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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A Major Spill in Tampa Bay—21 Years Ago this Month

Two barges next to one another; one with oil spilled on its deck.

An oil soaked barge, after the 1993 Tampa Bay spill. (NOAA)

 

OR&R’s Doug Helton recalls his experience responding to a major spill in 1993.

August 10 is an anniversary of sorts.  21 years ago, I spent much of the month of August on the beaches of Pinellas County, Florida.  But not fishing and sunbathing. On August 10, 1993, three vessels, the freighter Balsa 37, the barge Ocean 255, and the barge Bouchard 155, collided near the entrance of Tampa Bay, Florida.

A barge on fire, with smoke coming form the deck.

The collision resulted in a fire on one of the barges and caused a major spill. (NOAA)

The collision resulted in a fire on one of the barges and caused a major oil spill. Over 32,000 gallons of jet fuel, diesel, and gasoline and about 330,000 gallons of heavy fuel oil spilled from the barges. Despite emergency cleanup efforts, the oil fouled 13 miles of beaches and caused injury to birds, sea turtles, mangrove habitat, seagrasses, salt marshes, shellfish beds,  as well as closing many of the waterways to fishing and boating.

The prior year I had been hired by NOAA and tasked with developing a Rapid Assessment Program (RAP) to provide a quick response capability for oil and chemical spill damage assessments, focusing on the collection of perishable data and information, photographs, and videotape in a timely manner to determine the need for a natural resource damage assessment. The emergency nature of spills requires that this type of information be collected within hours after the release. Time-sensitive data, photographs, and videotape are often critical when designing future assessment studies and initiating restoration planning—and are also used later as evidence in support of  Natural Resource Damage Assessment (NRDA) claims. The Tampa Bay spill was one of the first major responses for the RAP team.

The case was settled long ago and restoration projects have all been implemented to address the ecological and socioeconomic impacts of the spill. But some of the damage assessment approaches developed during that incident are still used today, and some of the then innovative restoration approaches are now more commonplace.

Sunset behind a bridge over a bay.

Tampa Bay, Skyway Bridge sunset, August 3, 2013. (Jeff Krause/Creative Commons)


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In a Louisiana Marsh, an Uncommon Opportunity to Learn about Burning Oil

This is a post by LTJG Kyle Jellison, NOAA Scientific Support Coordinator.

“Every day is a new adventure.” I came to believe this phrase while sailing on the high seas, but it proves true as a NOAA Scientific Support Coordinator as well. There have been many adventures in my time working in the Gulf of Mexico doing emergency response for oil spills and hazardous materials releases.

The most recent oil spill—a pipeline leak in a Louisiana marsh—didn’t seem out of the ordinary, that is, until the Unified Command in charge of the response turned to alternative approaches to quicken and improve the effectiveness of the cleanup.

The Spill and Our Options

On May 28, 2014 a plane hired by Texas Petroleum Investment Company was performing a routine aerial survey of their inland oilfield and noticed a slight oil sheen and a dead clump of roseau cane (phragmites). This sparked further investigation and the discovery of 100 barrels (4,200 gallons) of crude oil, which had leaked out of a breach in their pipeline passing through the Delta National Wildlife Refuge, outside of Venice, Louisiana. Pipelines like this one are routinely inspected, but as they age the potential for corrosion and spills increases.

Roseau cane is a tall, woody plant, similar to bamboo, reaching heights of up to 20 feet. The stalks grow very close together and in water depths between two and 30 inches. This creates a complex situation which is very hard to clean oil out from.

The least invasive method for oil cleanup is to flush out the oil with high volumes of water at low pressure, but this is a long process with low amounts of oil recovered each day. Another common practice is to flush with water while cutting lanes into the vegetation, creating pathways for the oil to migrate along for recovery. Though more aggressive and with higher amounts of oil recovered each day, it still would likely take many weeks or months to clean up this particular oil spill using this method.

An Unconventional Solution

What about doing a controlled burn of the oil where it is, a strategy known as in situ burning? It removes a large amount of oil in a matter of days, and when performed properly, in situ burning can help marsh vegetation recover in five years or less for more than 75 percent of cases in one study.

