Nancy Rabalais: The "dead zone" of the Gulf of Mexico

Ocean expert Nancy Rabalais tracks the ominously named "dead zone" in the Gulf of Mexico — where there isn't enough oxygen in the water to support life. The Gulf has the second largest dead zone in the world; on top of killing fish and crustaceans, it's also killing fisheries in these waters. Rabalais tells us about what's causing it — and how we can reverse its harmful effects and restore one of America's natural treasures.