NOAA's Response and Restoration Blog

An inside look at the science of cleaning up and fixing the mess of marine pollution


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From Natural Seeps to a Historic Legacy, What Sets Apart the Latest Santa Barbara Oil Spill

Cleanup worker and oiled boulders on Refugio State Beach where the oil from the pipeline entered the beach.

The pipeline release allowed an estimated 21,000 gallons of crude oil to reach the Pacific Ocean, shown here where the oil entered Refugio State Beach. (NOAA)

The response to the oil pipeline break on May 19, 2015 near Refugio State Beach in Santa Barbara County, California, is winding down. Out of 20 area beaches closed due to the oil spill, all but one, Refugio State Beach, have reopened.

NOAA’s Office of Response and Restoration provided scientific support throughout the response, including aerial observations of the spill, information on fate and effects of the crude oil, oil detection and treatment, and potential environmental impacts both in the water and on the shore.

Now that the response to this oil spill is transitioning from cleanup to efforts to assess and quantify the environmental impacts, a look back shows that, while not a huge spill in terms of volume, the location and timing of the event make it stand out in several ways.

Seep or Spill: Where Did the Oil Come From?

This oil spill, which allowed an estimated 21,000 gallons of crude oil to reach the Pacific Ocean, occurred in an area known for its abundant natural oil seeps. The Coal Oil Point area is home to seeps that release an estimated 6,500-7,000 gallons of oil per day (Lorenson et al., 2011) and are among the most active in the world. Oil seeps are natural leaks of oil and gas from subterranean reservoirs through the ocean floor.

The pipeline spill released a much greater volume of oil than the daily output of the local seeps. Furthermore, because it was from a single source, the spill resulted in much heavier oiling along the coast than you would find from the seeps alone.

A primary challenge, for purposes of spill response and damage assessment, was to determine whether oil on the shoreline and nearby waters was from the seeps or the pipeline. Since the oil from the local natural seeps and the leaking pipeline both originated from the same geologic formation, their chemical makeup is similar.

However, chemists from Woods Hole Oceanographic Institution, the University of California at Santa Barbara, Louisiana State University, and the U.S. Coast Guard Marine Safety Lab were able to distinguish the difference by examining special chemical markers through a process known as “fingerprinting.”

Respecting Native American Coastal Culture

The affected shorelines include some of the most important cultural resource areas for California Native Americans. Members of the Chumash Tribe populated many coastal villages in what is now Santa Barbara County prior to 1800. Many local residents of the area trace their ancestry to these communities.

To ensure that impacts to cultural resources were minimized, Tribal Cultural Resource Monitors were actively engaged in many of the upland and shoreline cleanup activities and decisions throughout the spill response.

Bringing Researchers into the Response

The massive Deepwater Horizon oil spill in the Gulf of Mexico in 2010 highlighted the need for further research on issues surrounding oil transport and spill response. As a result, there was a great deal of interest in this spill among members of the academic community, which is not always the case for oil spills. In addition, the spill occurred not far from the University of California at Santa Barbara.

From the perspective of NOAA’s Office of Response and Restoration, this involvement with researchers was beneficial to the overall effort and will potentially serve to broaden our scientific resources and knowledge base for future spills.

The Legacy of 1969

Another unique aspect of the oil spill at Refugio State Beach was its proximity to the site of one of the most historically significant spills in U.S. history. Just over 46 years ago, off the coast of Santa Barbara, a well blowout occurred, spilling as much as 4.2 million gallons of oil into the ocean. The well was capped after 11 days.

The 1969 Santa Barbara oil spill, which was covered widely in the media, oiled miles of southern California beaches as well. It had such a devastating impact on wildlife and habitat that it is credited with being the catalyst that started the modern-day environmental movement. Naturally, the 2015 oil spill near the same location serves as a reminder of that terrible event and the damage that spilled oil can do in a short period of time.

Moving Toward Restoration

In order to assess the environmental impacts from the spill and cleanup, scientists have collected several hundred samples of sediment, oil, water, fish, mussels, sand crabs, and other living things. In addition, they have conducted surveys of the marine life before and after the oil spill.

The assessment, which is being led by the state of California, involves marine ecology experts from several California universities as well as federal and state agencies.

After a thorough assessment of the spill’s harm, the focus will shift toward restoring the injured natural and cultural resources and compensating the public for the impacts to those resources and the loss of use and enjoyment of them as a result of the spill. This process, known as a Natural Resource Damage Assessment, is undertaken by a group of trustees, made up of federal and state agencies, in cooperation with the owner of the pipeline, Plains All American Pipeline. This group of trustees will seek public input to help guide the development of a restoration plan.