In situ burning, Latin for burning in place, is considered an “alternative” response technology, rather than part of the regular suite of cleanup options, and is only employed under the right set of circumstances. More information about this can be found in the NOAA report “Oil Spills in Marshes,” which details research and guidelines for in situ burning in chapter 3, Response.

To help determine if burning was appropriate in this case, the Unified Command brought in the NOAA Scientific Support Team, U.S. Fish and Wildlife Service Fire Management Team, U.S. Coast Guard Gulf Strike Team, and T&T Marine Firefighting and Salvage. After considering the situation, gaining consensus, developing a burn plan, and earning the support of Regional Response Team 6, it was time to light it up!

Where There’s Smoke …

On June 3, 2014, we burned the oil for two hours, with flames reaching 40 feet. The next day, we burned for another six hours. There was a lot of oil to be burned, with pockets of oil spread throughout three acres of impacted marsh. The fire remained contained to the area where enough oil was present to support the burn, extinguishing once it reached the edge of the oiled marsh.

We have an ongoing study to evaluate the impacts of the burn, and preliminary results indicate that there was minimal collateral damage. More than 70 percent of the oil was burned over the two-day period. We considered this to be a very successful controlled burn. The much less remaining oil will be recovered by mechanical methods within a few weeks, instead of months.

Texas Petroleum Investment Company, as the responsible party in this case, will be responsible for all costs incurred for this incident, including cleanup and monitoring (and restoration, if necessary).

To help ensure we learn something from this incident, an assessment team entered the impacted marsh before the burns to collect oil, water, and sediment samples. The team also collected samples after each day of burning and returned a week after the burn to assess the condition of the vegetation and collect samples. This multi-agency team will return to the site in August for more sampling and monitoring.

The long-term monitoring and sampling project is being managed by NOAA, Louisiana Department of Environmental Quality, Fish and Wildlife Service, and Texas Petroleum Investment Company. We are conducting the study under the umbrella of the Response Science and Technology Subcommittee of the New Orleans Area Committee, a standing body of response scientists. Jeff Dauzat of Louisiana Department of Environmental Quality and I co-chair this subcommittee and are looking forward to the results of this ongoing scientific project.

Was burning the right move? The science will speak for itself in time.

For more information:

Man standing in a marsh with smoke in the background.LT Kyle Jellison is a Scientific Support Coordinator for NOAA’s Office of Response and Restoration. He supports Federal On-Scene Coordinators throughout the Gulf of Mexico by providing mission critical scientific information for response and planning to oil and hazardous material releases.


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Marine Life in Gulf of Mexico Faces Multiple Challenges

Editor’s Note: This is a revised posting by Maggie Broadwater of NOAA’s National Centers for Coastal Ocean Science that has corrected some factual misstatements in the original post.

photo of a bottlenose dolphin calf.

A bottlenose dolphin calf in the Gulf of Mexico. (NOAA)

Animals living in coastal waters can face a number of environmental stressors—both from nature and from humans—which, in turn, may have compounding effects. This may be the case for marine life in the Gulf of Mexico which experiences both oil spills and the presence of toxic algae blooms.

On the Lookout

Marine sentinels, like bottlenose dolphins in the Gulf of Mexico, share this coastal environment with humans and consume food from many of the same sources. As marine sentinels, these marine mammals are similar to the proverbial “canary in the coal mine.” Studying bottlenose dolphins may alert us humans to the presence of chemical pollutants, pathogens, and toxins from algae (simple ocean plants) that may be in Gulf waters.

Texas Gulf waters, for an example, are a haven for a diverse array of harmful algae. Additional environmental threats for this area include oil spills, stormwater and agricultural runoff, and industrial pollution.

Recently, we have been learning about the potential effects of oil on bottlenose dolphin populations in the Gulf of Mexico as a result of the Deepwater Horizon oil spill in April 2010. Dolphins with exposure to oil may develop lung disease and adrenal impacts, and be less able to deal with stress.

Certain types of algae produce toxins that can harm fish, mammals, and birds and cause illness in humans. During harmful algal blooms, which occur when colonies of algae “bloom” or grow out of control, the high toxin levels observed often result in illness or death for some marine life, and low-level exposure may compromise their health and increase their susceptibility to other stressors.

