millions of fish die, page-10

I can see that O2 deprivation could well explain it. The algae removes the oxygen, the fish start to die, then more oxygen is removed due to the rotting fish. Bit of a chain reation.

I hate to tell you this, but there is also a suggestion that such deoxygenation events could relate to climate change. See this article from only last year from the Scientific American. I'm not saying the jury is out, but it seems there could be a connection. Cooler water stores dissolved oxygen better than warmer water.

http://current.com/news/93056617_millions-of-fish-die-in-southern-california.htm

From the article: "climate models predict reductions in dissolved oxygen in all oceans as average global air and sea temperatures rise, and this may be the main driver of what is happening there".