My classified ad: "For $100 I'll bring liquor and fight you at the beach."
My first client was a little skinny guy. We downed the bottle like rockstars and went bare knuckles.
I regained consciousness the next morning face-down in a blob of sea foam. I pondered the sea foam while I looked for a missing tooth. The fog rolled in and the diffuse light produced psychedelic colors in the bubbles.
I told my next drunken fight partner how beautiful sea foam is. I told him that the swirling colors were due to a phenomenon called "thin film interference." He insisted that sea foam is caused by industrial pollution and that people should never touch it. Recalling that sometimes I'm the idiot, I didn't argue.
The incoming tide woke me. And while cleaning sand from my black eyes, I reviewed what I knew about natural sea foam.
Sea foam was mentioned in stories and poetry long before the Industrial Revolution. Shakespeare mentions the "foaming brine" in The Tempest. And there's this popular 14th century nursery rhyme:
Sea foam, oh, sea foam! Where is thine home?
Little lass, oh, little lass! On the sea surface, you dumbass.
So, surely sea foam has natural origins and isn't due solely to industrial chemicals.
Natural sea foam is caused by a mix of proteins and other materials of organic origin produced during the decomposition of organisms, especially algae. The thin, ever-present slick of this "sea surface microlayer" has soap-like surfactant properties, so it forms persistent bubbles when agitated by surf. Other known ingredients include fats, sugars, bacteria, pollen, wood polymers, fungi and the residue of pretty much anything that breaks down in the ocean.
These molecules form a nutrient-rich foamy stew that lots of microorganisms, and even some bigger animals such as small crustaceans, use as a food source and physical habitat. Because blobs of sea foam can be blown inland, they distribute marine-derived nutrients some distance from the sea. In fact, fungal and algal spores get concentrated in sea foam and can be distributed to new habitats this way. Plus, I enjoy watching balls of blowing sea foam roll across the beach getting smaller and smaller like anti-snowballs.
According to the internet, natural sea foam isn't necessarily toxic. But when toxic organisms break down, their toxins can become concentrated in sea foam. Examples of these organisms that may occur locally include certain single-celled algae and dinoflagellates, which can bloom into so-called red tides.
Sea foam near urban areas or petroleum plants, for example, may concentrate unnatural pollutants. Just about anything that might be in the sea surface microlayer can end up in sea foam. And some sea foam in polluted locations may be largely made up of contaminants. It's very complex stuff.
In the late 1980s, I worked on a project sampling offshore pulp mill effluent by dipping a pane of glass into the water so the surface microfilm would stick to it. My boss expected effluent chemicals to be in the film, so these chemicals would have been in sea foam, too. And surfers near the Samoa Peninsula effluent outfalls experienced skin and eye irritation, as well as other illnesses.
Anyway, my next client was a small girl. I said, "Little lass, you are too young for drinking and fighting. Can I tell you about sea foam instead?" I awoke the next morning covered in sea foam with a broken nose.
So, I wouldn't know if any given sea foam is hazardous. But at least during water quality alerts or algal bloom warnings, it's probably best to avoid it. Also avoid drinking and fighting.
Biologist Mike Kelly (he/him) is also the author of the book Tigerfish: Traditional and Sport Fishing on the Niger River, Mali, West Africa. It's available at Amazon or everywhere e-books are sold.