However, we know very little about the combined effects from both oil and harmful algal blooms.

A barge loaded with marine fuel oil sits partially submerged in the Houston Ship Channel, March 22, 2014. The bulk carrier Summer Wind, reported a collision between the Summer Wind and a barge, containing 924,000 gallons of fuel oil, towed by the motor vessel Miss Susan. (U.S. Coast Guard)

A barge loaded with marine fuel oil sits partially submerged in the Houston Ship Channel, March 22, 2014. The bulk carrier Summer Wind, reported a collision between the Summer Wind and a barge, containing 924,000 gallons of fuel oil, towed by the motor vessel Miss Susan. (U.S. Coast Guard)

Familiar Waters

Prior to the Galveston Bay oil spill, Texas officials closed Galveston Bay to the harvesting of oysters, clams, and mussels on March 14, 2014 after detecting elevated levels of Dinophysis. These harmful algae can produce toxins that result in diarrhetic shellfish poisoning when people eat contaminated shellfish. Four days later, on March 18, trained volunteers from NOAA’s Phytoplankton Monitoring Network detected Pseudo-nitzschia in Galveston Bay. NOAA Harmful Algal Bloom scientist Steve Morton, Ph.D., confirmed the presence of Pseudo-nitzchia multiseries, a type of algae known as a diatom that produces a potent neurotoxin affecting humans, birds, and marine mammals. NOAA’s Harmful Algal Bloom Analytical Response Team confirmed the toxin was present and notified Texas officials.

When Oil and Algae Mix

Studying marine mammal strandings and deaths helps NOAA scientists and coastal managers understand the effects of harmful algal blooms across seasons, years, and geographical regions. We know that acute exposure to algal toxins through diet can cause death in marine mammals, and that even exposures to these toxins that don’t kill the animal may result in serious long-term effects, including chronic epilepsy, heart disease, and reproductive failure.

But in many cases, we are still working to figure out which level of exposure to these toxins makes an animal ill and which leads to death. We also don’t yet know the effects of long-term low-level toxin exposure, exposure to multiple toxins at the same time, or repeated exposure to the same or multiple toxins. Current NOAA research is addressing many of these questions.

A dolphin mortality event may have many contributing factors; harmful algae may only be one piece in the puzzle. Thus, we do not yet know what effects recent Dinophysis and Pseudo-nitzchia blooms may have on the current marine mammal populations living in Texas coastal waters. Coastal managers and researchers are on alert for marine mammal strandings that may be associated with exposure to harmful algae, but the story is unfolding, and is very complex.

Photo of volunteer with a microscope.

Galveston volunteer with NOAA’s Phytoplankton Monitoring Network helps identify toxic algae. (NOAA)

On March 22, 2014, four days after harmful algae were found in Galveston Bay, the M/V Summer Wind collided with oil tank-barge Kirby 27706 in Galveston Bay near Texas City, releasing approximately 168,000 gallons of thick, sticky fuel oil. The Port of Houston was closed until March 27. State and federal agencies are responding via the Unified Command. NOAA is providing scientific support and Natural Resource Damage Assessment personnel are working to identify injured natural resources and restoration needs. Much of the oil has come ashore and survey teams are evaluating the shorelines to make cleanup recommendations.

Time will tell if the harmful algal toxins and oil in Galveston Bay have a major negative effect on the marine mammals, fish, and sea turtles that live in surrounding waters. Fortunately, NOAA scientists with a range of expertise—from dolphins to harmful algae to oil spills—are on the job.

Maggie BroadwaterMaggie Broadwater is a Research Chemist and serves as coordinator for NOAA’s Harmful Algal Bloom Analytical Response Team at the National Centers for Coastal Ocean Science in Charleston, S.C.  Dr. Broadwater earned a Ph.D. in Biochemistry from the Medical University of South Carolina in 2012 and has a M.S. in Biomedical Sciences and a B.S. in Biochemistry.


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Texas City “Y” Incident: Aftermath of the Oil Spill in Galveston Bay, Texas

photo of people cleaning up contaminated sand.