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How Do Oil Spills out at Sea Typically Get Cleaned Up?

This is a post by Kate Clark, Acting Chief of Staff with NOAA’s Office of Response and Restoration.

Close up of skimming device on side of a boat with oil and boom.

Skimmers come in various designs but all basically work by removing the oil layer from the surface of the water. (U.S. Coast Guard)

Whether for hanging a picture on the wall or fixing a leaky faucet, most people keep a common set of tools in their home. While some tools get more use than others, it’s good to have an array on hand to handle most repair jobs. The same is true for responding to oil spills.

Like a home repair job, each oil spill has unique aspects that call for careful consideration when deciding which tool to use. Responders keep an array of response methods in their toolkit for dealing with oil in offshore waters: skimming and booming, in situ burning, and applying dispersants.

Let’s get to know a few of those tools and the situations when they might be the most appropriate method for dealing with oil spills out at sea.

Skimming: Take a Little off the Top

Skimming is a process that removes oil from the sea surface before it reaches sensitive areas along a coastline. Sometimes, two boats will tow a collection boom, allowing oil to concentrate within the boom, where it is then picked up by a “skimmer.” From whirring disks to floating drums, skimmers come in various designs but all basically work by removing the oil layer from the surface of the water. These devices attract oil to their surfaces before transferring it to a collection tank, often on a boat. Ideal conditions for skimming are during the day when the oil slick is thick and the ocean surface is fairly calm.

The success of a skimming operation is dependent on something known as the “encounter rate.” Much like a vacuum picks up dirt from your carpet, a skimmer has to come in direct contact with the oil in order to remove it from the surface and, even then, it will still pick up some water. That’s why responders will often refer to the volume of oil removed via skimming as gallons of an oil-water mixture.

In Situ Burning: Burn After Oiling

Plumes of smoke from two fires burning oil on the ocean surface.

Burning oil “in place” (in situ) on the water’s surface requires gathering a layor of oil thick enough to sustain the burn. (NOAA)

In situ burning is the process of burning spilled oil where it is on the ocean (known as “in situ,” which is Latin for “on site”). Similar to skimming, two boats will often tow a fire-retardant collection boom to concentrate enough oil to burn. Burning is sometimes also used in treating oiled marshes.

Ideal conditions for in situ burning are daylight with mild or offshore winds and flat seas. The success of burning oil is dependent on corralling a layer of oil thick enough to maintain a sustained burn. Any burn operation includes careful air monitoring to ensure smoke or residue resulting from the burn do not adversely impact people or wildlife.

Chemical Dispersants: Break It Up

Releasing chemical dispersants, usually from a small plane or a response vessel, on an oil slick breaks down the oil into smaller droplets, allowing them to mix more easily into the water column. Smaller droplets of oil become more readily available to microbes that will eat them and break them down into less harmful compounds.

However, using dispersants has its drawbacks, shifting potential impacts to the marine life living in the water column and on the seafloor. Because of this, the decision to chemically disperse oil into the water column is never made lightly. This decision is often made so that much less oil stays at the surface, where it could affect birds and wildlife at the ocean surface and drift onto vulnerable coastal habitat like beaches, wetlands, and tidal flats.

Ideal conditions for chemical dispersion are daylight with mild winds and moderate seas. Chemical dispersion is never done close to the shore, in shallow waters, near coastal communities, or when there is a potential for winds to carry the chemical spray away from its intended target.

Natural dispersion can and does occur when waves at the ocean surface have enough turbulent energy to allow surface oil to mix into the water column. Applying chemical dispersants can expedite this process when there is an imminent threat associated with allowing the oil to stay on the surface.

Graphic showing methods for responding to oil spills at sea. Plane applying chemical dispersants: Chemical dispersion is achieved by applying chemicals to remove oil from the water surface by breaking  the oil into small droplets. Burning oil surrounded by boom: Also referred to as in situ burning, this   is the method of setting fire to freshly spilled oil, usually while still   floating on the water surface. Booms: Booms are long floating barriers used to   contain or prevent the spread of spilled oil. A boat skimming oil: Skimming is achieved with  boats equipped with a floating skimmer designed to remove thin layers of oil from   the surface, often with the help of booms.One Size Does Not Fit All

You may have noticed that each of these tools has one common factor limiting its effectiveness: daylight, or more precisely, visibility. Being able to see the spilled oil, often over large areas of the ocean, is critical to being able to clean it up. That means these tools become ineffective at night, during certain seasons, or in regions where prolonged darkness, fog, or clouds are the norm.

