The sea temperature increase could be related to dolphin and pelican mortality. (Photo: NOAA/YouTube, telesurtv/FIS)
Is El Niño linked to mass dolphin and pelican mortalities?
Friday, May 11, 2012, 02:30 (GMT + 9)
Recent mass die-offs of dolphins and pelicans have prompted investigations by Peruvian scientists and questions by environmentalists about the government's ability to protect neighbouring marine life.
Investigators believe hotter-than-usual ocean temperatures have driven anchovies farther out into the sea, leaving many pelicans deprived of food. But Peruvian scientists studying the deaths of dolphins and porpoises from February to mid-April have not come to any conclusion, which they blame partly on the government's delay in recovering the bodies of dead animals from the shore and investigating the matter.
Authorities took so long to collect tissues from the mammals that crucial clues were likely lost, according to the scientist heading the dolphin death probe, Armando Hung, head of the molecular biology lab at Cayetano Heredia University, The Associated Press reports.
Many birds have dropped dead too. Patricia Majluf, a biologist and former Deputy Fisheries Minister, said that warm water has reached into coastal areas and thus pushed anchovies deeper underwater where many birds cannot reach them.
Ocean temperatures in the region, said a biologist at the National University of Trujillo, Carlos Bocanegra, are currently 6 degrees Celsius above normal for this time of year.
Regarding the dolphin die-off, lab tests have so far ruled out a host of bacterial infections as the cause, although other tests remain. Hung noted that because the dolphins’ bodies were so decomposed, it was impossible to come to a decision about a theory promoted by the sea mammal conservation group ORCA, whose director, Carlos Yaipen, believes the cetaceans died from exposure to shock waves generated by acoustic "explosions" employed to test the regional sea bed for oil deposits.
Yaipen stated at a congressional hearing this week that ORCA conducted 30 autopsies of dolphins collected from along an 80-mi stretch of coastline starting on 12 February. ORCA found broken bones in the dolphins’ ears, internal hemorrhages and collapsed livers.
"In microscopic exams we found fatty tissue with a great quantity of surrounding bubbles and hemorrhages. This happens when there is a strong sound in the fatty tissue, in the mandibular fat where sounds are received," he explained.
Government officials insist they lack evidence that the dolphin deaths are related to seismic oil exploration work carried out off northern Peru between 8 February-8 April by the Houston, US-based company BPZ Energy.
Meanwhile, the US Climate Prediction Centre (CPC) said the La Niña pattern, the cause of severe dry spells in South America, is now gone and unlikely to reappear for the rest of the year, although it remains uncertain whether El Niño will develop, Insurance Journal reports.
El Niño leads to a heating of South Pacific Ocean waters, triggering floods in South America and physical and biological changes in the oceans that affect fish distribution.
“There is considerable forecast uncertainty as to whether neutral or El Niño conditions will prevail, due largely to the inability to predict whether the warmer sea surface temperatures will result in the ocean-atmosphere coupling required for a sustained El Niño event,” the centre explained.
By Natalia Real