Task force members remove oil-contaminated sand from the beach on Matagorda Island, Texas, March 30, 2014. Cleanup operations are being directed by a unified command comprised of personnel from the Texas General Land Office, U.S. Coast Guard and Kirby Inland marine. (U.S. Coast Guard)

The March 22, 2014 vessel collision in Galveston Bay (see Kirby Barge Oil Spill, Houston/Texas City Ship Channel) resulted in an oil spill of approximately 168,000 gallons.

Although scattered and trace amounts of oil were found as far west as Mustang and Padre Islands, almost all of the oil is still thought to be stranded on shorelines between Galveston and Matagorda.  Some widely scattered floating tarballs and sheens may be possible, but no floating oil was observed on overflights today.

As of Monday, March 31, NOAA National Marine Fisheries Service teams report 21 dolphins and 4 turtles stranded. Most of these are in the Galveston area but reports from Matagorda Island are increasing.  All of the dolphins were dead, two turtles were captured alive and are being rehabilitated.  Most of the animals were not visibly oiled but necropsies are still underway.  Approximately 150 dead birds have been reported in the Galveston area and 30 in the Matagorda area.

Cleanup activities in the Galveston area are proceeding and the U.S. Coast Guard is beginning the process to downsize staffing and phase out response efforts.

Photo of two people locating oil on beach.

Two members of the Shoreline Assessment Team locate oiled impact points on Matagorda Island, March 29, 2014. The Unified Command in Port O’Connor is overcoming logistical challenges posed by the remote island in order to clean up the migrating oil from the Texas City collision. (U.S. Coast Guard)

Surveying Oiled Shorelines

After an oil spill like this one happens along the coast, spill responders need to figure out and document where oil has come ashore, what habitats have been affected, and how to clean up the shoreline.

NOAA helped develop a systematic method for surveying an affected shoreline after an oil spill. This method, known as Shoreline Cleanup and Assessment Technique (SCAT), is designed to support decision-making for shoreline cleanup. We have SCAT experts helping coordinate these shoreline surveying efforts for the oiled beaches in Texas.

In general, SCAT surveys begin early in the response to assess initial shoreline conditions (including even before oil comes ashore, as a reference) and ideally continue to work in advance of cleanup.

Surveys continue during the response to verify shoreline oiling, cleanup effectiveness, and eventually, to conduct final evaluations of shorelines to ensure they meet standards for ending cleanup.

SCAT teams include people trained in the techniques, procedures, and terminology of shoreline assessment. Members of a SCAT team may come from federal agencies (usually from the NOAA Scientific Support Team or U.S. Coast Guard), state agencies, a representative of the organization responsible for the spill, and possibly the landowner or other local stakeholders.

While out walking the shoreline, SCAT team members prepare field maps and forms detailing the area surveyed and make specific cleanup recommendations. Later, they go back to the areas surveyed to verify cleanup effectiveness, modifying guidelines as needed if conditions change.

The data they collect informs a shoreline cleanup plan that maximizes the recovery of oiled habitats and resources, while minimizing the risk of injury from cleanup efforts. This means, for example, determining whether active cleanup is necessary or whether certain limitations on cleanup are needed to protect ecological, economic, or cultural concerns.


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Progress at the Texas City “Y” Oil Spill in Galveston Bay

Photo of workers assessing shoreline.

Federal and local agency workers help clean up the beaches affected by oil spill on March 27, 2014. Cleanup efforts continue for the Texas City “Y” response, which resulted from a collision between a bulk carrier and a barge Saturday in the Houston Ship Channel. (U.S. Coast Guard)

POSTED: March 28, 2014 | UPDATED: March 30, 2014 –The March 22 vessel collision in Galveston Bay (see Kirby Barge Oil Spill, Houston/Texas City Ship Channel, Port Bolivar, Texas) that resulted in an oil spill of approximately 168,000 gallons caused the closure of the heavily trafficked Port of Houston for 3 days. Some oil came ashore near the collision site in the Galveston area, but northeasterly winds carried the remainder out of the Bay. Longshore currents then carried the oil to the west, some as far as 150 miles, were it stranded on Matagorda Island. A small fraction of the oil is still afloat off Mustang and Padre Islands.

Photo of a woman and a moan looking at paperwork on the beach.