Table showing the conditions which may affect the use of different oil spill response methods at sea (skimming, burning, dispersing). Conditions are sunlight, wind, rough seas, cold, and nearshore.

Conditions which may affect the use of different oil spill response methods at sea.

Rough seas can be prohibitive for skimming and burning since these methods rely on calm conditions and collection booms to gather (and keep) oil in one place. High winds can often rule out burning and aerial dispersion as an option.

While these techniques perform best under certain, ideal conditions, responders often have to make do with the variety of conditions going on during an oil spill and can and do use these tools under less-than-ideal conditions. Their effectiveness also depends on factors such as the type or state of the spilled oil or the environment it was spilled in (e.g., sea ice).

Just like your home repairs, the job sometimes calls for a non-traditional tool or creative fix. The continued development of alternative response methods and technologies for cleaning up oil is critical for addressing oil spills in geographic areas or conditions that the traditional toolbox is not equipped to fix.

Kate Clark is the Acting Chief of Staff for NOAA’s Office of Response and Restoration. For nearly 12 years she has responded to and conducted damage assessment for numerous environmental pollution events for NOAA’s Office of Response and Restoration. She has also managed NOAA’s Arctic policy portfolio and served as a senior analyst to the National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling.


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Who Thinks Crude Oil Is Delicious? These Ocean Microbes Do

This is a post by Dalina Thrift-Viveros, a chemist with NOAA’s Office of Response and Restoration.

Edge of oil slick at ocean surface.

There are at least seven species of ocean bacteria that can survive by eating oil and nothing else. However, usually only a small number of oil-eating bacteria live in any given part of the ocean, and it takes a few days for their population to increase to take advantage of their abundant new food source during an oil spill. (NOAA)

Would you look at crude oil and think, “Mmm, tasty…”? Probably not.

But if you were a microbe living in the ocean you might have a different answer. There are species of marine bacteria in several families, including Marinobacter, Oceanospiralles, Pseudomonas, and Alkanivorax, that can eat compounds from petroleum as part of their diet. In fact, there are at least seven species of bacteria that can survive solely on oil [1].

These bacteria are nature’s way of removing oil that ends up in the ocean, whether the oil is there because of oil spills or natural oil seeps. Those of us in the oil spill response community call this biological process of removing oil “biodegradation.”

What Whets Their Oily Appetites?

Communities of oil-eating bacteria are naturally present throughout the world’s oceans, in places as different as the warm waters of the Persian Gulf [2] and the Arctic conditions of the Chukchi Sea north of Alaska [3].

Each community of bacteria is specially adapted for the environment where it is living, and studies have found that bacteria consume oil most quickly when they are kept in conditions similar to their natural environments [4]. So that means that if you took Arctic bacteria and brought them to an oil spill in the Gulf of Mexico, they would not eat the oil as quickly as the bacteria that are already living in the Gulf. You would get the same result in the reverse case, with the Arctic bacteria beating out the Gulf bacteria at an oil spill in Alaska.

Other factors that affect how quickly bacteria degrade oil include the amount of oxygen and nutrients in the water, the temperature of the water, the surface area of the oil, and the kind of oil that they are eating [4][5][6]. That means the bacteria that live in a given area will consume the oil from a spill in the summer more quickly than a spill in the winter, and will eat light petroleum products such as gasoline or diesel much more quickly than heavy petroleum products like fuel oil or heavy crude oil.

Oil-eating microbes fluorescing in a petri dish.

This bacteria, fluorescing under ultraviolet light in a petri dish, is Pseudomonas aeruginosa. It has been used during oil spills to break down the components of oil. (Credit: Wikimedia user Sun14916/Creative Commons Attribution-ShareAlike 3.0 Unported license)

Asphalt, the very heaviest component of crude oil, is actually so difficult for bacteria to eat that we can use it to pave our roads without worrying about the road rotting away.

What About During Oil Spills?

People are often interested in the possibility of using bacteria to help clean up oil spills, and most oil left in the ocean long enough is consumed by bacteria.

However, most oil spills last only a few days, and during that time other natural “weathering” processes, such as evaporation and wave-induced breakup of the oil, have a much bigger effect on the appearance and location of the oil than bacteria do. This is because there are usually only a small number of oil-eating bacteria in any given part of the ocean, and it takes a few days for their population to increase to take advantage of their abundant new food source.

Because of this lag time, biodegradation was not originally included in NOAA’s oil weathering software ADIOS. ADIOS is a computer model designed to help oil spill responders by predicting how much of the oil will stay in the ocean during the first five days of a spill.

