Oceana Scientists Find Invasive Species and Deadly Coral Disease at Mexico’s Bajos del Norte Reefs | Oceana

Oceana Scientists Find Invasive Species and Deadly Coral Disease at Mexico’s Bajos del Norte Reefs

Press Release Date: September 29, 2021

Location: Mexico City


Anna Baxter | email: abaxter@oceana.org
Anna Baxter

Last month, Oceana completed the initial voyage of Project Alacranes, the organization’s first ever expedition in Mexico to investigate and document the health of the Bajos del Norte reefs. The team of 10 scientists found that while the reefs remain mostly healthy, they face previously undocumented threats including the presence of invasive lionfish and deadly disease in corals.

“We identified extraordinary seascapes, full of life, confirming the great value of this area. The presence of juvenile fish indicates that this reef is a vital place for the development of the species, that is, they need the conditions of this site to grow and migrate, or grow and fulfill their life cycle feeding other species,” said Mariana Reyna, Oceana’s Project Alacranes expedition leader.

Throughout the expedition, Oceana’s team explored seven sites, covering an area of 700 m2 (over 7,500 ft2), and captured 29,352 photographs, which will be used to create 3D maps of the documented corals. This is the first time this specific methodology will be used in México. The images will help the team accurately replicate the reef bottoms to continue their analyses out of the water.

Ten scientists specializing in different disciplines used cutting edge technology to monitor corals, mollusks, crustaceans, echinoderms, other invertebrates, and fish. Because very little scientific research has been conducted in Bajos del Norte, the findings of this expedition are crucial in determining the area’s biological wealth.

According to the results of this first stage of the expedition, specimens of brain (Pseudodiploria) and flower corals (Eusmilia fastiagata) from all sampling sites were found dead or with very advanced lesions. Several colonies of the corals of the Montastrea cavernosa species also showed lesions and mortality. In addition, some coral colonies have diseases such as yellow bands, black spots, and different levels of bleaching. This phenomenon was not observed on a previous visit to Bajos del Norte by a different group in 2019. Scientists say the extent and speed of the corals’ deterioration during that time is alarming.

“The cause of these corals’ deterioration may be stony coral tissue loss disease, which has not been previously reported in these reefs. However, the origin and impact of these diseases will be determined in the following months,” said Mariana Reyna.

Reyna added that the team recorded temperatures between 29 and 30°C (84 and 86°F) in the water. A temporal analysis is required to know how anomalous these temperatures are, and if this could be affecting biodiversity.

The expedition team recorded the presence of lionfish at almost every reef site visited. Lionfish are an invasive species that feeds on small species. Because lionfish have few native natural predators, their presence in these reefs threatens other fish populations and the overall balance of the ecosystem.  

“Environmental DNA samples were also taken at eight different sites. We are going to process this information to obtain lists of bony fish and invertebrates present at each site, and to learn if this is their habitat or is only part of their migratory route,” Reyna said.

Despite these threats, the reef community is largely in good condition, and the expedition team found no evidence of overfishing. However, scientists warn that despite the reef’s distance from the coast, Bajos del Norte remains vulnerable without legal protection. As scarcity increases in already exploited fishing areas, fishers will be forced to venture further from shore where existing monitoring efforts are limited.

“We managed to do science that has never been done in this area. Bajos del Norte was little explored until we arrived,” said Miguel Rivas, director of habitat campaigns at Oceana. “Science allows us to identify where to focus our efforts to preserve this wealth. We should not wait until the damage is done and the area is too devastated to act. Our oceans need us to make the changes that are required to protect them today.”

Oceana’s Project Alacranes expedition was supported by Blancpain, which has a 70-year legacy of exploring and protecting the oceans that began with its Fifty Fathoms diving watch. In 2016, the brand supported an expedition to Revillagigedo Archipelago, which largely contributed to the establishment of North America’s largest marine protected area one year later.   

“We appreciate Blancpain’s invaluable support of this expedition. Thanks to their commitment and enthusiasm, we are able to obtain the information we need to fulfill our mission of continuing to protect the world’s oceans and ensure that fishing communities can continue to take advantage of their resources,” said Renata Terrazas, Oceana’s leader in Mexico.

Oceana is also thankful for the support and contributions of Sobrato Philanthropies, the Wyss Foundation, the Scripps Institute of Oceanography of the United States, UNAM, and Conanp whose technology contributions made the work of this expedition possible.

Oceana plans to continue this expedition to the Arrecife Alacranes National Park (Scorpion Reef) and will announce soon the details of this second stage. Findings from these expeditions help inform Oceana’s campaigns to protect vital marine habitats and preserve ocean abundance.

Expedition images are available for download here


Oceana is the largest international advocacy organization dedicated solely to ocean conservation. Oceana is rebuilding abundant and biodiverse oceans by winning science-based policies in countries that control one-third of the world’s wild fish catch. With more than 225 victories that stop overfishing, habitat destruction, pollution, and the killing of threatened species like turtles and sharks, Oceana’s campaigns are delivering results. A restored ocean means that 1 billion people can enjoy a healthy seafood meal, every day, forever. Together, we can save the oceans and help feed the world. Visit www.oceana.org to learn more.