Volunteers assess a three-mile stretch of shoreline at Stewart Beach in Galveston, Texas, on March 28, 2014. Workers and volunteers have been working Galveston shoreline in response to the Texas City oil spill. (U.S. Coast Guard)

Although most all of the oil is still thought to be stranded on shorelines between Galveston and Matagorda, overflights this morning noted sheens and tarballs further west than anticipated, near Aransas Pass. This oil could impact Mustang and Padre Islands and the need for additional trajectory forecasts is being reconsidered. Overflight observers also noted that shoreline oil on Matagorda Island is rapidly being buried under clean sand. Burial of oil is common on active shorelines, but increases the complexity of the response, especially in areas where mechanical cleanup methods are not feasible or inappropriate because of their environmental sensitivity.

NOAA is providing scientific support to the U.S. Coast Guard, including science coordination, trajectories, shoreline assessment, information management and common operational picture, overflight, weather, resources at risk, seafood safety, and marine mammal and turtle stranding personnel. The NOAA Weather Service Incident Meteorologist is on-scene.

See March 27 U.S. Coast Guard news release.


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Latest Research Finds Serious Heart Troubles When Oil and Young Tuna Mix

Atlantic bluefin tuna prepares to eat a smaller fish.

Atlantic bluefin tuna are a very ecologically and economically valuable species. However, populations in the Gulf of Mexico are at historically low levels. (Copyright: Gilbert Van Ryckevorsel/TAG A Giant)

In May of 2010, when the Deepwater Horizon rig was drilling for oil in the open waters of the Gulf of Mexico, schools of tuna and other large fish would have been moving into the northern Gulf. This is where, each spring and summer, they lay delicate, transparent eggs that float and hatch near the ocean surface. After the oil well suffered a catastrophic blowout and released 4.9 million barrels of oil, these fish eggs may have been exposed to the huge slicks of oil floating up through the same warm waters.

An international team of researchers from NOAA, Stanford University, the University of Miami, and Australia recently published a study in the journal Proceedings of the National Academy of Sciences exploring what happens when tuna mix with oil early in life.

“What we’re interested in is how the Deepwater Horizon accident in the Gulf of Mexico would have impacted open-ocean fishes that spawn in this region, such as tunas, marlins, and swordfishes,” said Stanford University scientist Barbara Block.

This study is part of ongoing research to determine how the waters, lands, and life of the Gulf of Mexico were harmed by the Deepwater Horizon oil spill and response. It also builds on decades of research examining the impacts of crude oil on fish, first pioneered after the 1989 Exxon Valdez oil spill in Alaska. Based on those studies, NOAA and the rest of the research team knew that crude oil was toxic to young fish and taught them to look carefully at their developing hearts.

“One of the most important findings was the discovery that the developing fish heart is very sensitive to certain chemicals derived from crude oil,” said Nat Scholz of NOAA’s Northwest Fisheries Science Center.

This is why in this latest study they examined oil’s impacts on young bluefin tuna, yellowfin tuna, and amberjack, all large fish that hunt at the top of the food chain and reproduce in the warm waters of the open ocean. The researchers exposed fertilized fish eggs to small droplets of crude oil collected from the surface and the wellhead from the Deepwater Horizon spill, using concentrations comparable to those during the spill. Next, they put the transparent eggs and young fish under the microscope to observe the oil’s impacts at different stages of development. Using a technology similar to doing ultrasounds on humans, the researchers were able create a digital record of the fishes’ beating hearts.

All three species of fish showed dramatic effects from the oil, regardless of how weathered (broken down) it was. Severely malformed and malfunctioning hearts was the most severe impact. Depending on the oil concentration, the developing fish had slow and irregular heartbeats and excess fluid around the heart. Other serious effects, including spine, eye, and jaw deformities, were a result of this heart failure.

Top: A normal young yellowfin tuna. Bottom: A deformed yellowfin tuna exposed to oil during development.

A normal yellowfin tuna larva not long after hatching (top), and a larva exposed to Deepwater Horizon crude oil as it developed in the egg (bottom). The oil-exposed larva shows a suite of abnormalities including excess fluid building up around the heart due to heart failure and poor growth of fins and eyes. (NOAA)

“Crude oil shuts down key cellular processes in fish heart cells that regulate beat-to-beat function,” noted Block, referencing another study by this team.

