Periphyton: Jewel of the Sea
By: Dr. Ruscena Wiederholt, Computational Ecologist
I remember my first experience with the stuff. A recent transplant to Miami, I was on an airboat tour in the Everglades led by my colleague, Dr. Stephen Davis. At one point, he excitedly jumped out of the boat and grabbed an unappealing brown, squishy mat: periphyton. This is the kind of organism only a mother could love. I consider wading birds and alligators to be the poster children of the Everglades, but I had misjudged periphyton for its (rather) uncharismatic cover. Turns out there’s a whole other side to this stuff, just underneath its sodden surface.
For one thing, periphyton is akin to a whole microscopic village. It’s made up of various organisms including algae, cyanobacteria, fungi, microbes, plant detritus (decaying matter), and microinvertebrates. The word periphyton means “around” and “plant,” referring to the fact that it often grows on submerged plants. The entire Everglades ecosystem rests on this soggy mat. Periphyton is like the aquatic version of corn, which we feed to livestock, and then eat ourselves. Likewise, periphyton’s plant components produce energy, which is eaten by a variety of animals like frogs, insects, fish, and snails. These smaller animals then become food for larger animals like wading birds. So in the end, periphyton transforms into something beautiful. Similar to high-fiber cereal, it’s full of good qualities for the Everglades. It adds oxygen to the water, contributes to soil formation, and provides habitat for other animals. Because it responds so quickly to changes in its environment, it is also used as an indicator of water quality. In fact, studies involving periphyton were used to help establish the water quality (phosphorus) limits for the Everglades.
If you’re still having trouble getting past its spongy appearance, I can assure you there is an inner beauty to periphyton. I learned this while interviewing Dr. Evelyn Gaiser. Dr. Gaiser is an aquatic ecologist, and the George M. Barley Jr. Endowed Chair in Everglades Research at Florida International University. She is an expert on little things in the water like algae and periphyton, and her work is cited profusely in Everglades research.
At some point in the interview, I questioned the appeal of this squishy, Everglades concoction. I know periphyton steadfastly upholds the whole ecosystem, but it wasn’t ever going to grace the cover of a glossy magazine, right? To my surprise, she told me it was quite beautiful if you could only see it. To prove her point, she showed me a drawing of intricate shapes arranged in a pattern. Descriptions of these shapes wax poetic, jewels of the sea, living opals, algae in houses of glass. These are names for diatoms, a type of microscopic algae found in fresh and saltwater. They are encased in decorative walls of transparent silica, and resemble sets of tiny Christmas tree ornaments, complete with elaborate and festive patterns. And yes, these stylish, inspirational organisms are found in periphyton too!
As it turns out, diatom art is a thing. The Victorians started it back in the 1800s, arranging diatoms on glass slides for wealthy people’s amusement at parties. The list of quirky Victorian habits included fern collecting, making jewelry from human hair, and seances, so in comparison, microscopic artwork may not be so bizarre. The Victorian practice of seaweed scrapbooking may have died out, but diatom art is still going strong. Today however, artists are making diatom art on a scale you can see with the naked eye. For example, Xavier Cortada has worked with Dr. Gaiser to create paintings, digital art, drawings, and even fountains of diatom art. Diatom-inspired artwork has been on tours all over North America, and it adorns all sorts of unusual places from airports, turnpike plazas to city halls.
Don’t let their beauty beguile you, they’re extremely useful. With over 200,000 species, diatoms produce about 20% of the world’s oxygen and are an important component of marine food webs. Diatomaceous earth, as the name suggests, is made of diatoms, which pops up in all sorts of products like insecticides, cat litter, and even beer.
So next time your guide dives in for some floating brown mats in the Everglades—just remember, all that sogginess holds an assortment of extremely useful species. And if you’re lucky enough to see it, the hidden, single-celled gem of the Everglades.