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A lagoon suddenly took on a pinkish color

Samuel Biener Weather Spain 7 mins
laguna rosa mexico
At the beginning of the month, the lagoon of Salina de Escobilla turned pink. Credits: Government of Tonameca.

The residents of the community of Escobilla, in the Mexican state of Oaxaca, had a big surprise a few days ago. As local fishermen and tour guides cruised the coastal Salina Lagoon, they saw that she suddenly turned pink.

They quickly alerted the authorities, who ordered an investigation into the reason for the unusual and sudden coloring of the body of water. However, for a few years there were signs of change.

Something has started to change in the lagoon

The fish began to swim disoriented, so much so that you had to put your hands in the water to catch them and pull them out. Later, some began to wash up on shore, swollen and smelling of sulfur. Finally, a few days ago, the color of the water turned pink.

It was first thought that the high concentration of salt could be the cause of this drastic change in the Salina lagoon. Until a few years ago, salt was mined from the bottom, hence its name. Tourists were stunned and word quickly spread to come and see the strange phenomenon, while locals were very worried, because fishing and tourism are their means of subsistence.

Halophilic bacteria, responsible for the pink color.

After an exhaustive analysis of the 40 hectares of this wetland, the Semadeso (Secretary of Environment, Energy and Sustainable Development of the State of Oaxaca) concluded that this change in the lagoon is due to a decrease in the oxygenation of the waters. The coastal lagoon is no longer in contact with the sea, which has resulted in a decrease in oxygen and the proliferation of bacteria, whose residues turn the water pink.

Because of this same lack of oxygen, the fish that inhabit its waters are dying. According to Semadeso biologists, this is a clear process of eutrophication. This is the scientific term for the excessive accumulation of inorganic nutrients in water, which triggers the proliferation of duanaliella salina algae, which causes the pink color.

When the salinity of the lagoon increases, the microalgae activate a defense mechanism and begin to produce an orange pigment. Over time, the microalgae are replaced by halophilic bacteria which tolerate the high concentration of salt well and produce a red or pink pigment. Research is still ongoing to identify the specific bacteria that produced the metamorphosis of this lagoon.

Pink Lagoon
The increase in the number of tourists has made it necessary to install signs warning of the risks of swimming in the lagoon.

Prolonged droughts and attacks on the territory endanger the lagoon.

The scarcity of precipitation and the increase in temperature in recent years have repercussions on a lagoon which, a few decades ago, could reach a depth of 10 meters. Now the maximum is usually around 5 meters, and right now there is barely a meter and a meter deep.

The main risk for the Salina Lagoon is that it will eventually dry up completely and that this process will become more frequent in the years to come. If climate projections come true, these droughts will tend to last longer in this region. Opening the gorge to connect the sea to the Salina would forever change the conditions of the lagoon.

In addition, it is necessary to take into account the aggressions perpetrated on the territory. The coastal road that passes near the lagoon is being widened, which forms a barrier for the rivers that carry fresh water to the lagoons. In addition, the owners of the land bordering the watercourses extract stone materials for use in construction.

Will the pink color disappear?

Fishing is no longer allowed in the lagoon, but the pink color of the lagoon is now beginning to attract national and international tourists who want to admire the spectacle. They come to take photos and videos, and upload them to social media. To take advantage of this sudden interest, Escobilla began controlling access and asking for voluntary contributions from visitors.

This phenomenon seems to be temporary. Biologists say the pink color will likely fade when the rains begin.

Biologists believe the pink color will fade when the rains begin, although a few showers have already fallen in recent days and it is still present. Everything suggests that this will be a temporary situation, as this phenomenon has also occurred in other Mexican coastal lagoons.

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