Researchers predict the Gulf of Mexico "dead zone," an underwater area with little or no oxygen, will be unusually large this year. But it's unknown how the oil spill will affect it.
Government-funded scientists expect a zone measuring 6,500 to 7,800 square miles — about the size of New Jersey.
Over the past five years, it's averaged 6,000 square miles.
The prediction comes from measurements of nutrient flows in the Mississippi River, which pours farm waste into the Gulf. Those nutrients stimulate excessive growth of algae that is broken down by oxygen-sucking bacteria.
University of Michigan ecologist Donald Scavia says the BP spill could make the dead zone larger because microbes gobble oxygen when consuming oil. But the effect could be offset if the oil limits algae growth.