We explain what sargassum is, where it is found, its causes and why it is an ecological threat. Also, the situation in the Caribbean.
What is sargassum?
It is known as sargassum (also called “Gulf weed” or “Deception weed”) a genus of about 150 species of brown, macroscopic, planktonic algae.
These algae are found in the tropical regions of the globe, especially in the Atlantic Ocean, in whose northern region is the Sargasso Sea, the only sea whose name is due to physical and biological reasons without having the presence of coasts.
The sargassum It is a brown or blackish green algae. Their bodies are made up of rhizoids (equivalent to the roots of plants), stipes (equivalent to stems) and laminae (equivalent to leaves), which often have flotation bladders, in the form of small balls filled with gas, whose role is to keep the algae afloat to allow constant photosynthesis.
It is common to find sargassum attached to corals, reefs, or stones making life like long spikes. It is also found floating in spots that can extend for kilometers, also fostering an ecosystem among its branches.
In the latter case, groups of this algae are usually found piled up on the seashore, especially on the Caribbean coast, in what is known as the “brown tide.”
The sargassum can constitute an ecological threat important, because it causes:
- Reduction of light and oxygen in the regions flooded by the algae.
- Acidification of waters (due to biological production of hydrogen sulfide acids).
- Increase in nitrogen and phosphorus concentrations.
- Replacement of other algal communities.
- Suffocation of certain animal species (such as turtles and fish) and overfeeding of those that feed on sargassum.
- Damage to the tourist industry (bad smells when decomposing on the beach).
At the same time, sargassum could serve as an organic input for the production of biofuels fertilizers, construction materials and even paper.
See also: Aquatic ecosystem
Situation of sargassum in the Mexican Caribbean
Since the summer of 2013, the coasts of the Mexican Caribbean have recorded sporadic waves of sargassum which ended up rotting on the shore of the beach. This has occurred especially in the States of the Yucatan Peninsula, affecting tourism, the main economic activity of a region considered paradisiacal.
Between 2014 and 2015 the situation became constant. The State of Quintana Roo was especially affected: up to 500 thousand tons of the seaweed were collected in 2018. It is estimated that by 2019, double that amount could be reached, almost one million tons of sargassum.
It is estimated that the reason for this sargassum invasion is the use of fertilizers in the South American region. These sulfated compounds are swept into the sea by rains and rivers, generating an abnormal proliferation of the algae. Other explanations point to global warming, which favors the reproductive rate of the algae.
In their efforts to combat the brown tide, Mexican authorities have resorted to various mechanisms among them the release of aquatic microorganisms that could biologically combat sargassum. This has sparked controversy in the scientific community, since the results that this practice can bring in the long term are ignored.
Continue with: Marine currents
References
- “Sargassum” on Wikipedia.
- “What is sargassum and why is it produced?” on Mexico.com.
- “Sargasso” on NaturaLista.
- “Invasion in the Caribbean. Sargassum punishes the beaches of Mexico and Miami” in La Nación (Argentina).
- “Sargasso” in Treccani Encyclopedia online (Italian).
- “Sargassum” in The Encyclopaedia Britannica.
