From above, you can appreciate the scenic beauty of the Bacalar Lagoon, located in southeastern Mexico, in the state of Quintana Roo. It is known as the “lagoon of the seven colors” because of the different shades of blue that the water has, as a result of the different depths at which it is found, as well as for the presence of mangroves, stromatolites and jungle that help purify it. Bacalar is also home to a diversity of migratory and aquatic birds, and mammals such as the spider monkey, however, these species and the lagoon system have suffered the impact of mass tourism, agriculture, deforestation and urbanization.
In view of this, the civil society organization Agua Clara has dedicated its efforts to monitoring the water quality of the lagoon and communicating the results to the population of Bacalar through a traffic light that alerts monthly to which areas along the lagoon are suitable for recreational use and which are not.
These inputs have been part of the Bacalar Lagoon Report Card, the most comprehensive study published in 2021 that collects the results of 10 years of scientific research, which concludes that the health status of the Bacalar Lagoon is regular, “however, the water quality is not optimal anywhere,” he says.
The report points out that the most affected area is the center-west of the lagoon, as it has been “significantly impacted by unsustainable urban development” from tourism, urban expansion and waste discharges in the city of Bacalar. This has caused a high presence of Escherichia Coli bacteria (E. Coli) and loss of mangroves.
View of the stromatolite reefs and red and botoncillo mangroves that inhabit the southwest of the Bacalar Lagoon, where there are not as many tourist or urban developments yet. Photo: Yanine Quiroz
In addition to water monitoring, which is carried out hand in hand with citizens, the community of Bacalar has other collective efforts to limit the traffic of boats on Wednesdays, to reforest mangroves and to extend environmental education to people.
Women caregivers of water
A few blocks away on the Cancún-Chetumal highway, in the city of Bacalar, is the Agua Clara Ciudadanos por Bacalar office, which since 2019 has been monitoring water quality in the lagoon. At the entrance, I am greeted by Naomi Buj, an organizational technician, who leads me through her laboratory with tables full of pipettes and microbiological analysis equipment and explains to me in broad strokes how they use these materials to carry out the analyses.
Later in the office, I speak with Melina Maravilla, the organization's executive director. She says that before knowing which areas of the lagoon are most and least contaminated, it is important to know that water quality depends on the monitoring sites and the characteristics of the monitoring being carried out.
Melina and Naomi at the Agua Clara Ciudadanos laboratory in Bacalar, where they carry out the analysis of the water quality of the lagoon. Photo: Yanine Quiroz
For example, the organization, together with trained volunteers, collects 100 millimeters (ml) of water for each sampling site at a depth of 30 to 50 centimeters; and from those 100 ml they subtract 1 ml with a pipette and place it in a culture medium to detect the type of microorganism or substance present in the water: from the TRIX Trophic Index that measures nutrients (chlorophyll, oxygen, nitrogen and phosphorus), to the presence of E. coli bacteria, which in high concentrations cause stomach infections that could endanger life of children and older adults.
“The midwest of the lagoon, where the city of Bacalar is located, is the one with the most concern, since there is a high monthly concentration of E. coli and an average of TRIX,” shares Melina Maravilla. The biologist adds that the causes of this pollution are tourism development, urban growth and agriculture, but in the case of E. coli, wastewater discharges.
“All mammals have E. coli in their faeces: humans and wild animals. But we have to take care of the high concentrations of this bacteria, which are attributed to wastewater discharges and lack of drainage in urban areas close to the lagoon,” he says.
For lagoon water to be considered unsuitable for recreational use, a sample must have nearly 200 colonies of E. coli —a colony is a group of these closely interacting bacteria. The results of water quality monitoring are communicated to the population through the traffic light that is published on the organization's website. Thus, yellow means that the lagoon is not suitable for swimming, while blue indicates that the water quality is excellent, green is satisfactory and red is heavily polluted.
Bacalar, home to stromatolites, chivita snails and mangroves
The health of the Bacalar Lagoon not only depends on water quality, but also on the presence of stromatolite reefs —communities of microorganisms, formed by the precipitation of carbonated minerals—as well as on the vegetation and mangroves that surround the wetland and help filter water and store greenhouse gases, which cause climate change.
Chivita snail represented on the wall of one of the streets in the city of Bacalar. Its importance lies not only in being food for humans and other species such as the snail sparrowhawk, but also because it helps control plant growth within the lagoon. Photo: Yanine Quiroz
At the same time, the lagoon is home to species such as the chivita snail (Pomacea flagellata), a mollusc endemic to Bacalar that helps to maintain the colors of the lagoon by controlling the growth of various plants, but which in the last two decades its overexploitation as human food has led to a drastic decline in its population.
Aldair Tuut is a young resident of Bacalar who has seen these changes in the lagoon up close. “Not only do we occupy the lagoon but also the animals, the lizards and the fish. The chivita snail was widely consumed and was even food for other animals such as the snail sparrowhawk. 8 or 9 years ago there were quite a few chivita snails on the shore of the lagoon, but now it's practically very rare to see them,” he says.
Tuut says that previously it was possible to swim without any problem inside the lagoon, but that in the last 10 years the population can no longer enter the lagoon because they fear contracting E. coli and getting sick. “I've heard people say outright: Well, I heard on the radio that the lagoon has bacteria and is harmful to us, so we're not going anymore,” he shares.
The lagoon has its own water dynamics: to the south, the flow comes from groundwater that enters from Xul-Ha and travels through the Rapids Canal to the center, in the city of Bacalar; while in the north, the water comes from a surface flow derived from rains and also from the lagoons of Noh Bec, Chacchoben and San Felipe Bacalar. The water from both poles converges in the center of the lagoon and flows out through the Pirates Channel to Chetumal Bay.
“Microorganisms such as fungi, bacteria, microalgae, invertebrates and mangroves absorb the minerals that the coast carries to grow and feed, and at the same time prevent this organic matter from contaminating the lagoon,” explains Héctor Hernández, researcher in the Department of Systematics and Aquatic Ecology at El Colegio de la Frontera Sur in Chetumal. For the scientist, the conservation of the lagoon requires the construction of a development model that does not contaminate and destroy vegetation, as well as regulation of land use and expansion of environmental awareness.
Environmental education is also one of the solutions promoted by the water quality monitoring program, which despite receiving few financial resources, has been able to continue thanks to the volunteering that people from Bacalarense carry out at least 8 sampling points, such as spas and public accesses. There they help observe the lagoon, prepare analysis materials, and even interpret results.
“As long as people know how the lagoon is located and why what we do is important, we will have a better answer for the conservation not only of water but of the landscape,” concludes the director of Agua Clara Ciudadanos por Bacalar.
* This work was supported by the Marine Journalism Network (Repemar), promoted by Causa Natura with the help of the Earth Journalism Network of Internews.
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