The largest oil spill on open water to date and other environmental factors led to the historically high number of dolphin deaths in the Gulf of Mexico, concludes a two-year scientific study released today.
A team of biologists from several Gulf of Mexico institutions and the University of Central Florida in Orlando published their findings in the journal PLoS ONE.
For the past two years, scientists have been trying to figure out why there were a high number of dolphin deaths, part of what's called an "unusual mortality event" along the northern Gulf of Mexico.
Most troubling to scientists was the exceptionally high number of young dolphins that made up close to half of the 186 dolphins that washed ashore from Louisiana to western Florida from January to April 2011. The number of "perinatal" (near birth) dolphins stranded during this four-month period was six times higher than the average number of perinatal strandings in the region since 2003 and nearly double the historical percentage of all strandings.
"Unfortunately it was a 'perfect storm' that led to the dolphin deaths," said Graham Worthy, a UCF provosts distinguished professor of biology and co-author of the study. "The oil spill and cold winter of 2010 had already put significant stress on their food resources, resulting in poor body condition and depressed immune response. It appears the high volumes of cold freshwater coming from snowmelt water that pushed through Mobile Bay and Mississippi Sound in 2011 was the final blow."
The cold winter of 2010 was followed by the historic BP Deepwater Horizon disaster in April 2011, which dumped millions of gallons of oil into the Gulf of Mexico, likely disrupting the food chain. This was in the middle of the dolphins' breeding season. A sudden entry of high volumes of cold freshwater from Mobile Bay in 2011 imposed additional
|Contact: Zenaida Kotala|
University of Central Florida