This article by Lizette Alvarez appeared inThe New York Times.
Sitting on a small boat in Mosquito Bay, a tapestry of stars above him, Mark Martin, a field researcher, scooped water into a canister. He studied the liquid for some sign of why, suddenly and inexplicably, one of the world’s most famous bioluminescent bays had dimmed.
“It’s all good tonight,” Mr. Martin said, about the water’s clarity, pH level, temperature and salinity — several factors that scientists hope may solve the puzzle of what ails the bay.
For as long as people can remember, the bay on the southern end of this islet, 10 miles away from Puerto Rico’s main island, has astonished first-timers who thrill to see the water radiate like a glow stick at night. But in January, the shimmering microscopic plankton known as dinoflagellates called off their show altogether. In recent weeks, they have brightened somewhat again, sporadically and halfheartedly, raising hopes that the popular bay may be regenerating.
The abrupt blackout has alarmed government officials, scientists and Viequenses, the islanders who depend on tourism to fuel their lackluster economy; one tour operator has already shut down. The bay has gone dark before, but never for more than several days. For now, visits to the bay are limited to weekends until the bay heals itself.
Most worrisome is that the dimming of the bay is a whodunit — a mystery that has stoked animus between locals and the business owners, nearly all of whom are Americans, who run tourist trips to the bay. Because bioluminescent bays are seldom studied over long periods, nobody knows what has prompted the dinoflagellates to either leave the bay or diminish their magical bluish-green glow.
And nobody knows if and when the bay’s shimmer will come back to full strength. Some bioluminescent bays in the Caribbean and beyond, including Laguna Grande in Fajardo, P.R., have gone dark temporarily and then resumed full strength (sometimes big storms are to blame for the blackouts). Others come back with more erratic glows. A few have turned off altogether.
Saving Mosquito Bay is critical, scientists and government officials said. Only a handful of prized bioluminescent bays exist in the Caribbean, and a few more lie in the Pacific. Their numbers fluctuate as some die out and others take their place, and many only offer a seasonal glow. For the dinoflagellate to thrive, conditions must be just right. Mosquito Bay is optimal: warm and shallow with stable winds and ringed by red mangroves, which feed the plankton.
“They are a very rare and a unique ecosystem, and without proactive management, they just won’t stick around,” said Michael Latz, a marine biologist at the Scripps Institution of Oceanography at the University of California, San Diego, who has studied bioluminescent bays for three decades. “The question is how resilient are the dinoflagellates and does bioluminescence come back. You cross your fingers and hope it will.”
For now, natural causes, including a wind shift, rank high among prevailing theories. But other culprits are also being studied, among them sediment from the long rutted dirt road that leads vehicles to the bay and the effects of too many people kayaking in the bay.
In Puerto Rico, government officials are scrambling to preserve the bay’s glow for environmental and economic reasons. Mosquito Bay is the most popular and lucrative tourist attraction in Vieques, an impoverished island of 9,000 residents with few businesses but an abundance of crystalline beaches.
Concerned by the prospect of a long-term blackout, Puerto Rico’s Department of Natural Resources has formed a task force to study and monitor the bay. And for the first time, it has curtailed use of the bay.
Until at least the end of June, and perhaps beyond, only licensed operators can bring kayakers to the bay, and only Friday through Sunday. This will give the bay breathing room and allow scientists to study it undisturbed, government officials said.
Other strict measures are also being put in place. Park rangers are now counting the number of people who visit the small bay and are keeping a close watch of it at night to ensure that rules — for example, no swimming, as of several years ago — are being followed. And the government is improving the dirt road.
“We know the bay is not behaving consistently, and for that we need to study and investigate,” said Carmen Guerrero Pérez, secretary of the Department of Natural Resources.
While no conclusions have yet been drawn, Dr. Latz said one reason for the loss of bioluminescence may be a shift in wind direction to the north last winter. Strong winds from that direction would push the dinoflagellates (which cannot swim against the current) out of the bay’s narrow mouth back into the Caribbean Sea. These strong winds in January and March also made the bay extremely turbid, which interferes with bioluminescence.
Ms. Guerrero said she was skeptical that the daily visitors, numbering in the hundreds, were the cause. “We would have seen it before if it were directly tied to that,” she said.
On this island, which for 50 years was home to a highly contentious Navy bombing range, the finger-pointing over the dimming of the bay has also become a proxy battle between business owners and locals, who are historically wary of outside involvement here.
Carlos Prieto, a lifelong fisherman who studied biology, said he blamed an increase in the number of government permits to tour operators and the lack of oversight for the dimming. Viequenses, he said, are also upset because they can only visit the bay now if they pay a tour operator.
“All of this increases turbidity and brings changes to the bay, but they continue to give them permission for tourists to come,” he said. “These decisions are all made from far away.”
Business owners said they, too, were caretakers of the bay, and they expressed frustration at the lack of answers and the blame shifting. Business has suffered greatly since the dimming and the moratorium, said Bryan Jahnke, the owner of Black Beard Sports, which is allowed to take 20 kayakers a day out to the bay.
“It’s become an us-versus-them issue,” he said. “Action or inaction, we are stuck in the middle of this. But the mandate should be that we find out what the problem is to prevent it from happening in the future.”
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