By Craig Welch
Seattle Times environment reporter
The mysterious bird-killing algae that coated Washington's ocean beaches this fall with slimy foam was the biggest and longest-lasting harmful algal bloom to hit the Northwest coast.
Now the phenomenon that killed at least 10,000 seabirds — more than any known event of its kind — has scientists consumed by questions: Was it a rogue occurrence, rarely if ever to be repeated, or a sign of some fundamental marine-world shift?
And did we cause it?
Answers may come slowly. "You can think of it as a jigsaw puzzle with 500 pieces, but we only have about 50," said Julia Parrish, a University of Washington fisheries and oceans professor.
This much is known: Toxic blooms of microscopic phytoplankton sometimes called red tides are exploding worldwide, even along pristine waters like the Northwest coast.
And the organisms behind these blooms can behave unpredictably, revealing how little we know about the sea.