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?
Sargasso (also called "Gulf weed" or "Deception weed") is known as a genus of around 150 species of brown, macroscopic and 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.
Sargassum is a blackish brown or green algae. Their bodies are made up of rhizoids (equivalent to the root of the plants), stems (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 the photosynthesis constant.
It is common to find sargassum attached to corals, reefs, or stones, making life like long spikes. It is also found floating adrift in patches that can extend even for kilometers, also promoting a ecosystem between its branches.
In the latter case, groups of this alga are usually found piled up on the shore of the river. sea, especially in the Caribbean coasts, in what is known as “brown tide”.
Sargassum can be a significant ecological threat, causing:
- Reduction of light and oxygen in the regions flooded by algae.
- Acidification of waters (by biological production of hydrogen sulfide).
- Increase in nitrogen and phosphorus concentrations.
- Replacement of other algae communities.
- Suffocation of certain animal species (such as turtles and fish) and overfeeding those that feed on sargassum.
- Damage to the tourist industry (bad odors when decomposing on the beach).
At the same time, sargassum could serve as an organic input for the production of biofuels, fertilizers, building materials and even paper.
Sargassum situation in the Mexican Caribbean
Since the summer of 2013, the coasts of the Mexican Caribbean have registered 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 the sightseeing, the main economic activity of a region considered paradisiacal.
Between 2014 and 2015 the situation became constant. The State of Quintana Roo was particularly affected: up to 500 thousand tons of the algae was collected in 2018. It is estimated that by 2019 it will be possible to double, almost one million tons of sargassum.
The reason for this sargassum invasion is estimated to be the use of fertilizers in the South American region. Those compounds Sulfates are swept out to sea by the rains and rivers, generating an abnormal proliferation of the algae. Other explanations point to global warming, which favors the rate reproductive of the alga.
In their efforts to combat the brown tide, the Mexican authorities have resorted to various mechanisms, including the release of microorganisms aquatic plants that could biologically combat sargassum. This has sparked controversy in the scientific community, since the long-term results that such practice can bring are ignored.