Growing up on the west coast of Florida we would get red tides nearly every year. However, they continued to grow worse year by year. Like you pointed out, fertilizers seem to be the cause of them (lawn care is big deal
in FL)— and yes they were nasty. If you breathed with your mouth you would start coughing. If they were really bad, your eyes would begin to itch and sting practically blinding you. Also, I wonder if the BP oil spill has anything to do with this dead zone in the Gulf. That was a tragedy to the the coastal towns along the Gulf of Mexico. Luckily my hometown was spared, but many of us were worried about the pods of dolphins that migrate throughout the region.