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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Creative Solutions Save Money and Marsh Along Galveston Bay, Texas

Hazardous waste sites create a cascade of impacts that affect the health of communities, water quality, and the local environment. That’s why the long-term cleanup and restoration of these sites often requires a coordinated—and creative—regional approach.

This was certainly the case for the Malone Services Company hazardous waste site in Texas City, Texas. By combining efforts and funding in unexpected ways, federal, state and local partners came up with the most effective restoration solutions for the area, saving time and money along the way.

A Hazardous History

Located on the shores of Swan Lake and Galveston Bay, the 150-acre Malone facility produced decades of pollution affecting both groundwater within the site and runoff into nearby surface waters, creating long-term contamination problems for the region. Hundreds of businesses sent more than 480 million gallons of waste to the Malone facility for reclamation, storage, and disposal. During its operation from 1964 to 1997, waste products from those industries included acids, contaminated residues, solvents, and waste oils.

Designated a Superfund site in 2001, state and federal agencies collaborated early on during the cleanup, investigating the extent of the contamination, assessing which natural resources were affected, and planning restoration solutions to make up for these impacts. By sharing information they all needed, the agencies avoided additional costs from performing independent studies.

Aerial view of Malone Services Company waste site next to wetlands and Galveston Bay.

An aerial view of the Malone Services Company hazardous waste site shows the proximity of wetlands and Galveston Bay. (Department of the Interior)

Officially called “trustees,” the state and federal agencies involved included the Texas Commission on Environmental Quality, the Texas Parks and Wildlife Department, the Texas General Land Office, NOAA, and the U.S. Fish and Wildlife Service. Working together, the trustees carried out the Natural Resources Damage Assessment process for the Malone waste site. In 2012, they reached a settlement with the responsible parties for approximately $3.1 million. In the settlement, the trustees determined that Malone’s pollution had significant negative impacts on natural resources, affecting upland-woodland, freshwater marsh, and saltwater marsh habitat around the Malone site.

To restore those natural resources, the trustees finalized the damage assessment and restoration plan [PDF] in 2015.  Key elements of the plan center on restoring nearby natural areas, including freshwater wetlands in Campbell Bayou, terrestrial woodlands in the Virginia Peninsula Preserve, and intertidal saltwater wetlands in Pierce Marsh.

Creative Restoration at Pierce Marsh

Situated on the north shore of West Galveston Bay, not far from the Malone site, Pierce Marsh covers more than 2,300 acres, supports vibrant seasonal and year-round bird and fish populations, and is home to commercial and recreational fisheries. It is also located near vital, colonial water bird nesting islands and serves as an important feeding area during the nesting season.

However, the marsh became completely flooded by the 1990s, compromising its habitat quality as the ground beneath it sank due to subsidence. “Pierce Marsh has experienced one of the greatest rates of wetland loss in Galveston Bay and the restoration of its fish and wildlife habitat is recognized as a regional restoration priority,” noted Jamie Schubert, NOAA Restoration Center Marine Habitat Specialist. The Galveston Bay Foundation, a co-owner of the land, has spent the last 15 years methodically restoring the marsh.

Money from the Malone settlement is funding the restoration of 70 acres of wetland at Pierce Marsh. Having each federal and state agency contribute to a portion of the success—through the funding, planning, engineering, design, permitting, implementation, or monitoring—this restoration project has saved time and money.

Birds swoop over a pipeline releasing mud into a marsh.

Sediments pouring from the end of a long pipeline are raising the ground elevation of Pierce Marsh, improving habitat for birds and fish and helping make up for the loss of similar habitat due to pollution at the Malone waste site. (Credit: John Morris/Mike Hooks, Inc.)

One cost-saving example came out of NOAA habitat conservation experts and U.S. Army Corps of Engineers project manager, Seth Jones, both serving on an Interagency Coordination Team for the Texas Gulf Intracoastal Waterway. The Corps maintains the waterway, dredging it deep and wide enough to meet current shipping demands. Out of those meetings emerged the idea to “beneficially” use the sediments from the waterway dredging to raise the ground level of Pierce Marsh.

