WASHINGTON -- With a new theory surfacing that toxic algae rather than asteroids killed the dinosaurs, scientists are still trying to unravel the mystery of what caused a massive algae bloom off the Northwest Coast that left thousands of seabirds dead and may have sickened some surfers and kayakers.

The bloom, which stretches roughly 300 miles from Newport, Ore., north to the Canadian border, still persists, though it's a shadow of its September and October peak.

Whipped by waves and storms, the microscopic phytoplankton, which had turned the ocean a rust color, broke apart, releasing toxins and creating a meringue-like foam that coated the feathers of birds like spilled oil. Up to 10,000 birds died of hypothermia in September, and researchers are still trying to come up with a count for October.

Researchers are also checking reports that surfers and kayakers who came in contact with the foam may have suffered cold-like symptoms, including temporary loss of smell and taste. The toxins also may have become aerosolized and affected beachcombers. In another strange twist, pathologists performing necropsies found that some of the birds lacked normal bacteria in their stomachs and other internal organs.

"It's definitely a warning sign of something," said Julia Parrish, a professor of aquatic and fishery sciences at the University of Washington. "We don't know what."