However, oil spills like the 2010 Deepwater Horizon well blowout, which released oil for about three months, demonstrate that there is a need for a model that can tell us what would happen to the oil over longer periods of time. My team in the Emergency Response Division at NOAA’s Office of Response and Restoration has recognized that. As a result, version 3 of ADIOS, due to be released later in 2015, will take into account biodegradation.

My team and I used data published in scientific journals on the speed of oil biodegradation under different conditions to develop an equation that can predict how fast the components of oil will be consumed, and how the speed of this process can change based on the surface area-to-mass ratio of the oil and the climate it is in. A report describing the technical details of the model will be published in the upcoming Proceedings of the Arctic and Marine Oilspill Program Technical Seminar, which will be released after the June conference.

Including oil biodegradation in our ADIOS software will provide oil spill responders with an even better tool to help them make decisions about their options during a response. As part of the team working on this project, it has provided me with a much greater appreciation for the important role that oil-eating bacteria play in the long-term effort to keep our oceans free of oil.

I know I’m certainly glad they think oil is delicious.

Dalina Thrift-ViverosDalina Thrift-Viveros is a Seattle-based chemist who has been providing chemistry expertise for Emergency Response Division software projects and spill responders since 2011, when she first started working with NOAA and Genwest. When she is not involved in chemistry-related activities, Dalina sings with the rock band Whiskey River and plays sax with her jazz group, The Paul Engstrom Trio.

Literature cited

[1] Yakimov, M.M., K.N. Timmis, and P.N. Golyshin. “Obligate oil-degrading marine bacteria,” Current Opinion in Biotechnology, 2007, 18(3), pp. 257-266.

[2] Hassanshahian, M., G. Emtiazi, and S.Cappello. “Isolation and characterization of crude-oil-degrading bacteria from the Persian Gulf and the Caspian Sea,” Marine Pollution Bulletin, 2012, 64, pp. 7–12.

[3] McFarlin, K.M., R.C. Prince, R. Perkins, and M.B. Leigh. “Biodegradation of Dispersed Oil in Arctic Seawater at -1°C,” PLoS ONE, 2014, 9:e84297, pp. 1-8.

[4] Atlas, R.M. “Petroleum Biodegradation and Oil Spill Bioremediation,” Marine Pollution Bulletin, 1995, 31, pp. 178-182.

[5] Atlas, R.M. and T.C. Hazen. “Oil Biodegradation and Bioremediation: A Tale of the Two Worst Spills in U.S. History,” Environmental Science & Technology, 2011, 45, pp. 6709-6715.

[6] Head, I.M., D.M. Jones, and W.F.M. Röling, “Marine microorganisms make a meal of oil,” Nature Reviews Microbiology, 2006, 4, pp. 173-182.


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On the Front Lines of an Oil Spill in My Own Backyard: A Report from Santa Barbara, California

This is a post by Gabrielle Dorr, NOAA/Montrose Settlements Restoration Program Outreach Coordinator.

Oiled boulders on a California beach with cleanup workers in the distance.

NOAA has been involved with the May 19, 2015 oil spill resulting from a pipeline break at Refugio State Beach, near Santa Barbara, California, which released an estimated 100,000 gallons of crude oil, with a reported 21,000 gallons reaching the ocean. (Bill Stanley/U.S. Fish and Wildlife Service)

When I first heard about the pipeline oil spill at Refugio State Beach near Santa Barbara, California, a couple weeks ago, I felt concerned about the fact that it was only a few hours up the coast from where I currently live and work. I couldn’t stop thinking about what the long-term impacts would be to the beautiful beaches we have here in southern California.

As a NOAA communications specialist who had cut her teeth in providing communications support for the 2010 Deepwater Horizon oil spill, I thought I knew roughly what to expect when I was called in to help in Santa Barbara.

When I was asked to provide support for that oil spill in July 2010, oil had been gushing into the ocean for several months and was washing up on beaches bordering five states far from my home in California. I was able to get out into the field in Louisiana to see firsthand what an oiled marsh looks like, but that was months after the spill began. In addition, the massive scale of the response and damage assessment efforts made it tough to grasp the full picture of the spill.

Still, it was important for me to see the impacts for myself, so that I could better tell the story about what happened and what NOAA and our partners were going to do to make it right.

From the Gulf of Mexico to Southern California

Fish being measured on a table.

After an oil spill, scientists collect lots of data on the potential impacts of the oil and response efforts to fish, birds, and wildlife. (NOAA)

This time, at Refugio State Beach, was different. I was stationed at a command center for those working to assess the environmental impacts of the spill only three days after a pipeline released up to 105,000 gallons of oil, with at least 21,000 gallons reaching the Pacific Ocean north of Santa Barbara.