“Our project delivery team included NOAA, the Galveston Bay Foundation, Texas Parks and Wildlife, U.S. Fish and Wildlife Service, the Texas General Land Office, and the Texas Department of Transportation,” said Jones. “It was because of their instrumental input throughout the design phase that we are going to get a good start on the Galveston Bay Foundation’s long-term marsh restoration plan at Pierce Marsh complex.”

To pay for transportation of the dredged sediments to restore the marsh, the Texas trustees recommended that combined settlement funds from the Malone Services Company site, the Tex Tin hazardous waste site (also in the area), and another Texas state pollution case could help fund the needed restoration, yielding more restoration for their dollars.

“This beneficial use project has multiple benefits—it keeps the dredged material away from existing seagrass areas in West Bay and helps restore lost wetland habitat that has disappeared over the last fifty years in this area,” said Bob Stokes, President of Galveston Bay Foundation.

A Restoration Recipe for Success

Small levee of sediment and grass in a marsh.

A small levee constructed in Pierce Marsh, near Galveston Bay, Texas, contains dredged sediments that will restore marsh elevation and improve habitat quality. (NOAA)

Members of the trustee council have expressed enthusiasm for the project as well. “The U.S. Fish and Wildlife Service is excited to be part of the Pierce Marsh restoration project, which will restore estuary marsh habitat and benefit migratory birds and waterfowl,” said Benjamin Tuggle, Southwest Regional Director, U.S. Fish and Wildlife Service. “Multiple state, federal, and NGO partners have come together to restore contaminated areas at the Malone site.”

The Texas trustees anticipate building upon these efforts and using this approach to continue restoring coastal marshes, making ongoing monitoring of the project very important. They have partnered with Galveston Bay Foundation and Ducks Unlimited to monitor sediment settlement rates, which are used to assess project success and inform future projects.

“The Pierce Marsh reclamation project will make a significant contribution to restoring the coastal wetlands and natural resources that have been lost over time in this part of West Galveston Bay,” according to Richard Seiler, Program Manager of the Texas Commission on Environmental Quality Natural Resource Trustee Program. “The project represents a true team effort between the Texas Commission on Environmental Quality and the other state and federal natural resource trustees, the U.S. Army Corps of Engineers, and our NGO partners, the Galveston Bay Foundation and Ducks Unlimited.”

The restoration of Pierce Marsh is a success story of interagency cooperation and partner coordination. Federal and state agencies and non-profit organizations with differing missions came together on a project that would benefit everyone involved. Working together to share financial and technical resources, ultimately enabled them to use sediment historically viewed as waste material to restore vital coastal habitat, enhancing the area for wildlife and fisheries for generations to come.


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NOAA Scientist Helps Make Mapping Vital Seagrass Habitat Easier and More Accurate

Shoal grass seagrass on a sandy ocean floor.

Seagrass beds serve as important habitat for a variety of marine life, and understanding their growth patterns better can help fisheries management and restoration efforts. (NOAA)

Amy Uhrin was sensing a challenge ahead of her. As a NOAA scientist working on her PhD, she was studying the way seagrasses grow in different patterns along the coast, and she knew that these underwater plants don’t always create lush, unbroken lawns beneath the water’s surface.

Where she was working, off the North Carolina coast near the Outer Banks, things like the churning motion of waves and the speed of tides can cause seagrass beds to grow in patchy formations. Clusters of bigger patches of seagrass here, some clusters of smaller patches over there. Round patches here, elongated patches over there.

Uhrin wanted to be able to look at aerial images showing large swaths of seagrass habitat and measure how much was actually seagrass, rather than bare sand on the bottom of the estuary. Unfortunately, traditional methods for doing this were tedious and tended to produce rather rough estimates. These involved viewing high-resolution aerial photographs, taken from fixed-wing planes, on a computer monitor and having a person digitally draw lines around the approximate edges of seagrass beds.

While that can be fairly accurate for continuous seagrass beds, it becomes more problematic for areas with lots of small patches of seagrass included inside a single boundary. For the patchy seagrass beds Uhrin was interested in, these visual methods tended to overestimate the actual area of seagrass by 70% to more than 1,500%. There had to be a better way.

Seeing the Light

Patches of seagrass beds of different sizes visible from the air.

