer's free beach concerts as what the city needs more of to become an entertainment destination.

Bass Pro Shops will debut in the spring as "an entertainment venue in itself, which attracts a million people a year," he said.

As part of its strategy to woo a new type of visitor, the mayor said, the Atlantic City Convention and Visitors Authority has tripled its sales staff to 26 to go after midweek conventions. The $126 million Harrah's Conference Center opens in August in the Marina District to help lure them in. So far, 25 contracts have been signed to use the new center.

"We definitely see a major expansion in conventions and conferences," Guardian said, "as a way to grow beyond gaming."

sparmley@phillynews.com 856-779-3928 @SuzParmley