Fuente: REALscience
Expuesto el: miércoles, 09 de mayo de 2012 21:46
Autor: Michael Bradbury
Asunto: Dolphin, Pelican Die-Off in Peru Puzzles Scientists
| Peru is ill-equipped to handle a coastal environmental emergency. Almost 900 dolphins washed ashore on the nation’s northern beaches this winter and their deaths still remain a mystery, in part because the country lacks all the tools to test for diseases. Necropsies weren’t conducted in a timely manner as the animals showed up on beaches between January and April. By waiting too long to study the carcasses, biologists think that vital clues about the stranding may have been lost. Before the dolphin disaster was over, pelicans began dying in record numbers along the same beaches, triggering concern from beach-goers and fishermen. Though it is fall in Peru and the prime tourist season is over, many surfers hang ten along 1,500 miles of coastline. And many Peruvians make their living from the sea and are worried that what might be harming dolphins and pelicans may also harm people. But several leading scientists believe that the dolphin die-off and pelican deaths are completely unrelated.
One of Almost 900 Dead Dolphins along the Peruvian Coast, Photo Courtesy of Hardy JonesOne of Almost 900 Dead Dolphins along the Peruvian Coast, Photo Courtesy of Hardy Jones The Peru-based Organization for Research and Conservation of Aquatic Animals did 30 dolphin necropsies from some of the first cetaceans to wash ashore on February 12. Carlos Yaipen-Llanos, the group’s director, says they had broken ear bones, collapsed livers and internal hemorrhages, all signs of acoustic explosions. He tells the Associated Press, “In microscopic exams we found fatty tissue with a great quantity surrounding bubbles and hemorrhages. This happens when there is a strong sound in the fatty tissue, in the mandibular fat where sounds are received.” ORCA blames seismic sounding for oil deposits on the dolphin deaths. The Peruvian government denies that the animals died from seismic oil exploration being conducted by Houston-based BPZ Energy off the north coast of Peru between Feb. 8 and April 8. On April 27, BPZ announced a joint venture with Pacific Rubiales Energy Corp. to explore and develop offshore oil drilling in the area where the dolphins died. The company denies any involvement in the almost 900 dead dolphins.
BPZ Energy Map of Oil Exploration Block Z-1 off Coast of Peru, Courtesy of BPZ Energy Dolphin defender Hardy Jones hopped a plane to Peru to see what he termed the “greatest dolphin mortality events ever recorded.” When he arrived he joined the ORCA team and headed for the beach. In one day in late March, the team spotted over 600 dead and decomposing dolphins over an 85-mile stretch of beach. Jones says, “We had counted 615 dead dolphins and had evidence of the tragedy and necropsy samples that might shed light on what had produced this catastrophe.” But like so many marine die-offs, definitive answers are often impossible to find. When the story was first reported, a few scientists thought that earthquakes in Chile were the culprit. Some thought algae blooms or disease could be responsible. Chemical runoff and near-shore pollution couldn’t be ruled out either. But based on initial reports from Dr. Yaipen-Llanos, the acoustic explosion theory holds the most water. He tells Jones in an email from mid-February, “Now Hardy, what we found in this mass stranding is that 10 of the 17 animals found dead had broken periotic bones, that is, due to acoustic impact. The source of the impact was from the right side of the pod, since hemorrhagic internal ear was found in the right side of the stranded animals.” Other tests have ruled out heavy metal poisoning, biotoxin contamination, several common diseases and bacterial infections. But what about the pelicans? Probably unrelated to the dolphin die-off the deaths of over 4,500 pelicans along the same stretch of Peruvian coastline has people wondering what is happening to animals on the Pacific. Again, no definitive proof can be gleaned but scientists think what’s killing juvenile pelicans began in January. That’s when the anchovy fishery near Lambayeque plummeted. Daily catches of 5 tons of anchovetas a day by fishermen dwindled so almost nothing about the time they started seeing the small fish dead on beaches. Anvhovetas (the Spanish version of anchovies) require cool water. Biologist Patricia Majluf believes that tongues of warm water began driving the small fish which is the main source of food for pelicans into deep waters, where the younger birds can’t reach them. Carlos Bocanegra at the National University of Trujillo analyzed 10 dying pelicans last week and found they were starving. Many of the birds had empty digestive tracks or some evidence of fish that the birds generally don’t eat. Scientists believe that the dead and dying birds are 3-4 years old, an age when they can’t dive as deep for food as older birds.
Dead Pelicans on the Beaches in Pirua, Peru, Photo by REUTERS/Heinze Plenge Similar pelican die-offs in 1982-1983 and 1997-1998 coincided with strong El Ninos, which warm the oceans, forcing the feeder fish deeper where young birds can’t reach them. Could this be the beginning of another strong El Nino weather pattern? Bocanegra says, “We saw mass deaths along Peru’s entire coast, also associated with high sea temperatures.” He says right now ocean temperatures in the region are 10 degrees above normal for this time of year. This double marine die-off has scientists questioning Peru’s ability to handle coastal emergencies. As the dolphin disaster winds down — though rotting carcasses still line the beach — and the pelican problem ramps up health officials warned the public to stay away from beaches from Lima northward, though the Health Ministry didn’t identify a specific health issue. One economist says these die-offs highlight Peru’s lack of readiness. Juan Carlos Sueiro says, “Peru doesn’t have a policy of coastal territory management.” He calls it “probably the most backward in the entire region.” And for an area so rich in biodiversity thanks to the Humboldt Current, which funnels cold, nutrient rich water along the coastline from Chile to Peru. It is the most productive marine ecosystem in the world, as well as the largest upwelling system. That has marine biologists, like Sue Rocca, worried. She says, “One of the things we do know is just how fragile we have discovered our ecosystems have become.” These die-offs show that slight alterations to the natural environment have big consequences.
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