Sargassum in Tulum, what is it and where does it come from?

The term sargassum groups several species of brown algae within the genus Sargassum. It includes several species such as Sargassum vulgare, Sargassum filipendula or Sargassum cymosum. They are large in size and their structure is divided into the classic rhizoids, stipes and laminae, analogous to the roots, stems and leaves of vascular plants. Some species have gas-containing vesicles that enhance their buoyancy.

Sargassum algae are distributed throughout tropical and temperate zones and contribute significantly to the biomass of many coastal areas, providing food, substrate and protection for other marine plant and animal species. For example, loggerhead turtles (Caretta caretta) use it as protection for their eggs until hatching, and several species of crustaceans and fish have adapted specifically to take advantage of the resources it provides. In particular, it plays an important role in the migration of some eels, such as the European eel (Anguilla anguilla) or the American eel (Anguilla rostrata), which travel specifically to the Sargasso Sea to lay their eggs.

Sargassum has a great capacity for growth and reproduction (it can double its biomass in less than three weeks), due, among other factors, to its ability to reproduce vegetatively, that is, without the need for organs with a specific reproductive function.

Where the sargassum comes from

Most of the sargassum that reaches Caribbean beaches comes from the so-called Sargasso Sea. It is located in the Atlantic Ocean, near the coast of Brazil. The extension of the Sargasso Sea is variable, since it is defined by the amount of seaweed present at the time and by the marine currents. It is delimited by the Gulf Stream, the North Atlantic Current, the Canary Current and the North Atlantic Equatorial Current.

As a curiosity, it is worth mentioning that society has always had a difficult relationship with the Sargasso Sea. It has been named in different nautical texts since the 15th century, due to the fact that it was an area of difficult navigation. The large accumulation of seaweed, the virtual absence of winds and the confluent sea currents made it easy for sailboats to get stranded in its waters, with little chance of getting out.

Today, the dying sargassum loses its anchoring capacity to the substrate and other plants, and is dragged by the marine currents to the waters of the Caribbean Sea, among others. When it arrives, the decomposition process, in which substances such as sulfates are released, causes its characteristic foul odor.

The phenomenon does not show a defined chronology; it can occur at any time. However, there has been an upward trend in duration, intensity and frequency since 2013.

Areas most affected by sargassum and how it affects them.

These have been some of the most affected areas:

• Sargasso in the Riviera Maya: this area has suffered intense modifications due to sargassum, such as the installation of floating containment barriers and monitoring stations.
• Sargasso in Cancun: hotel and catering personnel in these regions have warned of up to 60% economic losses due to this phenomenon.
• Sargasso in Playa del Carmen: in Playa del Carmen there are already hotels that have adapted to this recurrent invasion, building pools that stop the entrance of the detritus.
• Sargassum in Tulum: in this beach the sargassum stain has reached up to 400 m2.

These examples are not exclusive to these beaches, but can be extrapolated to other affected coastal areas.

What sargassum is good for and how to take advantage of it

We can transform a threat into an opportunity. In 2018, at the request of the Mexican government, a group of scientists from UNAM formed a permanent working group to try to provide solutions to this problem on the beaches of Quintana Roo. Efforts have been made in the collection of sargassum, for example with the installation of barriers, and in the monitoring of the phenomenon, both to give early warnings and to rule out possible problems in human health.

Finally, these and other scientists have proposed several opportunities for the utilization of Sargassum algae or sargassum:

• Generate biomass: biomass can be used as fuel or for biofuel generation, etc. Here you can learn about what biomass is and what it is used for.
• Use as fertilizer: sargassum has a high content of nitrogen and other important nutrients, which can be used to fertilize fields if done properly.
• Extraction of important materials for industry: Sargassum is especially rich in alginate, a polysaccharide that is often used as a thickener in food products and even cosmetics.

Thus, effectively managed, we can reduce the impact and even benefit from this environmental nuisance.