top of page
  • Writer's pictureKay

What's Sargassum?

Updated: Sep 7, 2021

Sargassum is a genus of brown macroalgae, and if you are planning on traveling to the Caribbean or maybe to Florida then you might have heard about that phenomenon. The genus Sargassum contains over 300 species of brown algae distributed throughout the temperate and tropical oceans of the world, where they generally inhabit shallow water and coral reefs. The genus is widely known for its planktonic (free-floating) species. Like I said you can find it from Florida all the way down to Brazil.

Playa del Carmen in March 2018

Some species of this genus of algae may grow to a length of several meters. They are generally brown or dark green in color and consist of a holdfast, a stipe, and a frond. Some species have berrylike gas-filled bladders that help the fronds float to promote photosynthesis. Many have a rough sticky texture that, along with a robust but flexible body, helps it withstand strong water currents.


Sargassum muticum commonly known as Japanese wireweed. According to Wikipedia Sargassum was named by the Portuguese sailors who found it in the Sargasso Sea after the wooly rock rose (Halimium lasianthum) that grew in their water wells at home and that was called sargaço in Portuguese (Portuguese pronunciation: [sɐɾˈɣasu]).

The Atlantic Ocean's Sargasso Sea was named after the algae, as it hosts a large amount of sargassum.

The Sargasso Sea in the North Atlantic is bounded by the Gulf Stream on the west, the North Atlantic Current on the north, the Canary Current on the east, and the North Equatorial Current on the south. The Sargasso Sea (/sɑːrˈɡæsoʊ/) is a region of the North Atlantic Ocean bounded by four currents forming an ocean gyre.

Unlike all other regions called seas, it has no land boundaries. It is distinguished from other parts of the Atlantic Ocean by its characteristic brown Sargassum seaweed and often calm blue water.

Picture: > click on picture to enlarge

The naming of the Sargasso Sea after the Sargassum seaweed traces back to the early 15th-century Portuguese explorations of the Azores Islands and of the large "volta do mar" (the North Atlantic gyre), around and west of the archipelago, where the seaweed was often present. Gulfweed was observed by Columbus. Although it was formerly thought to cover the entirety of the Sargasso Sea, making navigation impossible, it has since been found to occur only in drifts.


I arrived here in Mexico in 2012 and it caught my attention in 2014. Not only here, but also the Gulf of Mexico and Florida had been affected.

What might be the cause of so much seaweed in the Caribbean's?

There are different opinions on that topic and just to mention two:

  1. climate change while they actually talking about the the rise in temperature which causes wind directions to change and these winds are blowing the loose mats of seaweed to the coastlines

  2. another theory is nutrient rich waters producing more sargassum, due to fertilizers from agriculte getting into the ocean - they provide good nutrition for the seaweed

Weather, wind and the currents make it a day-to-day changing situation. One day we can have a lot of sargassum coming in and another day nothing at all. It is really like gambling if your booking or are planning to book a vacation to this area. You just can not predict if seaweed is will be part of your holiday pictures or not. Negative impact

The seaweed obviously has a a negative impact on the tourism, since tourists do not like it when there is that brownish and smelling algae on the beach instead of the white sand they have been shown in the travel agencies and pictures.

Besides that there are some serious negative effects on flora and fauna. The patches of seaweed, cast a shadow and therefore are causing a light and oxygen reduction, which has a negative impact on the corals and marine grass, the sea grass growing on the ground.

​ Picture:

When piling up on beaches it makes nesting difficult for turtles. As you might know this area here is nesting ground for 6 species of sea turtles. While the beaches are hard to reach because of the accumulation of seaweed, it also makes digging the nest a difficult task. Due to its weight, it might even compress and actually destroyed the nest of the turtles. It also keeps the baby turtles from hatching and actually reaching the oceans.

Hotels try to keep up digging holes to bury the seaweed and in some cases are even using heavy machinery, which is destroying the turtle nests as well.

Something positive

Sargassum makes a great mulch for your gardening. Well, try to look at the bright side. That's great if you have a garden right next to the beach. It is also rich in nutrition, bringing nutrients to the dunes helping plants grow near the beaches, preventing erosion. These are natural benefits of helping to recover and redevelop beaches.

It is as well a natural deterrent to bugs, attracts flies and other insects and is therefore providing a source of food for sea birds.

Fun fact: Sargassum is commonly known as Japanese wireweed. It is also cultivated and cleaned for use as an herbal remedy. Many Chinese herbalists prescribe powdered Sargassum (either the species S. pallidum, or more rarely, hijiki, S. fusiforme) in doses of 0.5 gram dissolved in warm water and drunk as a tea. It is called 海藻; (suggestions how to pronounce it?) hǎizǎo in traditional Chinese medicine, where it is used to resolve "heat phlegm".

I'm hoping you learned something about the sargassum seaweed today and when next time you are it the Caribbean you look at the sarcasm maybe bit different. There are also alternatives, like getting on a boat with a snorkel trip, or visit an island. We do have a couple of islands here at the Yucatan peninsula. You might consider visiting some cenotes or Isla Mujeres, where you would enjoy the site of the island which does not have any seaweed on its beaches.

If you have any questions or concerns, please do not hesitate to write in the comment section below or send us an e-mail to:

Watch our vlog about sargassum on Youtube

Subscribe and listen to #kayspodcast on:



168 views0 comments


bottom of page