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Insects living in wetland grasses along Louisiana’s coast oiled in the aftermath of the 2010 BP Deepwater Horizon disaster are still dying, the result of exposure to remaining oil in the marsh almost four years later, Louisiana State University entomologist Linda Hooper-Bui said Wednesday.
BP in a response late Wednesday said any oil reaching the shoreline was stripped of compounds that might damage wildlife.
It’s still unclear exactly how the remaining oil is killing the insects, but the effects are there, Hooper-Bui said. Hurricanes and their storm surges also are likely causes of insect losses in areas where there was no oil.
But when hurricanes and surge hit areas that had been oiled in the years after the spill, in some cases they remobilized oil remaining in the marsh, she said.
“After Hurricane Isaac in 2012, it looked like someone poured motor oil on the marsh” in areas where she and her students were monitoring insects, Hooper-Bui said.
The researchers also found that insects were dying in areas where high winds and low tides resulted in exposed sediment within marshy areas, when combined with temperatures of 85 degrees or greater, she said.
The research has focused on a variety of insects and spiders, including acrobat ants, crickets, seed bugs, and katydids. Included was a study of insects held in cages atop unwatered areas in the wetlands.
Her students also have found that in those same conditions, in locations where weathered oil has formed an asphalt-like crust, when the water disappeared and the marsh warned, cracks in the asphalt formed and unweathered oil oozed to the surface.
BP spokesman Jason Ryan said, “The researchers acknowledged many unknowns related to their preliminary findings, including what process would cause levels of mapthalene and methyl-napthalene to increase over time.
“However, extensive sampling and testing conducted in 2010 indicates that weathering processes removed virtually all of these compounds from the Macondo oil before it made landfall,” Ryan said.
“The trace levels of napthalene and methyl-napthalene that remain in weathered Macondo oil are no different than background levels from other sources, and there is no known process that causes these compounds to spontaneously form from other oil constituents that are degrading.”
Hooper-Bui pointed out during her talk that those two compounds are chemicals remaining from weathered oil that were found in the areas where the ants died. But she said additional research was needed to identify other chemicals that might also be remaining from the weathered oil.
Other research: brown pelicans and oil released into the air
In a separate talk, LSU chemical engineering graduate student Paria Avij discussed recent research that indicates a small, but significant, percentage of the BP oil that reached the surface of the Gulf of Mexico were launched into the air as tiny droplets by whitecap waves.
The aerosol effect was in part the result of the use of two Corexit dispersant mixtures applied on the Gulf surface and a mile deep to turn the liquid into droplets as the oil was being released from the well, she said.
The tiny droplets could be a health hazard for both oil spill response workers who were on ships in the Gulf and for residents onshore, she sad, as they can be carried in the atmosphere by winds for distances of as much as 185 miles.
BP also responded to Avij’s presentation.
“Due to the extensive controls in place, there was little potential for worker or public exposure to oil and dispersants,” Ryan said. He said more than 30,000 air monitoring samples were collected by federal agencies and the company to evaluate the potential for human exposure to dispersant and oil compounds.
“The results showed that response worker and public exposures to oil or dispersants were well below levels that could pose a health or safety concern,” Ryan said.
However, as part of a settlement of private claims lawsuits, BP has agreed to pay what could be billions of dollars for long-term medical monitoring and treatment of individuals who claim to have been made ill by the spill or who become ill in the future.
A 2011 peer-reviewed study published in Science magazine concluded that 30 percent of the lighter oil that made its way to the surface evaporated within 10 hours, but much of that material combined with particles in the air and were found in a narrow plume stretching from the Macondo well northwest towards the mouth of the Mississippi River.
Heavier compounds representing between 10 and 20 percent of oil also made their way to the surface and became aerosols, forming a much wider plume stretching across the northern edge of the oil and moving northwest towards the Louisiana coastline.
While that report doesn’t directly address the environmental and human health effects of the aerosols, lead author Joost de Gouw, a senior atmospheric scientist with the National Oceanic and Atmospheric Administration, said the results indicated that offshore clean-up workers were exposed to both the vapors and the aerosol compounds, and the prevailing winds may have carried the aerosols onshore.
“These concentrations were high,” de Gouw said in March 2011. “They are much higher than what you and I are exposed to in cities.”
In other panels at the conference Wednesday, University of Louisiana at Lafayette biologist Paul Leberg and graduate researcher Kristin Wakeland talked about efforts being made to address the problems facing brown pelicans from the erosion of coastal barrier islands.
Leberg said more effort should be made in considering the nesting ability of pelicans and other seabirds in designing barrier island restoration projects. The height to which the islands are built and the type of material used are both important considerations for enticing birds back onto rebuilt islands to build nests, he said.
Wakeland’s research has focused on efforts made to relocate birds from islands that are rapidly disappearing to those where there’s enough land left for establishment of new roosting areas.
Both said the plants that can survive on the islands in the face of hurricane storm surges are key to the birds’ survival, with mangroves and tall, stiff grasses preferred for nesting.
Islands too close to shore can be shunned by the birds because of mammals that make their way onto their beaches, including coyotes, rats, and raccoons. Fire ants can also attack eggs.
When birds are relocated by humans as fledglings, they often require daily feeding with fish, which can result in the adult birds seeking out humans in ports or piers, which might delay or interrupt nesting.
(The State of the Coast conference lasts through Thursday. Check back here for frequent updates about speakers during the conference.)