Monday, June 20, 2011

Noctiluca, the Night Light (Red Tide not)

This is the peak season for plankton blooms of certain species.  One is Noctiluca (night light) which colors the water like tomato soup.  Noctiluca is non-toxic but because of the term RED TIDE many people associate this with toxic plankton blooms known as HAB's or Harmful Algal Blooms. Noctiluca is a dinoflagellate that does not photosynthesize but preys on diatoms and other plankton.  There are two species of phytoplankton in our area that can be toxic but do not color the water.  If you collect some of the Noctiluca you can easily see the individuals with a hand lens and at night it will give of a flash of blue/green light when disturbed....or less often just randomly.  The light likely has some function.  In the Sea of Cortez I observed dolphins, sea lions and pelicans feeding on a dark night and they seemed to be keying in on the prey fish by following the glowing trail the fish made when swimming.  While dolphins and seals could use other clues to track a prey fish it is most likely that pelicans flying overhead could easily spot the light from the fish's wake......we were kayaking at the time as causing fish to swim away from the kayaks just by moving through the water.  So perhaps Noctiluca illuminates its predators allowing their predators to catch them and thus retucing the number of fish predators on Noctiluca. That would make Noctiluca very bright indeed. The biolumisence was so strong that the entire inside of the kayak was lighted by the flashing of the Noctiluca under the boats.  For more information visit:

Noctiluca Seahurst Park 6-17-11

Noctiluca (Night Light)