Date:  Thu, 14 Jun 2001 14:29:44 -0700 (PDT)
From:   Peter Franks <>
Subject:   Red Tide (look out your window...)
Hi Folks,

There's a reasonably dense red tide growing off the pier. It's been
chugging along for a while, but it became visible (to me at least)
yesterday. From what I can tell, one of the dominant species is
Lingulodinium polyedrum, a bioluminescent dinoflagellate (in
layman's terms, a cute little single cell with a flagellum that
makes its own light). This means that we might have a nice light
show tonight, and in subsequent days if the weather remains nice.

Here's what you should do: get a clear glass jar or bottle and take
a sample of the water from the beach (or as far offshore as a friendly
neighborhood surfer will take one for you). Take it home, and put it
in a cool, dark place (your bathroom would be ideal). After the sun
has gone down, lock yourself in the bathroom or closet with the lights
off, and give your eyes time to adjust to the darkness. Then give the
bottle a swirl. With any luck, you'll see one of nature's most beautiful
light shows.

What's happening: the dinoflagellates have little bags of chemicals that
mix when the cells are disturbed, creating a chemical flash of light.
Ask Mike Latz (our resident expert on this) for more details if you're

Why wait until dark? The cells have a natural rhythm to their light
production cycle - why make light when the sun's out? They will only
make light (bioluminesce) when the sun has gone down.

Are they toxic? No. We tend not to get blooms of toxic phytoplankton
here in the Southern California Bight. But there's always next time...

How long will the bloom last? Depends on the weather. A few cloudy, windy
days will tend to make the bloom dissipate. As long as the weather is
sunny and calm, we could see the bloom for several weeks.

Why can't I see it in the water? The cells tend to migrate to the surface
of the ocean around noon, and go back deeper in the water in the evening.
Your best chance to see the red tide (it's actually brownish) is around
noon. Climb the hill and look from the aquarium or the library to get
the best view of the brown bands. Wear polarized sunglasses if you have
them to cut the glare from the water.

Why do the organisms form bands parallel to shore? The cells can swim
a bit, and interact with the flows of the water driven by other forcings.
The bands of brown water are high concentrations of cells which have
accumulated in the troughs of internal waves. These waves are like
surface waves, but are much slower, and much larger in amplitude. If
you sit and watch long enough (an hour), you should see the bands move
with the waves (usually onshore). There are also patterns formed around
the pier through interaction with the rip currents. For more on this
subject, take my course in physical-biological interactions!

Please let me know if your bioluminescence experiments work.

Cheers, Peter Franks