Large Orange Mass in Gulf Algal Bloom, Not Oil, Conclude LSU Scientists

Release Date: 10/27/2010

Independent tests indicate orange mass off Tiger Pass not related to spill; final results still pending.

Tests conducted at the Louisiana State University (LSU) departments of Oceanography and Coastal Sciences, and Environmental Sciences concluded today that a large mass of orange substance near Tiger Pass in the Mississippi Delta is an algal bloom, not oil. Scientists tested samples collected over the weekend by Louisiana Department of Wildlife and Fisheries (LDWF) staff for any accumulation of oil among the phytoplankton.

According to analysis by Dr. Sibel Bargu, Assistant Professor at LSU’s Department of Oceanography and Coastal Sciences and a specialist in algae, and by the laboratory of Dr. Ed Overton, Professor Emeritus for the Department of Environmental Sciences, the large orange mass identified and sampled by LDWF biologists in the area near Tiger Pass is an algal bloom.

“Large algal blooms are common occurrences in the Gulf of Mexico when we experience warm weather, particularly from May to November,” said LDWF Assistant Secretary Randy Pausina. “This summer, we have all been acutely aware of possible impacts from the oil spill, which make us take a closer look at events like this one that might normally go unnoticed in our state waters. That is why we pursued testing the algal bloom to ensure that it was phytoplankton and not oil from the BP oil spill.”

Dr. Overton’s lab, which specializes in petroleum analysis, did conclude that there were some extremely low levels of hydrocarbons present in the samples – a finding that is consistent with normal water samples in the northern Gulf of Mexico. Hydrocarbons are common in samples taken at the surface, as the algal bloom samples were, and typically accumulate over time from natural oil seeps, waterway discharges, boat byproducts and various forms of industrial runoff.

Early reports about an orange substance in federal waters southwest of the Southwest Pass of the Mississippi River were made to the U.S. Coast Guard last week, and they were the first to investigate the claims that the mass was oil. Once the substance was reported within state waters, LDWF biologists investigated the algal bloom and collected samples for independent testing at LSU. The conclusions from professors Overton and Bargu are consistent with the assumption made by the Coast Guard that the mass was a large algal bloom rather than oil from the Deepwater Horizon oil spill.

The Department of Wildlife and Fisheries is charged with managing and protecting Louisiana's abundant natural resources. For more information, visit us at www.wlf.louisiana.gov on Facebook at www.facebook.com/pages/Baton-Rouge-LA/Louisiana-Department-of-Wildlife-a... or follow us on Twitter @LDWF.

For more information, please contact Olivia Watkins at 225-610-8660 or owatkins@wlf.la.gov.

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