From the start of this oil spill, I was able to see the inner workings of the Natural Resource Damage Assessment process and how complex and challenging this process can be for the scientists involved. Biologists, armed with notebooks and cameras, were diligently filling out paperwork and going over every painstaking detail of their data. Collecting good data is extremely important at this early stage because it will be used as evidence showing the oil spill’s potential impacts to wildlife and natural areas.

The next day I was asked to follow a team into the field to take photos of them collecting fish samples from one of the oil spill’s “hot zones.” At the stretch of Refugio State Beach where the majority of the oil cleanup activities were taking place, it was easy to be overwhelmed by the scene. There were a huge number of trucks, cars, buses, people in hard hats, reporters, and even an eating area with eight large tables set up under tents.

That day I was part of a team of nine people who would be sampling fish for oil contamination, with representatives from NOAA, the National Park Service, California Department of Fish and Wildlife, and an environmental consulting firm representing Plains All American Pipeline, the company responsible for the leaking pipeline. When we checked in with the on-site safety officer, he told us that we would need to wear Tyvek suits, booties taped around our calves, gloves, and hard hats.

Oil and Fish Don’t Mix

Out on the beach it was hard not to step in oil since it covered most of the cobble rocks lining the beach in a thick band. I watched as the team baited their hooks and cast their lines in the water. The fishing team spread out along the beach, making the job of running buckets of samples between those catching and processing the fish even more challenging.

Once I had finished taking photos, I began shuttling buckets of fish from the edge of the contaminated zone to a picnic table several yards away. There, two women were working hard to process the samples of fish that will later be analyzed for oil contaminants in a lab.

The team caught 18 barred surfperch in total, giving us a robust sample of the local population which might have been affected by the oil spill. It was a successful day of sampling, but at the same time, I found it difficult not to think about how all of that oil was going to be cleaned off of those rocks.

Working at the front line of the oil spill at Refugio State Beach was a unique experience for me, but it also feels a little too close to home. When I was responding to the Deepwater Horizon oil spill in the Gulf of Mexico, I was stationed two hours away from the nearest coast and lived almost 2,000 miles away in California.

I found having an oil spill in your own backyard is much more personal and reminds me of how important it is to plan, train, and prepare for oil spills long before any oil hits the water.

For more information on the response to this oil spill, visit the Refugio Response Joint Information Center website.

Gabrielle Dorr

Gabrielle Dorr.

Gabrielle Dorr is the Outreach Coordinator for the Montrose Settlements Restoration Program as part of NOAA’s Restoration Center. She lives and works in Long Beach, California, where she is always interacting with the local community through outreach events, public meetings, and fishing education programs.


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Like a Summer Blockbuster, Oil Spills and Hurricanes Can Take the Nation by Storm

Wrecked sailboats and debris along a dock after a hurricane.

The powerful wind and waves of a hurricane can damage vessels, releasing their fuel into coastal waterways. (NOAA)

From Twister and The Perfect Storm to The Day After Tomorrow, storms and other severe weather often serve as the dramatic backdrop for popular movies. Some recent movies, such as the Sharknado series, even combine multiple fearsome events—along with a high degree of improbability—when they portray, for example, a hurricane sweeping up huge numbers of sharks into twisters descending on a major West Coast city.

But back in the world of reality, what could be worse than a hurricane?

How about a hurricane combined with a massive oil spill? It’s not just a pitch for a new movie. Oil spills actually are a pretty common outcome of powerful storms like hurricanes.

There are a couple primary scenarios involving oil spills and hurricanes. The first is a hurricane causing one or more oil spills, which is what happened during Hurricane Katrina in 2005 and after Hurricane Sandy in 2012. These kinds of oil spills typically result from a storm’s damage to coastal oil facilities, including refineries, as well as vessels being damaged or sunken and leaking their fuel.

The second, far less common scenario is a hurricane blowing in during an existing oil spill, which is what happened during the 2010 Deepwater Horizon oil spill.

Hurricane First, Then Oil Spills

Stranded and wrecked vessels are one of the iconic images showing the aftermath of a hurricane. In most cases those vessels have oil on board. And don’t forget about all the cars that get flooded. Each of these sources may contain relatively small amounts of fuel, but hurricanes can cause big oil spills too.

Additional damage is often caused by the storm surge, as big oil and chemical storage tanks can get lifted off their foundations (or sheared off in the case of the picture below).

A damaged boat setting on a  fuel dock.

A boat, displaced and damaged in the aftermath of Hurricane Katrina, in late summer of 2005 in the Gulf of Mexico, an area frequented by both hurricanes and oil spills. (NOAA)

Hurricanes Katrina and Rita in 2005 passed through the center of the Gulf of Mexico oil industry and caused dozens of major oil spills and thousands of small spills.

