Mote Study: BP Oil Spill Cleaning Chemical Kills Coral

A Mote Marine Laboratory study of the cleaning agent Corexit 9500 showed that the cleaning agent in BP oil spill disaster also caused great harm to coral.

A new report from Mote Marine Laboratory in Sarasota released Wednesday reports that cleanup efforts from the Deepwater Horizon oil rig disaster could be causing a real threat to fragile coral reefs.

The study focused on studying coral larvae and seeing how a dispersant that is used to cling to oil slicks and diffuse it from reaching shores could actually be just as toxic. The findings are published in the peer-reviewed journal PLOS ONE.

The 2010 BP disaster spilled more than 200 million gallons of oil into the Gulf of Mexico and responders used these dispersants, one called Corexit 9500, to prevent the oil from reaching beaches.

"Overall, these findings indicate that exposure of coral larvae to the dispersant Corexit 9500 is toxic and will result in loss of coral recruitment," the study states.

It turns out that the dispersant is just as harmful to certain marine life as the oil itself.

“Dispersant, and the mixture of oil and dispersant, may be highly toxic to coral larvae and prevent them from building new parts of the reef,” said Dr. Kim Ritchie, principal investigator on the emergency Protect Our Reefs grant supporting this study and manager of the Marine Microbiology Program at Mote. “In addition, our results support the growing knowledge that certain coral species may fare worse than others during oil spills.” 

Mote scientists looked to study the effects of two Florida Keys coral species—mustard hill coral and mountainous star coral—and placing larvae of these corals in different sets of solutions. 

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The test solutions include saltwater plus Dissolved Deepwater Horizon oil from the rig, weathered oil, Corexit 9500 and a final one with the oil and the Corexit 9500. The coral larvae was placed in various concentrations of solutions for 72 hours while the mountainous star coral larvae was tested in slowly diluted solutions during a 96-hour period, according to Mote.

As expected, the larvae exposed to oil died sooner than ones only in seawater, and the mountainous star coral had a lower chance of surviving in the lowest oil concentration tested of .49 parts per million diluted over that 96-hour window, according to the study.

Even worse was the Corexit 9500—the very chemical that many hoped would clean up the oil and save marine life. 

No mountainous star coral larvae settled or survived at the medium and high concentrations of 50 and 100 parts per million and no mustard hill coral larvae settled or survived at 100 parts per million.

The study says that most of the mountainous star coral didn't even survive the lowest concentration test of .86 parts per million.

What do these scientific measurements mean to the naked eye?

"Depending on the concentration, the higher the concentration of oil and dispersant, the more opaque it becomes.  With the dispersant only (Corexit 9500), there was little cloudiness and with the water soluble oil mixture (WAF) it was perfectly clear," said Dr. Dana Wetzel, manager of Mote's Environmental Laboratory for Forensics. So it's not exactly water that humans would be fond of interacting with either.

The water soluble oil mixture is the chemicals from the oil that are able to dissolve in water; oil has many different chemical components, Wetzel continued to explained.

Fresh oil from Deepwater Horizon also started killing the larvae within the first 24 hours, according to the study.

Ritchie led the investigation along with Wetzel, Dr. Gretchen Goodbody-Gringley, former Mote postdoctoral researcher who is now an instructor at Bermuda Institute of Ocean Sciences, and were conducted both in Sarasota and at the Mote Tropical Research Laboratory on Summerland Key.

"The decision to use dispersant chemicals poses trade-offs for oil spill responders. While a dispersed surface oil slick is rendered less likely to reach the shore, treatment of major oil spills with dispersant chemicals has been shown to result in significant environmental degradation as a result of increased hydrocarbon dissolution and surfactant toxicity," the team wrote in their study.

Wetzel said what this study does is provide information on how oil and dispersants effect coral larvae because that wasn't available before. Scientists have known how fish and shellfish were damaged though.

The Florida Keys coral were not directly affected by Deepwater Horizon, according to the study, but these types of coral are also found in the Northwestern Gulf closer to the oil rig, but those coral were not directly affected either, according to the study. 

Scientists believe, however, that oil exploration near Cuba could pose further harm.

“To understand how oil and dispersant could affect wild corals, more research is needed on their complex natural life cycles,” Ritchie said. “Coral larvae seem to settle with help from landing pads called ‘biofilms’ that are formed by microbes like marine bacteria. This delicate natural process might be interrupted by dispersant and its mixture with oil, so it’s important to know how it works in detail.”

BP settled in November with the federal government in for $4.5 billion for its role in the spill. Sarasota County hopes it can claim $5.25 million from the case. 

