Mesoscale eddies spun off from the Gulf Stream are powerful, roaming engines of ocean productivity. As they peel away from the North American coast, these swirling currents haul nutrient-rich water and microbial life into the nutrient-starved North Atlantic Subtropical Gyre, triggering bursts of plankton growth and carbon uptake. Crucially, they also transport nitrogen-fixing microbes that manufacture new usable nitrogen from the atmosphere, allowing productivity to surge even after initial nutrients are exhausted—sometimes pushing nitrogen fixation rates to more than an order of magnitude above surrounding waters. This project will track individual eddies across their full life cycle using AI, satellites, autonomous vehicles, and microbiology tools to reveal how their physics and biology work together over months at sea.