the fact that the red tide washed in at the same time the Crimson Tide is coming in just makes for an ironic little story for the local papers t write up. Truth be known though red tide is very common out there. When I lived in Cocoa Beach it was a fairly frequent occurance.
As far as it's effects on humans, I've had a little bit of exposure to it and it felt about like being at the other end of a large room where someone was pepper sprayed. Don't ask me how I know that either. :| It's not too terribly bad if you're not right there in the middle of it, though it could cause some degree of irritation depending on the person.