Lights…cameras…plankton!

by Amanda Kahn

You decide to go out for a walk at the beach at night.  You’re far from civilization and the moon hasn’t risen yet, so the only light you have is starlight.  As you approach the beach, however, you notice more sparkles than just the stars in the sky.  The waves seem internally illuminated as they crash on the beach, but surely that’s just the reflection of the stars.  As you walk onto the wet sand, you are startled to realize that it seems to be illuminated too!  Every footstep incites a blue glow that pulses, then fades away in a million tiny sparkles.

Things to ease your mind:

  1. Vampires don’t sparkle.  Don’t even go there…you are not a sparkly vampire and just didn’t realize it.
  2. You are not crazy (even if you do like sparkly vampires).
  3. What you’re seeing is natural–not some toxic sludge or man-made chemicals.
Gippsland Lake, January 2013

Fears allayed, but what’s going on then? Credit: Phil Hart

What is causing that glow is bioluminescence, or light produced by biological organisms.  Bioluminescence is found in all kinds of animals–fish, squid, pyrosomes, and jellies, to name a few–but the glowing water you see above is a result of a red tide.  Red tides often have negative connotations, and for good reason.  Some red tides are toxic and lead to harmful, though naturally produced, compounds.  Filter feeders such as mussels and clams concentrate the toxins during bad red tides, leading to paralytic shellfish poisoning and diarrhetic shellfish poisoning in animals and humans that eat them.  Dinoflagellate blooms are not responsible for outbreaks of domoic acid poisoning, also called amnesic shellfish poisoning–that is caused by blooms of planktonic diatoms (algae) called Pseudo-nitzschia.  In the video clip below of a red tide in San Diego, check out images of what a red tide looks like during the day AND at night, in case you, like me, are not right by the ocean at the moment.

In Bamfield, you can get great views of bioluminescence on the beach and in the waves at Pachena Beach.  Or, if you’re keeping a rigid schedule in the lab and cannot make it out to the beach, you can go down to the foreshore and grab a bucket of water from off the docks (wear a life vest!).  Drop a rock in the water, put your hand in the bucket and wiggle your fingers, or for lots of sparkles, find a fish net and wave that around in the water.  You’ll get to see the flashes of dinoflagellates in the bucket.  One night last summer, I went out on a boat at night with a fellow student to help with his project.  The wake of our motor boat glowed pale blue behind us and the rope of the anchor sparkled as the boat shifted with the currents.  It was magical, seeing the stars sparkling above us and the dinoflagellates below!

Bioluminescent footsteps

As magical as glowing footprints in the sand! Credit: Flickr

We aren’t the only ones who disturb the water and make it glow.  Sea life in the water also make the water light up, to either their benefit or detriment.  Check out the video below to see some of the ways animals cause dinoflagellates to sparkle in their own ways.

One of the most memorable bioluminescence moments for me was last year when I was out on a research cruise off the central coast of California.  The officers on the bridge let us know there were dolphins riding the bow wave of the ship one night.  We went to the bow and could hear the dolphins, but couldn’t see anything.  Then, as our eyes adjusted to the moonless night, first the stars became visible, then green trails started appearing in the water.  The trails split and coalesced and criss-crossed in front of the ship–they were caused by the dolphins as they surfed the bow wave!  Humboldt squid flashed with their own bioluminescence as the dolphins chased them in the water.  As our eyes adjusted further, ever more dolphin trails and squid flashes became visible and the Milky Way grew visible overhead.

Share your bioluminescence stories below, and if you haven’t sought it out yet at night, get out to the water and check it out!

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