MIAMI BEACH  Under the cloak of nightfall, dozens of freshly hatched sea turtles beat tiny flippers against the wet sands of Miami Beach, inching their way toward the ocean and a life aquatic.

It is the first of many challenges these turtles will face in a lifetime that can exceed that of the average human.

Those female sea turtles that make it to maturity return every summer and fall to lay eggs of their own, in dozens of nests that each typically contain more than 50 eggs.

But the sea turtles’ way of life here is under increasing threat because they must share their breeding ground with throngs of beachgoers.