Seaweed: Call It Not a Weed, But a Flower of the Sea

Seaweed on the beach. (Visit Florida Collection)

By Lauri deGaris

There are many types of seaweed, and their color and grace are emphasized by the sun in the underwater world. Seaweed has been dancing in the oceans for millions of years. Interestingly, it has played varying roles and asserted influence on society throughout history.

Science shows us many fundamental uses and applications for seaweed. A myriad of mythological tales and legends are shared by poets, artists, storytellers, and musicians about seaweed found in Neptune’s Garden. And, seaweed is a nutritious food, in high demand, worldwide.

The indigenous Seri along the Gulf of California in Sonora, Mexico harvest seaweed for sustenance. They have harvested eelgrass for centuries. The seaweed is dried and ground into flour used to make hot gruel, which was eaten with honey or sea turtle oil.

Nogging is the practice of packing seaweed between open spaces of wooden studs in barns, sheds, and houses along the seashore in the 1600s. Loose seaweed mixed with straw, mud, sand or clay has been used as a building material for at least the past 400 hundred years throughout North America and Europe.

In the mid-1700s seaweed was considered a very useful herb. Inhabitants along the coast found certain seaweeds to be sweet and salty and fed them to cattle. Seaweed also acted as bedding, mulch and an excellent fertilizer for crops.

 The Gentleman’s Magazine – July 1752 published by The Gloucester Journal, England reported:

“Sea-weed used to make soap in England, brown in color is similar to seaweed found in Spain. However, the seaweed in Spain was blue in color and produced a higher quality soap.”

Shirley Hibberd’s “The Sea Weed Collector.” (London: Groombridge & Sons, 1872.)

A popular passion among many in high society during the 19th century was to artfully collect and display seaweed. Increasing numbers of people traveled to the coast for pleasure. Guidebooks describe spending days of leisure visiting romantic shorelines strewn with flowers from the sea. Many seaweed collectors were women who arranged seaweed in “marine bouquets.” Seaweed was arranged for aesthetic effect and pressed for a day or two, allowing its natural adhesive to glue the specimen to paper.

Generations of artists depict seaweed images on decorative materials like silver, glass, cotton and bone. Countless oil, watercolor and acrylic paintings illustrate seaweed floating on canvas. Seaweed adapts fluidly to many mediums.

Plants evolved from ancient seaweeds. It is where they get their green chlorophyll. Inside seaweed cells, chloroplasts contain pigments that range in color from green, red, blue, brown, pink, purple, and on and on. These pigments collect different wavelengths of light filtering through the water. Of course, the light helps them photosynthesize for efficient growth. Most important of all, seaweed produces a tremendous amount of oxygen for our use.

Sargassum, a type of seaweed, begins life in the open Atlantic Ocean. It prefers areas where prevailing currents collide, forming landless boundaries. Like all other ecosystems on Earth, it is constantly changing in size and shape. The Great Atlantic Sargassum Belt is a biomass of seaweed stretching from Africa to the Gulf of Mexico.

Sargassum is a seaweed that contains gas-filled structures, called pneumatocysts, filled with oxygen. This enables large rafts of sargassum to float on the water’s surface. Floating seaweed provides food, refuge and breeding ground for numerous plants and animals.

Sargassum. (NOAA)

Sargassum seaweed comes ashore along the Southeast U.S. in large quantities. Sea turtles, crabs, shrimp, fishes and numerous other aquatic creatures living near the surface depend on this seaweed soup for existence. Sargassum is also important when it is washed ashore. It fertilizes dune plants and harbors food vital for resident and migratory shorebirds.

Seaweed can be considered a nuisance. Once on land, it will begin to decompose releasing hydrogen sulfide gas which smells like rotten eggs. This past spring, a seaweed invasion was predicted for the Florida coast. And, indeed many coastal communities were blanketed with sargassum seaweed.  However, since that time, temperatures and currents have changed and the size of the large spring bloom has decreased by 40% according to NOAA.

Locally, sargassum seaweed ends up on the beach after a tropical storm or a powerful nor-easter. When this occurs, baby sea turtles floating in the mass of sargassum grass, are deposited on the beach in the wrack line. The wrack line is the place along the shore that marks the high tide and is where ocean debris regularly collects. Should you discover a baby sea turtle in the wrack line along the shores of Amelia Island please call Amelia Island Sea Turtle Watch, Inc. at 904-583-1913 for assistance.

The medical industry has discovered highly effective uses for seaweed. Medical cloth for wound dressings and packings can be made from various types of seaweed. When mixed with sodium, a gel is produced by the seaweed. This overlaid on a wound creates a micro-environment that induces healing.  Also, certain types of kelp contain high levels of iodine, which is used by the medical industry.

Seaweed is a healthy snack and is often called a superfood. It is packed with minerals and antioxidants as well as vitamins A, C, E, and B12. Certain species of kelp are popular like Wakame or sea-mustard and are found in Miso soup. In East Asia, Kombu, a type of kelp, is also very popular. Nori is roasted and pressed into dried sheets similar to paper and used to wrap sushi rolls. Dulse, which has been harvested for thousands of years, has a soft leathery texture and tastes like bacon. Irish moss is a purple and red seaweed used in desserts like ice cream because of its carrageen content. Carrageen is a sugar molecule and is used as a thickening agent in many food products. And sea lettuce, also known as Ulva, can be found locally in the winter months. Ulva collected and dried in the sun has a refreshing, salty taste in addition to many nutritional benefits.

It is my hope that the next time local beaches are blanketed with sargassum seaweed, we do not malign this important plant as a nuisance. But instead, we respect and value these flowers of the sea.

Call us not weeds – we are flow’rs of the sea-

For lovely and bright and gay-tinted are we;

Our blush is as deep as the rose of thy bowers.

Then call us not weeds – we are ocean’s gay flowers.

           E.L. Aveline – 1840.

2 Comments
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Mark Tomes
Active Member
Mark Tomes(@mtomes)
7 months ago

Thank you for this wonderful treatise on sea plants!

Richard Timm
Trusted Member
Richard Timm(@rtimm-ontheislandgmail-com)
7 months ago

Dulse is still very popular up here (Canada), plus rockweed is harvested as fertilizer.