Florida Growth Pressures Wildlife. ENDANGERED SPECIES

ONE more manatee - graceful, slow-motion sea cow of shallow Florida waters - was recently found badly injured by a boat propeller. Rescuers dubbed him Walter Payton because of his deft evasion of the seven boats and a helicopter that eventually picked him up.

But as man continues to crowd into Florida, the endangered manatee is harder pressed to avoid propeller blades while seeking disappearing sea-grass beds for grazing. Forty-three manatees were killed by boats last year, twice as many as were killed annually during the early 1980s.

In one of the nation's fastest-growing states, the zeal for city building is squeezing a watery and delicate natural environment. And the manatee is not the only species under pressure here:

In the lower Florida Keys, only 250 to 300 endangered Key deer remain. About 50 of the friendly, two-foot-high animals are killed by cars every year.

As housing developments and strip malls bring heavier traffic to Big Pine Key, a new road has been proposed near the Key deer refuge there. Conservationists fear the road would kill more deer.

The Florida panther has a much weaker hold on survival. Between 20 and 50 of the cats remain, ranging southern and central Florida. Highway traffic across the Everglades remains a major threat to the nearly extinct animal. The biggest problem, according to state researchers, is the loss of panther habitat to subdivisions, citrus groves, and other development. Biologists plan to breed the panther in captivity to help propagate the species.

The endangered Ridley sea turtle has been dying in shrimpers' nets in suddenly higher numbers over the past year. About 70 Ridley turtles washed up dead on Florida's Atlantic coast between 1980 and 1986. But during the past year, 44 dead turtles were found, most of them killed in shrimpers' nets.

State officials are now considering requiring shrimpers to use turtle-excluder devices immediately - rather than waiting until federal requirements take effect later this year and next year.

While the once-endangered alligator has become a thriving conservation success story, his shy saltwater cousin, the American crocodile, remains endangered. Crocodiles once nested in the mangrove swamps of what is now Miami Beach. Urbanization has driven them to the southern tip of the state. About 300 remain.

The endangered wood stork has virtually disappeared from south Florida because the canals that drain water from the Everglades have drastically shortened the wet season there. Without more extensive drainage, the stork population may hold steady in central and north Florida.

Many of these species have adapted to the presence of man, especially by moving north into more temperate zones. Man is increasingly making allowances for them, although the pressures of urbanization continue to build.

At least 1,200 manatees still survive, Florida researchers say. But more people than that move into the state in any two days.

``It doesn't take a real genius to figure that the problems they face today are going to multiply in the future,'' says Richard Frohlich, a marine mammal biologist with Florida's Department of Natural Resources.

How the manatees fare depends largely on success in maintaining the environmental quality of Florida's bays and rivers.

When hunting was the major threat to species, as it was with the alligator, solutions came easier.

The Key deer population is an example of a success story gone sour, says Deborah Holle, director of the National Key Deer Refuge. In 1954, the deer had been hunted down to less than 50 in number. The herd replenished itself to a stable 400 in the 1970s, but began dropping again.

``The hunting was easily corrected,'' she notes. ``But development is more insidious.''