As the oil concentration, particularly the levels of polycyclic aromatic hydrocarbons (PAHs), went up, so did the severity of the effects on the fish. Severely affected fish with heart defects are unlikely to survive. Others looked normal on the outside but had underlying issues like irregular heartbeats. This could mean that while some fish survived directly swimming through oil, heart conditions could follow them through life, impairing their (very important) swimming ability and perhaps leading to an earlier-than-natural death.

“The heart is one of the first organs to appear, and it starts beating before it’s completely built,” said NOAA Fisheries biologist John Incardona. “Anything that alters heart rhythm during embryonic development will likely impact the final shape of the heart and the ability of the adult fish to survive in the wild.”

Even at low levels, oil can have severe effects on young fish, not only in the short-term but throughout the course of their lives. These subtle but serious impacts are a lesson still obvious in the recovery of marine animals and habitats still happening 25 years after the Exxon Valdez oil spill.


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Study Shows Gulf Dolphins in Poor Health following Deepwater Horizon Oil Spill

A dolphin is observed with oil on its skin on August 5, 2010, in Barataria Bay, La.

A dolphin is observed with oil on its skin on August 5, 2010, in Barataria Bay, La. (Louisiana Department of Wildlife and Fisheries/Mandy Tumlin)

Barataria Bay, located in the northern Gulf of Mexico, received heavy and prolonged oiling after the 2010 Deepwater Horizon oil spill. This area is also home to many bottlenose dolphins. In the wake of the spill, how healthy are dolphins living in this area? And how do they compare to dolphins living elsewhere?

As part of the Natural Resource Damage Assessment for the Deepwater Horizon oil spill, a team of more than 50 government, academic, and non-governmental researchers assessed the health of bottlenose dolphins living in Louisiana’s Barataria Bay, which received heavy oiling following the Deepwater Horizon spill, and in Florida’s Sarasota Bay, which was not oiled following the spill.

The team of scientists and veterinarians temporarily captured live dolphins, performed comprehensive health examinations on them at the site, and then released them. The health exam included measuring each dolphin’s length and weight; doing a physical exam; sampling skin, blood, and blubber; and performing an ultrasound to evaluate their internal organs, particularly their lung condition and pregnancy status. The team has published the results of this study in the peer-reviewed journal Environmental Science & Technology.

We spoke with two of the NOAA scientists involved, Dr. Lori Schwacke and Dr. Teri Rowles, to learn more about the research and what their findings mean for dolphins in the Gulf of Mexico.

Q: When did you conduct the dolphin health assessments and what did you observe?

Aug 2011: A veterinarian performs an ultrasound to assess a Barataria Bay dolphin’s health.

Aug 2011: A veterinarian performs an ultrasound to assess a Barataria Bay dolphin’s health. (NOAA)

The first health assessments were conducted in the summer of 2011 in Barataria Bay, La., and in Sarasota Bay, Fla. We found that the dolphins in Barataria Bay were in very poor health. Many of them were underweight and their blood tests showed a number of abnormal conditions such as anemia, elevated markers of inflammation, and increased liver enzymes.

Also, 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.

We also found significant lung disease. We looked for several different abnormalities based on studies that have been done on captive animals, and what we saw was most consistent with pneumonia. In some of the animals, the lung disease was so severe that we considered it life-threatening for that individual.

Q: How serious were the conditions observed in dolphins from Barataria Bay?

Some of the conditions observed in these dolphins were very serious. Some of the animals had multiple health issues going on, such as lung disease, very high liver enzymes, and indications of chronic inflammation. The veterinarians assigned a prognosis for each animal and nearly half of the Barataria Bay dolphins were given a guarded (uncertain outcome) or worse prognosis. In fact, 17 percent of them were given a poor or grave prognosis, indicating that they weren’t expected to live.

In comparison, in Sarasota we had only one guarded prognosis and the rest were in good or fair condition. Sarasota dolphins were much healthier than Barataria Bay dolphins.

Q: Have you been able to follow up on the status of any of the dolphins examined during these assessments?

