The effects of oil dispersants are being simulated to carry out studies. (Photo: NOAA)
Dispersants used in Gulf of Mexico oil spill disrupted the food chain: study
Friday, August 03, 2012, 04:00 (GMT + 9)
A group of researchers that conducted a study simulating the effects of oil and oil dispersants on the microbial life in the coastal areas of the Gulf of Mexico believe dispersants may have killed plankton and disrupted the Gulf’s food chain.
In the study researchers from Auburn University, the University of South Alabama, and Dauphin Island Sea Lab participated and published their results in the journal Public Library of Science.
The team simulated the effects of oil, oil and Corexit 9500A and Corexit 9500A on the development of microbial life in the surface communities that produce the coastal microbial food for coastal marine life and fish, which in turn comprise food for the fish that humans consume.
Alabama researchers pumped water from Mobile Bay into 53-gal drums, then added oil, dispersant or both in the same proportions found during the oil spill, Insurance Journal reports.
Within days, the numbers of plant-like phytoplankton and a group of microbial life called ciliates rose under an oil slick -- but skid significantly in the drums with the combination of oil and Corexit 9500A, while the numbers of bacteria shot up.
“In those tanks, all of the energy seems to get trapped in the bacterial side. There were lots of bacteria left but no bigger things. It’s like the middle part of the food web is taken away,” said lead researcher Alice Ortmann of the University of South Alabama and Dauphin Island Sea Lab.
Such events were not documented during the DeepWater Horizon oil spill because most research was centered on the effect of the oil spill in deep water.
Brian Crother, a biology professor at Southeastern Louisiana University, called the findings scary but noted their limitations given that the experiments spanned only five days.
“If these guys are on the money, they have pointed to something really disastrous happening in the Gulf,” he said.
The degradation of these life forms is expected to bring exceptionally poor fishing in the coming years -- despite advertisement of record catches since the oil spill.
Similar effects were seen in the Exxon Valdez oil spill, when the herring catch off the coast of Alaska dropped to record lows three years after the spill. There is evidence that a degradation in ciliate populations was the cause of the diminished fish populations.
“The herring population in Prince William Sound didn’t collapse until four years after the Exxon Valdez,” said Michael Crosby, senior VP for research at Mote Marine Laboratory in Sarasota, Florida. “It has never recovered. Never.”
Scientists at the sea lab are working on another study on how the oil spill affected oxygen levels in the Gulf, whose results are expected later this year, WPMI Local 15 News reports.
- 2010 oil spill still wreaking havoc on Gulf ecosystem
By Natalia Real
Photo Courtesy of FIS Member National Oceanic and Atmospheric Administration NOAA/NMFS