According to the monitoring data, 10 beaches in Cancun are in green color, that is, they have very little seaweed, this does not mean that there is none, but that it is good for swimming; one is in yellow, none is in orange color, with abundant seaweed and none is with excess, in red color. The affected parts or beaches in Quintana Roo are Playa Delfines, Punta Nizuc, Playa Coral, Riviera Cancun, Moon Palace, Royalton Riviera, Bahia Petempich, Puerto Morelos Centro.

According to the Citizen Observatory of Sargasso and the Sargasso Monitoring Network of Quintana Roo, no beach is found with an excess seaweed, also no beach has the abundant presence of this seaweed, 8 are in yellow (moderate), 52 are in green (very low) and 20 are without seaweed.

The information also indicates that some of the spots that are free of seaweed and can be enjoyed in peace, without any discomfort, are Holbox, Isla Contoy, Isla Mujeres, Costa, and Playa Mujeres, some spots in the Hotel Zone of Cancun, West Cozumel, and Bacalar Lagoon.

It should be noted that out of the 11 municipalities, Cozumel continues to be the one with the least presence of seaweed, with at least 12 blue and 8 green spots, as stated by the citizens themselves on social networks and also confirmed by the Sargasso Monitoring Network of Quintana Roo.

The seaweed status indicator of the certified beaches in Cancun.
The seaweed status indicator of the certified beaches in Cancun today. Red - excessive, Orange - abundant, Yellow - moderate, Green - very low levels of sargassum. Image: Zofemat

Business sector

Cancun hoteliers invest around half a million dollars in the containment and cleaning of the beaches due to the arrival of the seaweed during the eight months that the incidence of seaweed lasts in the areas. This cost for the hotels is represented in the barriers anchored to the sea, the daily maintenance, the displacement of machinery, the hiring of workers to collect the seaweed on the beaches daily, both in Cancun and the Riviera Maya.

The massive seaweed infestation has not caused cancellations or early departures of tourists, so hotel occupancy in the main destinations of the Mexican Caribbean remains stable. Hundreds of tourists continue arriving at the Cancun beaches despite the massive seaweed invasion registered on the coasts of Quintana Roo, which is already worrying the hotel and services sector, as it is feared that it may impact the mood of both national and foreign visitors.

Around three-quarters of Quintana Roo's economy depends on tourism, the sector most affected by mobility restrictions to control COVID-19, some of which are still in force and, in the particular case of the state, are at "imminent risk" of increasing if it returns to red on the epidemiological indicator. Banorte analysts estimate that Quintana Roo's Gross Domestic Product (GDP) suffered a historic 24.2% plunge in 2020, the most severe in the country, and it will take until 2027 or longer to fully recover the levels of economic activity it had in 2018.

How Mexicans combat seaweed in Cancun

In the case of seaweed containment in shallow waters is the responsibility of the Secretary of the Navy, which is carried out with sargassum seaweed boats, while the terrestrial response in public beaches is the responsibility of the local authority, through the Federal Maritime Terrestrial Zone (Zofemat) and Municipal Public Services.

Specialized machinery such as seven sweepers coupled to agricultural tractors and special units for the removal of the seaweed and its transfer to the final destination. Seven manual sieving machines allow the removal of solid waste such as bottle caps, cigarette butts, microplastics, glass, among others, which come ashore along with the seaweed. Sargassum collection points have been set aside in the sandy beaches of Playa del Niño, Playa Las Perlas, Playa Delfines, and Playa Coral, for drying and screening, for subsequent transfer to the final site.

Monitoring and detection of seaweed in Cancun

The Ministry of the Navy informed that since March it started monitoring sargassum in the Caribbean Sea, to contain the seaweed. The Direction of Meteorology of this Institution and the Oceanographic Institute of the Gulf and the Caribbean Sea monitor this phenomenon, and have determined the elaboration of meteorological forecasts of the conditions that occur in the Caribbean and of the seaweed patches in the high seas.

Reconnaissance flights are carried out by Mexican Navy aircraft to check for any patches of seaweed that may reach the Mexican coasts. Coastal vessels are carrying out surveillance actions, while sargassum boats are carrying out the collection, and tractors and land sweepers are ready on land.

