NEW ORLEANS (AP) — Scientists say this year's Gulf of Mexico "dead zone" is the eighth largest on record.

Every summer, a large underwater area with too little oxygen to sustain marine life forms off Louisiana.

Scientists had predicted a near-record 7,800 square miles (20,200 square kilometers) this year because of nitrogen and other nutrients carried by Midwestern flooding. However, this year's research cruise measured it at 6,950 square miles (18,000 square kilometers).

Scientists say the main reason is that waves from Hurricane Barry had mixed oxygen into the water.

The dead zone forms as the nutrients feed algae blooms, which die and then decompose on the sea floor. That uses up oxygen, starting at the bottom.

Hurricane Barry made landfall July 13 — 10 days before the measurement cruise began.