In Florida, Mickey Mouse is a tourist-industry tycoon

Mickey Mouse may be a small, unassuming character, but his influence on the Florida attractions business makes him the mouse that roars. Since Walt Disney World opened near Orlando in 1971, Florida's tourist attraction business has catapulted from largely ''mom and pop'' businesses to competition among corporate giants.

Central Florida has become dotted with all kinds of ''worlds'' and ''gardens'' and ''halls of fame'' that are competing for the spinoff from the Disney traffic, and the smaller aquariums, alligator lands, and jungle gardens have had to adjust to the changing market or close their doors.

South Florida tourist businesses, especially Miami Beach hotels, have complained that Interstate 4 across central Florida, along which most of the new tourist attractions have been built, has become a ''Great Wall of Florida,'' stopping tourists from getting any farther south.

Many Miami Beach hotel owners sought to introduce casino gambling to lure people past the family-oriented central Florida tourist attractions, but the state's voters turned the proposal down in a referendum.

Central Florida attractions have competed with each other by creating what they hope are more exciting rides and sights to get people in through their doors. Sea World may put in a new whale stadium to compete with Busch Gardens's new roller coaster, and Circus World's new owners promise to invest millions of dollars in new rides, perhaps to draw people from Cypress Gardens's new ''Island in the Sky,'' ride.

Mickey Mouse one-upped them all in October 1982 when Disney World opened its Experimental Prototype Community of Tomorrow (EPCOT), which provides a tourist with a couple of more days of entertainment.

The Florida attractions business appears to be reaching maturity, some of its executives say, and the competition for new rides and exhibits may slacken as companies who run the fantasies take a closer look at what the bottom line can bear.

''There has been such a proliferation of attractions in Florida, especially between Tampa and Orlando (that) there are now so many things to do it is impossible for people to do them all,'' says Steve Rodgers, editor of Attractions Business Magazine. ''Some of the small ones are dropping out. Even some of the large ones are showing a moderate decline since the opening of EPCOT. There's too much to see and too much to do.''

Before Disney, there wasn't much reason for a tourist to come to central Florida. Busch Gardens was the state's largest attraction, and it was run mostly as an advertisement for Anheuser-Busch beer. Cypress Gardens was the granddaddy attraction, and it featured mostly a botanical garden and a water ski show. But the people who run those original attractions are not unhappy that Mickey Mouse chose to come to central Florida.

''The greatest thing that ever happened to Florida is that Disney decided to build here,'' says William Sims, Cypress Gardens executive vice-president. ''It worked as a magnet to bring tourists to this area, and it has created the unusual situation of having more attractions here than anywhere else.''

Thom Stork, marketing director for Busch Gardens, says that when Disney World opened, ''the group running Busch Gardens said, 'Let's take a look at what's happening with Disney.' They asked the (Anheuser-Busch) board of directors for money and turned the place into a theme park.''

Since then, Sea World, Circus World, the Stars Hall of Fame, and even the federal government's Kennedy Space Center have sprung up from the orange groves and cypress swamps to become major tourist attractions.

Twenty-three million people went through Disney World's gates the year after EPCOT opened, and the other attractions have scrambled to lure those people as they came out and looked for something else to do.

But the benefits of continual expansion may have reached their peak.

''Always expanding means higher admission prices, which could bring us under the law of diminishing returns,'' Mr. Stork says.

''It was easy a few years back to put in a $6 million roller coaster, but now we have to question whether the gate can handle a $1 increase in the admission charge to pay for it.''

And deciding what the public will pay to see has become a science for business school graduates, he said.

''There's a change in the tourists, and a lot has to do with economics,'' Stork says.

''If we are going through a strong recession, people are more likely to want to fantasize. When times get better, they seem to want more participatory attractions.''

That means water parks are the rage in Florida now, he says, and the theater attractions are less popular. But what will happen in the future?

Amusement Business Magazine's Rodgers predicts some of the attractions will fail. The number of people attending some of them is down, he said, and those attractions won't have the money to build the new rides that will draw larger crowds.

''The heyday is gone,'' he said. ''I don't pack up the car every season and head for Florida like my parents did.''

But his gloomy outlook is not shared by others.

''For the future we're going to continue to grow,'' says Disney's Charlie Ridgeway.

''If it turns out the industry has matured, then we still have a healthy level of visitors. We'll never stand still.''

Stork of Busch Gardens says the attractions will try to streamline and improve their parks using the rides and events they now have so they can provide better shows without a large investment.

Cypress Gardens's Sims also sees growth in the future for existing attractions, but he doubts that any new, major theme parks will be built.

''I don't expect any of the large parks to fold, but the number of attractions competing for the visitor now will be the same in five years,'' he said. ''In today's dollars, to open a major park, you're talking about a considerable capital investment.''