TULUM, Quintana Roo – In recent decades, the planet has been grappling with the mounting stress of climate change, coastal pollution, and a devastating disease known as white syndrome. These factors have collectively wreaked havoc on the once-thriving coral reefs, causing significant destruction within a span of just a few decades.
According to Lorenzo Álvarez Filip, a researcher at the Academic Unit of Reef Systems in the Institute of Marine Sciences and Limnology at UNAM in Puerto Morelos, Quintana Roo, nearly 60% of the coral reefs in the Mexican Caribbean have been lost between 1980 and 2015. The surviving corals are those that exhibit tolerance to stress, withstanding rapid environmental changes. However, these corals are relatively small and lack the capacity to build extensive reef structures.
Despite occupying less than 0.1% of the world’s ocean surface, coral reefs serve as crucial habitats for 25% of known fish species, in addition to providing shelter for crustaceans, mollusks, and algae. They act as natural barriers against hurricanes, safeguarding not only the coastline but also the tourist infrastructure. Furthermore, they contribute significantly to fisheries production and serve as a major attraction for tourists in Quintana Roo, making the conservation of Mexico’s coral reefs of paramount importance.
While the Mexican Caribbean boasts some of the most stunning coral reefs in the country, other ecologically and touristically significant reefs can be found in Veracruz, Tuxpan, and along the entire Pacific coast, where these tropical ecosystems thrive.
Erosion poses a significant threat to the coral reefs. As coral skeletons naturally erode, parrotfish, sea urchins, and various types of sponges contribute to the production of sand.
According to Álvarez Filip, the pristine white sands on the coasts of Cancún, Playa del Carmen, and Tulum are the result of the perpetual battle between construction and erosion. When these processes are in balance, they ensure the existence of healthy coral reefs. However, the prevalence of erosion over construction has led to the flattening of reef structures, negatively impacting the ecosystem services they provide, such as coastal protection and biodiversity.
Coral reefs are colonial organisms composed of hundreds or thousands of small animals called polyps, which are closely related to anemones and jellyfish. Ranging in size from millimeters to centimeters, these polyps form colonies that host symbiotic dinoflagellates known as zooxanthellae. The combined efforts of polyps and zooxanthellae result in the formation of coral reefs, with both parties secreting calcium carbonate, the stony skeleton of reefs.
Álvarez Filip further explains that the slow-growing corals, particularly those belonging to the Orbicella genus, play a significant role in reef construction. Growing merely a centimeter per year, they take hundreds of years to reach heights of six to seven meters. Over geological timescales, these corals have formed the Yucatán Peninsula, a testament to their monumental contribution.
Since 2019, the loss of corals has been exacerbated by the emergence of white syndrome. Cozumel, for instance, was home to magnificent coral formations resembling Gothic cathedrals. In January of that year, a coral structure measuring five meters in height and seven meters in length, painstakingly built over four centuries, stood tall. Yet, merely four months later, it had succumbed entirely.
White syndrome is to corals what Covid-19 is to humans: a pandemic known as an epizootic when it affects animals. It is believed to be caused by waterborne bacteria that have devastated corals throughout the Mexican Caribbean. In less than a year, the syndrome has spread from northern regions, such as Cancún, to Xcalak on the border with Belize, rapidly encroaching upon the reefs.
To counteract the high mortality rate of corals, various efforts have been undertaken to restore the reefs. This involves breaking corals into small fragments or rescuing those displaced by hurricanes, which are then cultivated in aquariums or nurseries before being transplanted back into the seafloor.
Groups of scientists, particularly in Puerto Morelos, are tirelessly engaged in transplanting and restoring corals throughout the Mexican Caribbean. However, the long-term survival of these restoration efforts hinges on mitigating the environmental disturbances and marine pollution that continue to claim the lives of corals.