SAN JUAN, Puerto Rico (AP) -- Authorities in Puerto Rico announced Wednesday they are investigating why a glowing bay that attracts thousands of tourists a year has grown dark in recent weeks.
The popular Mosquito Bay on the island of Vieques is considered one of Puerto Rico's top attractions, and government officials say they are worried about the bay's loss of bioluminescence.
Department of Natural Resources Secretary Carmen Guerrero said she is reaching out to local and international scientists to launch an investigation.
"Puerto Rico is one of the few places in the world that has bioluminescent bodies of water," she said.
The bay's waters glow thanks to microscopic plankton known as dinoflagellates that emit a blue-green light through a chemical reaction when disturbed. The bay went dark in early January because of rough seas, but Guerrero said it is unclear why the glow diminished again in recent weeks.
Cristina von Essen, with Vieques-based adventure company Black Beard Sports, said the bay went dark about three weeks ago and remained in that state for about two weeks.
"It caught everybody by surprise," she said. "Not just us, but all companies that run tours down here were struggling. Everybody was a little bit frustrated."
She estimated that the company has lost about 400 tourists in recent weeks as a result of the darkening bay.
The problem has angered many tourists who had already made reservations for Vieques specifically to see the bay, according to Cristobalina Velasquez, a tour guide with Abe's Snorkeling & Bio-Bay Tours.
The company has seen about a 40 percent loss in clients in recent weeks, she added.
"Some operators have completely stopped offering tours," Velasquez said.
Other companies have opted to take tourists to a bioluminescent lagoon on Puerto Rico's northeast coast, which also went dark late last year because of rough seas and possible runoff. The lagoon has since regained its brightness.
Government officials said they also plan to boost vigilance around Mosquito Bay to prevent unauthorized companies from organizing tours to the area without enforcing certain regulations, such as a ban on jumping into bioluminescent waters to avoid contaminating them.
The Department of Natural Resources announced in February that it was building a water quality monitoring station to better protect the bay. The station is expected to measure the water's salinity, oxygen and temperature, among other things.