Sargassum is brown algae, whose biomass has grown and its origin is probably linked to climate change and other global anthropogenic environmental alterations. The large seaweed belt originates off the coast of West Africa and is moved by ocean currents towards the Americas. These macroalgae find conditions to grow due to the precipitation of dust from the Sahara desert and the nutrients they find on their way to the Caribbean.

The amount of seaweed that in other years has reached the coasts has severe impacts on ecosystems and species of high biological value; alterations have been observed in the Mesoamerican Reef System, where both the reef and the seaweed are affected because the layer of sargassum on the water impedes the passage of light.

What is sargassum and where it comes from?

Sargassum is a large macroalga, meadow, or dark green color, which grows in the seas and moves by the currents of the oceans. If the conditions for its growth are optimal, in less than twenty days it doubles its biomass (as it is happening), since it has the facility to grow very fast. In this way, the algae turn brown on the paradisiacal beaches of the Mexican Caribbean and pose a real threat to the tourist interests of the region.

The seaweed reaches the Caribbean from two main sources: the Sargasso Sea, in the Bermuda Triangle, and a new area, north of the equator, where it accumulates off the coast of Brazil to enter the Caribbean. Sargassum on beaches is an indicator of pollution and increased damage caused by human activity in the seas and Caribbean coasts, where there are irregular settlements and inadequate treatment of sewage and greywater.

The seaweed arrival is a regional phenomenon that affects, without distinction, all the coasts of more than 30 countries, territories, and different protectorates. Sargassum is reported from the coasts of Cuba, Turks and Caicos Islands, Inagua, The Bahamas, Jamaica, Grand Cayman, Haiti, the Dominican Republic, Puerto Rico, Honduras, and also the coastal region of Quintana Roo Mexico.

Also, further east, all the islands of the Lesser Antilles arc are affected, such as the British Virgin Islands, Saint John, Saint Thomas, Culebra, Antigua, and Barbuda, Montserrat, Guadeloupe, Martinique, Dominica, Saint Lucia, Barbados, Saint Vincent, and the Grenadines. It also arrives in Granada, Trinidad, and Tobago, Curacao, Margarita Island, Aruba, the Atlantic Coast of Brazil, French Guiana, Suriname, Guyana, Venezuela, Colombia, Panama, Costa Rica, Nicaragua, Honduras, Guatemala, Belize, and the Peninsula of Florida in the United States.

Sustainable solutions to the seaweed problem

Sargassum can be used as fuel, energy generator, fertilizer, animal feed, and has become useful raw material in several industries which could leave great contributions to Mexico. From the problem that brought the arrival of seaweed to the Mexican Caribbean coast, researchers, universities, biologists, and ecologists from Mexico, Japan, and other parts of the world, studied the composition and properties of these macroalgae. It has many positive, sustainable applications and whose impact will be long-term.

Sargassum has recently been used in the preparation of blocks or bricks to be used in construction. This application is ecologically more friendly and economically more profitable. There are already buildings made with sargassum bricks, which means that it is a viable and safe building material. For the construction of approximately 40 square meters, 20 tons of seaweed would be used and create 2,150 blocks of this seaweed, which represents a relief because it will not be treated as waste.

In addition to being a sustainable material, the use and exploitation of seaweed would have a positive impact on costs, since construction investment would be reduced by up to 50 percent and would be a replicable construction model in states such as Durango, State of Mexico, Zacatecas, among others. The Ministry of Ecology and Environment of Quintana Roo conducted studies on the blocks created with sargassum and defined that their resistance is between 75 and 120 kilos, while the durability can be up to 120 years regardless of the region or type of climate where they are used.

Currently, there are no sustainable materials so resistant even with that period of life. This means that the buildings made from this seaweed will be sustainable and ecological. On the beaches of Quintana Roo, such as Tulum, Cozumel, Playa del Carmen, Akumal, Puerto Morelos, Mahahual, to name a few, construction of homes and hotels from the seaweed has begun, a trend that is expected to rise.

Sources: SEMAR, ZOFEMAT, La Verdad Noticias