Mystery of the black lagoon: Scientists left baffled after famous Puerto Rican water that usually glows plunges into darkness



Fajardo lagoon usually glows when organisms in the water are disturbed

For the past nine days the water in the lagoon has remained dark

Biologists don't know why it's stopped glowing and are investigating

Nearby construction work, or bad weather could be to blame



A glowing lagoon off Puerto Rico's northeastern coast has gone almost completely dark and biologists have no idea why.

The Fajardo Grand Lagoon in Las Cabezas de San Juan usually glows when bioluminescent organisms that live in the water are disturbed, yet they have not been visible for at least nine days.



Nearby construction work is thought to have caused disruption to the area, but biologists also believe a recent spate of bad weather could have caused the glowing lagoon to dull.



The Fajardo Grand Lagoon, pictured, usually glows when bioluminescent organisms are disturbed, but has been dark for at least nine days. Scientists are unsure why but theories suggest nearby construction work may have disrupted water in the lagoon. It went dark in 2003 before glowing again a few months later

WHY DID THE LAGOON GLOW?

The bioluminescent lagoon is often referred to as a bay and is a popular tourist attraction.

Visitors row kayaks or take boat trips from the nearby city of Fajardo in Las Cabezas de San Juan to watch the water glow.

The lagoon is filled with one-celled organisms said to be half-animal and half-plant called dinoflagellates that glow like fireflies when the water is disturbed.

These organisms are bioluminescent thanks to an enzyme called luciferase. The name comes from Lucifer and is Latin for lucem ferrem, which means 'light-bearer'. Bioluminescent organisms can regulate how much light they produce by using different lucieferases in a range of ways.

In the Fajardo lagoon, a greenish-blue light swirls off hands and arms as visitors trail them through the water and the glow increases when boats are sailed through it.



Another theory is the chopping down of mangrove trees in the area, to let larger boats into the lagoon and its surrounding water, could also have played a part.



'We have been compiling data,' Carmen Guerrero, secretary of the Department of Natural Resources said. 'There are a lot of factors that could be at play.'

The bioluminescent lagoon is often referred to as a bay and is a popular tourist attraction.



Visitors row kayaks or take boat trips from the nearby city of Fajardo to watch the water glow.



The lagoon is filled with one-celled organisms said to be half-animal and half-plant that glow like fireflies if the water is disturbed.



A greenish light swirls off hands and arms as visitors trail them through the water.

However, the bioluminescence has dropped so significantly, tour operators have had to cancel trips and reimburse visitors, Guerrero added.

Fajardo Mayor Anibal Melendez blamed surface runoff caused by nearby construction of a water and sewer treatment plant.



He has since asked that the plant be moved elsewhere, yet officials involved with the plant deny the work is causing the lagoon's problems and the government Environmental Quality Board added the treatment plant has adequate erosion and sediment controls that 'comply with environmental standards.'

There are three lagoons in Puerto Rico that glow like the one in Fajardo and are referred to as 'bio bays.' Each lagoon is filled with organisms called dinoflagellates that glow like fireflies when the water is disturbed. These cause a greenish-blue light to appear when boats sail through it

Recent rains and a storm that are generating heavy waves is another possibility for affecting the lagoon's bioluminescence (pictured here, before the blackout)

As a preventive measure, the government has temporarily suspended construction at the project for two weeks until scientists can figure out what is causing the problem.

Alberto Lazaro, president of the state Water and Sewer Authority, said he will evaluate scientists' findings before deciding how to proceed in several weeks.



Recent rains and a storm that are generating heavy waves is another possibility for affecting the lagoon's bioluminescence, continued Guerrero.

The Conservation Trust of Puerto Rico, which manages the lagoon and surrounding areas, collects water samples three times a week to record data including temperature, salinity and precipitation.



Scientists will analyse this data to help solve the mystery of the darkening lagoon.