One of the largest stemmed from the Murphy Oil refinery in St. Bernard Parish, Louisiana. Dikes surrounding the oil tanks at the refinery were full from flood waters, so when a multi-million gallon tank failed, oil flowed easily into a nearby neighborhood, leaving oil on thousands of homes and businesses already reeling from the flood waters.

Hurricanes can also create navigation hazards that result in later spills. Hurricane Rita, hitting the Gulf in September 2005, sank several offshore oil platforms. While some were recovered, others were actually left missing. Several months later, the tank barge DBL 152 “found” one of these missing rigs, spilling nearly 2 million gallons of thick slurry oil after striking the sunken and displaced platform hiding below the ocean surface.

A large ship on its side, leaking dark oil on the ocean surface.

In November 2005, tank barge DBL 152 struck the submerged remains of a pipeline service platform that collapsed a few months earlier during Hurricane Rita. The double-hulled barge was carrying approximately 5 million gallons of slurry oil, a type of oil denser than seawater, which meant as the thick oil poured out of the barge, it sank to the seafloor. (Entrix)

Oil Spills and Then a Hurricane Hits

So what happens if a hurricane hits an existing oil spill?

This was a big concern during the summer of 2010 in the Gulf of Mexico. There was an ever-growing slick on the ocean surface, oil already on the shore, and lots of response equipment and personnel scattered across the Gulf cleaning up the Deepwater Horizon spill.

There was a lot of speculation as to what might happen as hurricane season began. Hurricane Alex, a relatively small storm, was the first test. The first impact came days before the storm, as response vessels evacuated the area. Hurricane Alex halted response efforts such as skimming and burning for several days. Hundreds of miles of oil booms protecting the shoreline were displaced by the growing surf.

As the hurricane passed through, floating oil was quickly dispersed by the powerful winds and waves, and the same wave energy buried, uncovered, and moved oil on the shore or in submerged mats of oil near the shoreline. Some oil was likely carried inland by sea spray and flood waters from the storm surge. Oil dissolved in the water column near the surface became even more dispersed, but the deep waters of the Gulf were well out of reach of the stormy commotion at the surface, and the leaking wellhead continued to gush.

But the Deepwater Horizon spill wasn’t the only time hurricanes have butted heads with a massive spill. In 1979, Mexico’s Ixtoc I well blowout in the southern Gulf of Mexico was hit by Hurricane Henri. The main impact of the hurricane’s winds was to dilute and weather the floating oil.

In some places along the Texas coast, beached oil was washed over the barrier islands into the bays behind them, while in other areas stranded oil was buried by clean sand. Many of these oiled areas were reworked a year later when Hurricane Allen battered the coast.

Preventing oil spills is a part of preparing for hurricanes. Coastal oil facilities and vessel owners do their best to batten down the hatches and get their vessels out of harm’s way, but we know that spills may still happen. Atlantic hurricane season, which runs from June 1 to November 30, is a busy time for those of us in oil spill response, and we breathe a sigh of relief when hurricane season ends—just in time for winter storm season to begin.


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Latest NOAA Study Ties Deepwater Horizon Oil Spill to Spike in Gulf Dolphin Deaths

Group of dolphin fins at ocean surface.

A study published in the journal PLOS ONE found that an unusually high number of dead Gulf dolphins had what are normally rare lesions on their lungs and hormone-producing adrenal glands, which are associated with exposure to oil compounds. (NOAA)

What has been causing the alarming increase in dead bottlenose dolphins along the northern Gulf of Mexico since the Deepwater Horizon oil spill in the summer of 2010? Independent and government scientists have found even more evidence connecting these deaths to the same signs of illness found in animals exposed to petroleum products, as reported in the peer-reviewed online journal PLOS ONE.

This latest study uncovered that an unusually high number of dead Gulf dolphins had what are normally rare lesions on their lungs and hormone-producing adrenal glands.

The timing, location, and nature of the lesions support that oil compounds from the Deepwater Horizon oil spill caused these lesions and contributed to the high numbers of dolphin deaths within this oil spill’s footprint.

“This is the latest in a series of peer-reviewed scientific studies, conducted over the five years since the spill, looking at possible reasons for the historically high number of dolphin deaths that have occurred within the footprint of the Deepwater Horizon spill,” said Dr. Teri Rowles, one of 22 contributing authors on the paper, and head of NOAA’s Marine Mammal Health and Stranding Response Program, which is charged with determining the causes of unusual mortality events.