The owner of the rig itself, Transocean Ltd., was due in New Orleans federal court Wednesday to pay a $400 million settlement with the Justice Department for violating the Clean Water Act, the Associated Press reported

Richard M. Swier January 10, 2013 at 01:12 PM
So, let me understand this study. The idea should be not to clean up the oil spill and let nature take its course. Let the oil spilled disperse naturally and clean it up on shore. Drilling for oil in the gulf will continue. Oil seeps naturally from fissures in the gulf floor and it has seeped for tens of thousands of years. I would like Mote to not fix blame but rather fix the problem. What is a better way to disperse spilled oil?? I would prefer they spend their time and our taxpayers money on finding solutions.
kate January 10, 2013 at 02:21 PM
you have to understand the problem to find a solution. in all the time the oil companies spent drilling, they never spent a dime studying the environment or what it would take to repair the damage of a worst-case scenerio. finally, at least, Mote is stepping in to do the work the oil companies should have been doing from the beginning.
Randy Moore January 10, 2013 at 03:11 PM
The study doesn't slam anyone. It presents insights about the effect of chemical dispersants on coral larvae. Science does not set policy; it provides information that resource managers and elected representatives can use for making informed decisions. Perhaps knowing that dispersants can harm coral larvae may reduce the use of dispersants in the future. It might even spark the ingenuity of new and better products. Mote is not equipped to "fix the problem." The bigger question is why do policy leaders wait for disasters to hold corporations accountable for sensible environmental stewardship. The BP Oil Disaster was bad news for the Gulf Coast eco-system and that will be substantiated with many more studies over the next decade.
Greg January 10, 2013 at 03:16 PM
The article starts off with "(study) showed that the cleaning agent in BP oil spill disaster also caused great harm to coral" However, way down at the bottom of the article is the conclusion: "The Florida Keys coral were not directly affected by Deepwater Horizon, according to the study, but these types of coral are also found in the Northwestern Gulf closer to the oil rig, but those coral were not directly affected either, according to the study." It caused great harm to them without directly affecting any of them. Got it. Gotta love the media.
do-gooder January 10, 2013 at 08:54 PM
The coral has been killed everywhere the Gulfstream has carried the oil and dispersant. This toxic mess has a life of 1600 years. The oyster larvae cannot survive in the Oil and Corexit either. Why not ban the use of Corexit until it can be shown that there are no deleterious effects on the water, air, land, marine, animals and human life? Now, the EPA and BP say they don't know if Corexit is bad because there has never been a study of the impact of Corexit on life, air, land and water. This will certainly have the (desired) effect of reducing the population of the planet.
David Prior January 11, 2013 at 01:34 AM
The only way to clean up the ocean after an oil spill is to remove the oil physically from the sea. Dispersants are the opposite of cleaning. Burning is the opposite of cleaning; it leaves unburnt oil and residue in the sea and pollutes the air (and the black carbon etc settles back down into the sea, or your backyard). Extreme Spill Technology and SpillGreen are techniques that actually get the oil out of the ocean.
Greg January 11, 2013 at 03:49 PM
There are no data to support your statements do-gooder. The oyster and shrimp fishery were the best ever in 2011. Do you know why? They were closed to fishing for a long time, which has a far greater impact to the fisheries. You must have missed the part of the study saying there was no effect to coral in the keys or the gulf. Coral larval recruitement is best predicted by adult colonies living immediately adjacent, not by larvae in the current. This means if adult colonies in the keys were not affected, than neither is larval recruitement. I have references if you like.
Greg January 11, 2013 at 03:58 PM
There have been many many studies of Corexit Do-gooder. If you have a local university go and do some computer searches. Anything is toxic to coral, including pure water. If placed in a jar in the lab, everything kills coral at the concentrations used in this study, including dish soap, soda, orange juice, you name it. If we could pour orange juice on the oil and make the slick disperse, then people probably wouldnt care. The reason oil is dispersed is to a) keep it from piling up three feet thick on tourist beaches, and b) turn it into millions of small droplets thereby increasing the surface area available for the breakdown processes...such as biodegredation, photooxidation, adsportion, evaporation, etc etc etc. It is broken down by natural processes much more rapidly.The fear is unfounded as the studies have bourne out.
Florence Tracy June 26, 2013 at 02:00 AM
A product that is similar to kitty litter called Oil Dry can be used to absorb most of the spilled oil. use dry cloths to remove the oil.
Florence Tracy July 24, 2013 at 02:05 AM
Nice post with useful information which is useful for everyone thanks for sharing with us. i also know about some new oil/chemical spill control site that provide you better results in <a title="spill cleanup" href="http://ternenv.com"> spill cleanup</a> with their effective products.


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