The famed bioluminescent bay in Fajardo, Puerto Rico, known as Laguna Grande, has stopped glowing and officials are worried.
The lagoon, which has charmed visitors with its neon blue radiance, may be suffering due to construction runoff, inclement weather or people clearing mangroves to allow larger boats into the area, the Associated Press reports.
Scientists headed to the area Tuesday to help diagnose the problem.
"We have been compiling data," Carmen Guerrero, secretary of the Department of Natural Resources, said in a phone interview as she headed toward Las Cabezas de San Juan Nature Reserve with a team of scientists to investigate the problem. "There are a lot of factors that could be at play."
The bioluminescence has dropped so much that tour operators have had to cancel trips and reimburse visitors, Guerrero said.
"We've never seen anything like that," Fajardo mayor Anibal Melendez said of the bay being dark for eight days.
The construction of a water and sewer plant has garnered the most attention.
Alberto Lazaro, president of the state Water and Sewer Authority, said the plant is needed because people are discharging sewage into the lagoon and nearby ocean. He said the project, which is to be completed by 2016, had been approved by the territory's Department of Natural Resources and the U.S. Environmental Protection Agency, which is providing the funding.
There are 11 companies currently offering boat and kayak tours of the lagoon, and up to 700 jobs in Fajardo benefit from bio bay tourism, Fusion reports.
The unique glow is created by its large population of dinoflagellates, a special type of plankton that inhabits its waters. Puerto Rico has two other bioluminescent bays.
Adrian Carrasquillo is the White House correspondent for BuzzFeed News and is based in Washington, DC.