A new study suggests that much of the islands that line South Florida's southern tip could lose much of their land mass. [...] 'South Florida is on the front line against sea-level rise in the United States, and the Florida Keys are ground zero,'' Evan Flugman, who co-authored a Florida International University study told The Herald. The discovery was made by accident. As treasure seekers canvassed the Florida Straits they discovered buried land just 35 miles from Key West. There, 45 feet below the surface, they discovered dense mud with well-preserved mangoes, pine cones and pine tree pieces. The shoreline could date back to 8,500 years. 'Looking at it, I was thinking: `Wow, this could be the shoreline of Big Pine Key,' '' said Corey Malcom, director of archaeology for the Mel Fisher Maritime Heritage Society. [...]