“These studies have increasingly pointed to the presence of petroleum hydrocarbons as being the most significant cause of the illnesses and deaths plaguing the Gulf’s dolphin population,” said Dr. Rowles.

A System out of Balance

In this study, one in every three dead dolphins examined across Louisiana, Mississippi and Alabama had lesions affecting their adrenal glands, resulting in a serious condition known as “adrenal insufficiency.” The adrenal gland produces hormones—such as cortisol and aldosterone—that regulate metabolism, blood pressure and other bodily functions.

“Animals with adrenal insufficiency are less able to cope with additional stressors in their everyday lives,” said Dr. Stephanie Venn-Watson, the study’s lead author and veterinary epidemiologist at the National Marine Mammal Foundation, “and when those stressors occur, they are more likely to die.”

Earlier studies of Gulf dolphins in areas heavily affected by the Deepwater Horizon oil spill found initial signs of this illness in a 2011 health assessment of dolphins living in Barataria Bay, Louisiana. NOAA scientists Dr. Rowles and Dr. Lori Schwacke spoke about the results of this health assessment in a 2013 interview:

“One rather unusual condition that we noted in many of the Barataria Bay dolphins was that they had very low levels of some hormones (specifically, cortisol) that are produced by the adrenal gland and are important for a normal stress response.

Under a stressful condition, such as being chased by a predator, the adrenal gland produces cortisol, which then triggers a number of physiological responses including an increased heart rate and increased blood sugar. This gives an animal the energy burst that it needs to respond appropriately.

In the Barataria Bay dolphins, cortisol levels were unusually low. The concern is that their adrenal glands were incapable of producing appropriate levels of cortisol, and this could ultimately lead to a number of complications and in some situations even death.”

Swimming with Pneumonia

Ultrasounds showing a normal dolphin lung, compared to lungs with mild, moderate, and severe lung disease.

Ultrasounds showing a normal dolphin lung, compared to lungs with mild, moderate, and severe lung disease. These conditions are consistent with exposure to oil compounds and were found in bottlenose dolphins living in Barataria Bay, Louisiana, one of the most heavily oiled areas during the Deepwater Horizon oil spill. (NOAA)

In addition to the lesions on adrenal glands, the scientific team discovered that more than one in five dolphins that died within the Deepwater Horizon oil spill footprint had a primary bacterial pneumonia. Many of these cases were unusual in severity, and caused or contributed to death.

Drs. Rowles and Schwacke previously had observed significant problems in the lungs of dolphins living in Barataria Bay. Again, in 2013, they had noted, “In some of the animals, the lung disease was so severe that we considered it life-threatening for that individual.”

In other mammals, exposure to petroleum-based polycyclic aromatic hydrocarbons, known as PAHs, through inhalation or aspiration of oil products can lead to injured lungs and altered immune function, both of which can increase an animal’s susceptibility to primary bacterial pneumonia. Dolphins are particularly susceptible to inhalation effects due to their large lungs, deep breaths, and extended breath hold times.

Learn more about NOAA research documenting the impacts from the Deepwater Horizon oil spill and find more stories reflecting on the five years since this oil spill.


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Five Key Questions NOAA Scientists Ask During Oil Spills

Responders in a small boat pressure-wash rocky shore at the site of an oil spill.

Responders pressure wash the Texas shoreline after the tank ship Eagle Otome oil spill in January of 2010. (NOAA)

During an emergency situation such as an oil spill or ship grounding, scientists in NOAA’s Office of Response and Restoration are guided by five central questions as they develop scientifically based recommendations for the U.S. Coast Guard.

These recommendations help the Coast Guard respond to the incident while minimizing environmental impacts resulting from the spill and response.

Identified in the late 1980s by NOAA, these questions provide a sequential framework for identifying key information at each step that will then inform answers to subsequent questions raised during an oil spill. For example, in order to predict “where could it go?” (question two), you first need to know “what spilled?” (question one), and so on.

Questions guiding NOAA's oil spill response science, with a ship leaking oil, surrounded by boom, with flying birds and a benzene molecule.

Naturally, during a spill response, it may become necessary to revisit earlier questions or assumptions as conditions change and more—or better—information becomes available.

The Scene of the Spill

Establishing what happened is the first step. What is the scenario for this incident and where is it occurring? Gathering this information means figuring out facts such as:

  • the type of incident (e.g., pipeline rupture versus oil tanker collision).
  • the volume and types of oil involved.
  • the incident environment (e.g., stormy, calm).
  • the incident location (e.g., open ocean, near shore, water temperature).

