Carlos Jiménez points to two photos hanging on the wall of his narrow office at the University of Costa Rica.
“I took this picture in 1995,” he says, pointing to the image of a diver hovering over a blooming slice of coral reef. “And then I took this picture four months ago.”
The second photo shows the same area, but the corals look lifeless and grey. “After the red tides all the corals were totally wiped out.”
Jiménez, who studies Costa Rica’s coral reefs at UCR, witnessed firsthand the disintegration of reefs in the northern Pacific coast’s Gulf of Papagayo, in the northwestern Guanacaste province, during a series of red tides in 2007. What worries him now is that they don’t seem to be recovering.
“The corals I reported as survivors in December, now they’re dead,” he says. Jiménez and two other researchers were awarded an emergency grant to go back to the region and evaluate why the corals are not recovering. They leave in a couple of weeks.
From the BrumelIslands to the MurciélagoIslands off the coast of Guanacaste, Jiménez says the red tides, which were brought to his attention in September 2007, have seriously damaged many reefs. The flooding from heavy rains in June and July of this year reinitiated the cycle, causing more runoff to enter the ocean and encouraging the growth of algae.
“Seeing the decline and the deterioration in the reef diversity and complexity, of course, it’s frustrating,” he says.
Still, Jiménez views Costa Rica a treasure trove of uncharted underwater land, ready to explore.
Last year, while researching in the Gulf of Papagayo, they discovered a 1-kilometerlong reef, called Matapalos, which Jiménez says was not hit as hard by the red tides.
The 2007 red tide had complex roots. Freshwater flooding from a stormy season brought in more sediment to the ocean, El Niño passed through, and more untreated sewage entered the water before the situation became critical. Increases in tourism and tourist diving have also been blamed for some coral reef damage in the area.
Jeff Vargas, of Costa Rica Adventures, has been diving for years with his father, Mario Vargas, who owned his own diving business in Ocotal on the Gulf of Papagayo.
“My father tried to avoid going to the same place every time for a dive (to reduce human impact on the area), but now there are so many dive operations that the dive sites are overflooded,” Vargas says.
Vargas’ father now makes documentaries about coral reefs and has gone with Jiménez on some of his dives. Jiménez says the local diving community was the first to raise the red flag about the red tides in the area.
Yet Jiménez has also felt some negative impact from the influx of divers.
One of his experiments in the area involves removing corals and injecting them with a colorful dye. He then replaces the corals and leaves them for a year. When the scientists go back to pick them up, they can see how much the coral has grown by measuring the space between the colorful line and the top of the coral.
But the beauty of the colored corals was too much for some visitors to resist.
“Divers, fishermen and lobster catchers steal our experiments,” Jiménez says.
Jiménez has also recently found damage to coral reefs in Cahuita, on the CaribbeanCoast.
Jiménez keeps his favorite specimen that no longer grows, called musa angulosa, in a box in his office. “In 25 years, they were gone.”
What Is a Red Tide?
Red tides, or algal blooms, are caused by an influx of microscopic algae in the water that be red, brown or green. They are visible on the water’s surface when they clump together in patches. Harmful types of this phytoplankton suck up oxygen and release toxins, killing marine life. Scientists have identified the harmful algae in the Gulf of Papagayo as cochlodinium polykrikoides, a marine plankton that produces fish-killing mucus. The causes of red tides are often difficult to pinpoint. An influx of sewage, warmer waters and increased freshwater during a rainy season are believed culprits.