Scientists launch probe into sudden loss of bioluminescence in Vieques’ Mosquito Bay
By THE STAR STAFF
Scientists have launched a field investigation into the unexplained disappearance of bioluminescence in Mosquito Bay, Vieques, after the lagoon began showing signs of ecological change earlier this year, raising concerns about the health of one of Puerto Rico’s most renowned natural attractions.
The Puerto Rico Science, Technology and Research Trust provided the information.
Researchers say that in September 2026, the lagoon experienced a sharp decline in populations of Pyrodinium bahamense, a species of dinoflagellate responsible for the bay’s characteristic glow. The decline was followed by what scientists have described as a bioluminescence “blackout,” prompting efforts to determine what may have disrupted the ecosystem.
The investigation was sparked after David Gondek of Ithaca College contacted microbiologist Natasha de León Rodríguez, director of the Research Grants Program at the Puerto Rico Science, Technology and Research Trust, to explore whether microbial communities within the lagoon, particularly bacteria, may also have been affected.
To begin answering those questions, a team from the Inter American University of Puerto Rico’s Metropolitan Campus (Inter Metro), working in collaboration with the Vieques Conservation and Historical Trust, conducted field visits to collect environmental data and biological samples from the lagoon.
Researchers said the primary objective is to assess the health of the ecosystem and develop potential hypotheses to explain why the lagoon’s celebrated bioluminescence has disappeared.
During two field expeditions coordinated with the Vieques Conservation and Historical Trust and local collaborator Mark Martin Bras, scientists gathered water samples and conducted measurements at multiple locations throughout the lagoon. The team evaluated key environmental indicators, including dissolved oxygen levels, temperature and salinity.
The collected samples are being distributed for a range of laboratory analyses, including phytoplankton and zooplankton counts as well as bacterial DNA sequencing. Scientists hope the findings will provide a clearer picture of the lagoon’s current ecological conditions and help determine whether the dinoflagellates associated with the bioluminescent phenomenon remain present.
Researchers emphasized that the study is intended to identify possible explanations rather than confirm any specific cause behind the loss of bioluminescence.
“The results will serve as a starting point for developing hypotheses,” the research team said, noting that no conclusions have yet been reached regarding what may have triggered the changes observed in the lagoon.
The project also includes participation from workforce fellows, graduates of Inter Metro currently involved in the National Science Foundation-funded Navigating Home program led by María Fernanda Barberena and de León Rodríguez.
The fellows bring practical experience in water-quality monitoring after spending a year working in Laguna Grande in Fajardo, another of Puerto Rico’s bioluminescent ecosystems. Their training allowed them to assist with sample collection and environmental assessments in Vieques.
Researchers said the students’ involvement highlights the role of field research in developing scientific talent while providing hands-on experience addressing real-world environmental challenges.
Puerto Rico is home to three year-round bioluminescent ecosystems located in Vieques, Fajardo and Lajas. Beyond their ecological significance, the bays are major tourism attractions that support local economies and businesses dependent on visitors drawn to the unique natural phenomenon.
Scientists say understanding how these ecosystems function and respond to environmental changes is critical for conservation efforts aimed at preserving both their environmental and economic value.
The Mosquito Bay investigation reflects the broader role of bioscience in natural resource management, demonstrating how the study of microorganisms and other ecosystem components can provide insights into environmental health and guide conservation strategies.
The next phase of the project will focus on analyzing the collected samples and sharing the results with the public. Based on those findings, researchers will determine whether additional studies are needed to further investigate the disappearance of the bay’s famous glow.
For now, the loss of bioluminescence in Mosquito Bay remains unexplained. But scientists hope that by examining the microscopic life forms that support the ecosystem, they can uncover the factors behind the blackout and help protect one of Puerto Rico’s most treasured natural resources.
