"Red Tides" and Harmful Algal Blooms- This site is supported by the NSF, Woods Hole Oceanographic Institution and NOAA, and definitely is the place to start to learn more about Harmful Algal Blooms
North Carolina Aquatic Botany Laboratory- Check out the Pfiesteria piscicida page with links and information on the toxic dinoflagellate. NCSU was the first laboratory to identify this microorganism.