Waving Hello

What Can Make Breaking Waves Turn Blue?

This week, we’re returning to the surface and looking at one of the greatest bioluminescent spectacles that can be observed. It can occur along coastlines and in harbors worldwide and comes from the smallest organism detailed so far in Season 8. This glow comes from the cumulative emanation of many single-celled organisms called dinoflagellates (note that despite the same spelling, its root word origin is not the same as ‘dinosaur’; while both Greek, the former comes from the word ‘dinos’ for ‘whirling’ and the latter from ‘deinos’ for ‘terrible, potent, or fearfully great’).

Dinoflagellates are an extremely diverse group of over 2,000 species. The majority are free-swimming marine organisms, though they can also be found in freshwater environments and in symbiotic relationships with larger organisms (including both mutualistic and parasitic relationships). In Florida, ‘red tide’ is frequently caused by the dinoflagellate Karenia brevis. There are over 18 genera of dinoflagellates that possess bioluminescence. One of the more common species is Noctiluca scintillans, also known as the sea sparkle or sea ghost.

Bioluminescent dinoflagellates all possess the same kind of luciferase enzyme that catalyzes the reaction. If you recall from the introduction to this season, evidence suggests these proteins developed independently multiple times in different taxonomic groups. In addition, because of their single-celled nature, the activation of their bioluminescence is entirely based on a stimulus response. For most dinoflagellates, the stimulus is physical disturbance. This is why it can often be seen in breaking waves like the above photo. However, any kind of movement will do, including swimming people and boat wakes.

This phenomenon is quite widespread. The cover photo was taken in San Diego, California. The first of the last three in sequence is a long exposure image taken in Zeebrugge, Belgium. The second is from New Jersey and the third from Jervis Bay in New South Wales Australia. It does require a large enough concentration of the bioluminescent organisms, which means conditions are better for it in some places because of increased food availability or proper environmental conditions for the chemical reactions (for example, in dinoflagellates, the reaction is pH dependent). It can also occur over large swaths of the open ocean surface, called ‘mareel’ or the ‘milky seas effect’.

As for what purpose the bioluminescence serves for these organisms, that is difficult to determine. Alone, the flash of light only lasts one tenth of a second each time. This makes it relatively weak for solitary use, but in large numbers it can be used for similar purposes as the Latia snails mentioned earlier this season: to confuse predators or attract something larger to prey on those predators instead. Remember, an organism need not have to consciously activate such safeguards in order for them to develop or be effective. If the stimulus response of motion leading to the bioluminescent reaction did reduce predation, it would be passed on to future generations.

Unfortunately, even beauty does not always come without cost. While a species like Noctiluca scintillans is not particularly toxic compared to others (it does not secrete potent neurotoxins like some species do), it can still create a hazardous environment for other marine life if encountered in sufficient quantities. Like all living things, it must excrete waste products left over from its metabolic processes. While many dinoflagellates are photosynthetic, it is not and its consumption of phytoplankton can produce high levels of ammonia, a waste product that is highly toxic, especially in aquatic environments.

I hope this week’s story reminds you that even very small organisms can create things of great wonder working in concert. While the large and impressive creatures always manage to hold our interest, don’t be afraid to look for the beauty of nature in more unexpected places. As always, please like and share if you enjoy my writing and as we move closer to the end of Season 8, let me know if you have any ideas for future Nature Stories topics. If I use your idea, I’ll give you a mention in the introductory post.