Forecast: Cloudy with a Chance of Oil

Dr. Amy MacFadyen is a NOAA physical oceanographer who frequently works on the next step, which is predicting where the oil is going to go. In most of the spills we respond to, the oil is spilled at or near the water surface and is less dense than water. Initially, the oil will float and form a slick. Dr. MacFadyen looks at what is going on in the environment with wind and waves, which can break up the slick, causing some of the oil to mix into the water column in the form of small droplets.

An important point is that responders can potentially clean up what is on top of the water but recovering oil droplets from the water column is practically impossible. This is why it is so important to spill responders to receive accurate predictions of the movement of the surface slicks so they can quickly implement cleanup or prevention strategies.

In order to make predictions about oil movement, Dr. MacFadyen uses a computer model which includes ocean current and wind forecasts to generate an oil trajectory forecast map. Trajectory forecast models may be updated frequently, as conditions at the site of the spill change. Although the trajectory map shows the position of the oil, there is an element of uncertainty as the forecasts are based on other predictions, such as weather forecasts, which are not always perfect and are themselves subject to change.

To reduce uncertainty, trajectory forecasts incorporate information from trained observers flying over the slick who can confirm the actual location of the oil over the course of the spill response. MacFadyen can then incorporate that updated information as she runs the trajectory forecast model again.

A Sense of Sensitivity

In order to answer what the oil might affect, NOAA developed Environmental Sensitivity Index maps to identify what might be harmed by a spill in different habitat types. It is necessary for responders and decision makers to know what shoreline types exist in the path of the oil, as well as vulnerable species and habitats so that they can plan for the appropriate protection (such as booming) or cleanup method (such as skimming). Cleaning up oil off a sandy beach is very different than a salt marsh, mudflat, or rocky shore.

Animals, plants, and habitats at risk can include those on the water (e.g., seabirds), below the surface (e.g., fish), and on the bottom (e.g., mussels), as well as on the shoreline (e.g., marsh grasses).

Jill Petersen, manager of the Office of Response and Restoration Environmental Sensitivity Index map program, works to ensure that these maps of each U.S. coastal region are up-to-date so that this information is readily available should a spill occur.

Raise the Alarm for Harm

The next step is to look at what harm the oil could cause. When oil is released into the water, it can cause harm to marine animals and the environment. Oil contains thousands of chemical compounds. Polycyclic aromatic hydrocarbons [PDF], or PAHs as they are commonly known, are a class of oil compounds that have been associated with toxic effects in exposed organisms. Because of this, scientists frequently study PAHs in spilled oil to gauge the oil’s potential environmental impact.

However, the complexity of each oil’s chemistry and the changes that occur once it is in the environment make the assessment of risk a challenging task. In order to do so, response biologists consider the type of oil, the sensitivity of potentially exposed organisms, and how the oil is expected to behave in the environment.

Oil spills can involve releases of large volumes of oil that overwhelm whatever natural capacity there might be to absorb impacts, which leads to the photographs we see of heavy oil covering plants and animals. But recent research studies have shown that even minute amounts of petroleum can harm marine eggs and larvae—which means the decisions we make during a response are even more critical to the long-term health of the affected habitats.

NOAA marine biologist Dr. Alan Mearns is an expert on how pollution from oil harms the environment. Each year, he reviews and summarizes recent research in this field to ensure oil spill response recommendations and decisions are based on the most current science that exists.

Sending Help

A skimmer picks up oil off the surface of the Delaware River.

A skimmer picks up oil off the surface of the Delaware River after the tanker Athos spilled oil in 2004. (NOAA)

Answering the previous questions allows us to determining what can be done to help. Doug Helton, the Office of Response and Restoration’s Incident Operations Coordinator, describes possible solutions as usually falling under three categories: containing the source, cleaning up, and protecting the shore.

To contain the source means to limit the further release of pollution by plugging the leak in the pipeline or containing the spill, for example, by keeping the ship from sinking and losing its entire cargo of oil.

Cleanup on the water could be conducted by mechanical means, such as booming and skimming, or through alternative technologies, such as burning the oil in open water or using chemicals to disperse the oil.

Cleanup along the shoreline can be done manually or mechanically using methods such as pressure washing. When considering cleanup options, sometimes monitoring the situation is the best option when a response method could actually cause more harm to the environment. One example is in an oiled marsh because these habitats are especially vulnerable to oil but also to being damaged by people walking through them trying to remove oil.

In addition to providing scientific support to the U.S. Coast Guard, NOAA’s Office of Response and Restoration develops oil spill response software and mapping tools. For responders, NOAA has published a series of job aids and manuals that provide established techniques and guidelines for observing oil, assessing shoreline impact, and evaluating accepted cleanup technologies for a variety of oil spill situations.

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