We know one of them died. Y12 was a 16-year-old male that we examined in August 2011. He was underweight and many of his blood parameters were out of the expected range. The veterinary team assigned him a grave prognosis. His carcass was recovered by the Louisiana Department of Wildlife and Fisheries in January of 2012. So we know that he only survived a little over five months  after the health assessment was conducted. . But often carcasses aren’t recovered, and there were other dolphins that we examined that we didn’t expect to live for very long.

We’re also conducting photographic monitoring studies to monitor the survival and reproductive success or failure of the dolphins we sampled. Several of the females we sampled in Barataria Bay were pregnant so we’ve been monitoring them around and past their due date to see whether or not we see them with a calf. The gestation period for a dolphin is around 12 months, so these monitoring studies take a little bit longer. We hope to report those results soon.

Q: Are the disease conditions observed in Barataria Bay dolphins—lung disease, compromised stress hormone response—consistent with those expected from exposure to oil?

The decreased cortisol response is something fairly unusual but has been reported from experimental studies of mink exposed to fuel oil. The respiratory issues are also consistent with experimental studies in animals and clinical reports of people exposed to petroleum hydrocarbons.

Q: How do you know these health impacts weren’t caused by other lingering pollutants in the Gulf?

We analyzed the dolphins’ blubber to evaluate the levels of contaminants that have been previously reported in marine mammal tissues and then also linked with health effects. This covered a fairly broad suite of contaminants and included polychlorinated biphenyls (PCBs) as well as a suite of persistent pesticides that we know accumulate in dolphins over their lifetime, leaving a record of their exposure. We found that the levels of these pollutants in Barataria Bay dolphins were actually lower than the levels in Sarasota Bay dolphins. The levels from Barataria Bay dolphins were also low compared to previously reported levels in dolphins from a number of other coastal sites in the southeastern U.S. Therefore, we don’t think that the health effects we saw can be attributed to these other pollutants that we looked at.

Q: Are there more dolphin health assessments currently taking place or planned for the future?

Yes, in the summer of 2013 we repeated the studies in Sarasota Bay and Barataria Bay and expanded the studies to Mississippi Sound, where we assessed dolphins both in Mississippi and in Alabama waters. Those samples and data are still being analyzed.

Q: Was there anything about this study that you found surprising?

The magnitude of the health effects that we saw was surprising. We’ve done these health assessments in a number of locations across the southeast U.S. coast and we’ve never seen animals that were in this poor of condition.

Q: How does this study relate to or inform the investigation of the high number of marine mammal strandings observed along the Gulf Coast since February 2010 (the Unusual Mortality Event), which pre-dates the Deepwater Horizon oil spill?

Following the Deepwater Horizon oil spill, numerous dolphins were documented encountering oil, such as those in this photo from July 2010.

Following the Deepwater Horizon oil spill, numerous dolphins were documented encountering oil, such as those in this photo from July 2010. (NOAA)

The Unusual Mortality Event that’s underway is in the same general geographic area as the Deepwater Horizon oil spill response and overlaps with the Natural Resource Damage Assessment. These findings overlap with the high number of strandings, particularly in the Barataria Bay or central Louisiana area.

When you have a significant event like an oil spill or an Unusual Mortality Event, being able to study both live and dead animals provides more information about what might be going on as animals get ill and then die. Having access to findings from both of these studies enables us to look for commonalities between what we’re finding in the sick animals and what we’re finding in the dead animals to better evaluate causes and contributing factors.

Q: Outside of NOAA, who else did you work with to perform the health assessment?

This work was part of the Deepwater Horizon Natural Resource Damage Assessment being conducted cooperatively among NOAA, other federal and state trustees, and BP. This wouldn’t have been possible without the help of a number of our partners, including the National Marine Mammal Foundation, Chicago Zoological Society, and Louisiana Department of Wildlife and Fisheries. Also, Seaworld and the Georgia Aquarium provided personnel to support our studies. Their expertise and experience were key to getting these studies done.

We greatly appreciate the efforts of researchers from the Sarasota Dolphin Research Program, which led the dolphin health assessments in Sarasota.

Watch a video of the researchers as they temporarily catch and give health exams to some of the dolphins in Barataria Bay, La., in August of 2011:

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