Algae blooms naturally in lakes, rivers and ponds, and in the ocean, often along coastlines. What scientists say they don't know is what triggers massive blooms like the one seen recently in Qingdao, China - or why some blooms are harmful or toxic while others are not. To learn more about toxic algae, we spent a day in the Mid-Atlantic U.S. State of Maryland with research scientist Celia Dawson. VOA's Paul Sisco reports.