Due to local environmental conditions, some coastal areas are more likely to produce patchy patterns in seagrass, rather than large beds with continuous cover. (NOAA)

At the time, Uhrin was taking a class on remote sensing technology, which uses airborne—or, in the case of satellites, space-borne—sensors to gather information about the Earth’s surface (including information about oil spills). She knew that the imagery gathered from satellites (i.e. Landsat) is usually not at a fine enough resolution to view the details of the seagrass beds she was studying. Each pixel on Landsat images is 30 meters by 30 meters, while the aerial photography gathered from low-flying planes often delivered resolution of less than a meter (a little over three feet).

Uhrin wondered if she could apply to the aerial photographs some of the semi-automated classification tools from imagery visualization and analysis programs which are typically used with satellite imagery. She decided to give it a try.

First, she obtained aerial photographs taken of six sites in the shallow coastal waters of North Carolina’s Albemarle-Pamlico Estuary System. Using a GIS program, she drew boundaries (called “polygons”) around groups of seagrass patches to the best of her ability but in the usual fashion, which includes a lot of unvegetated seabed interspersed among seagrass patches.

Six aerial photographs of seagrass habitat off the North Carolina coast, with yellow boundary lines drawn around general areas of seagrass habitat.

Aerial photographs show varying patterns of seagrass growth at six study sites off the North Carolina coast. The yellow line shows the digitally drawn boundaries around seagrass and how much of that area is unvegetated for patchy seagrass habitat. (North Carolina Department of Transportation)

Next, Uhrin isolated those polygons of seagrass beds and deleted everything else in each image except the polygon. This created a smaller, easier-to-scan area for the imagery visualization program to analyze. Then, she “trained” the program to recognize what was seagrass vs. sand, based on spectral information available in the aerial photographs.

Though limited compared to what is available from satellite sensors, aerial photographs contain red, blue, and green wavelengths of light in the visible spectrum. Because plants absorb red and blue light and reflect green light (giving them their characteristic green appearance), Uhrin could train the computer program to classify as seagrass the patches where green light was reflected.

Classify in the Sky

Amy Uhrin stands in shallow water documenting data about seagrass inside a square frame of PVC pipe.

NOAA scientist Amy Uhrin found a more accurate and efficient approach to measuring how much area was actually seagrass, rather than bare sand, in aerial images of coastal North Carolina. (NOAA)

To Uhrin’s excitement, the technique worked well, allowing her to accurately identify and map smaller patches of seagrass and export those maps to another computer program where she could precisely measure the distance between patches and determine the size, number, and orientation of seagrass patches in a given area.

“This now allows you to calculate how much of the polygon is actually seagrass vegetation,” said Uhrin, “which is good for fisheries management.” The young of many commercially important species, such as blue crabs, clams, and flounder, live in seagrass beds and actively use the plants. Young scallops, for example, cling to the blades of seagrass before sliding off and burrowing into the sediment as adults.

In addition, being able to better characterize the patterns of seagrass habitat could come in handy during coastal restoration planning and assessment. Due to local environmental conditions, some areas are more likely to produce patchy patterns in seagrass. As a result, efforts to restore seagrass habitat should aim for restoring not just cover but also the original spatial arrangement of the beds.

And, as Uhrin noted, having this information can “help address seagrass resilience in future climate change scenarios and altered hurricane regimes, as patchy seagrass areas are known to be more susceptible to storms than continuous meadows.”

The results of this study, which was done in concert with a colleague at the University of Wisconsin-Madison, have been published in the journal Estuarine, Coastal and Shelf Science.


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What Happens When Oil Spills Meet Massive Islands of Seaweed?

Floating bits of brown seaweed at ocean surface

Floating rafts of sargassum, a large brown seaweed, can stretch for miles across the ocean. (Credit: Sean Nash/Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Generic license)

The young loggerhead sea turtle, its ridged shell only a few inches across, is perched calmly among the floating islands of large brown seaweed, known as sargassum. Casually, it nibbles on the leaf-like blades of the seaweed, startling a nearby crab. Open ocean stretches for miles around these large free-floating seaweed mats where myriad creatures make their home.

Suddenly, a shadow passes overhead. A hungry seabird?

Taking no chances, the small sea turtle dips beneath the ocean surface. It dives through the yellow-brown sargassum with its tangle of branches and bladders filled with air, keeping everything afloat.

Home Sweet Sargassum

This little turtle isn’t alone in seeking safety and food in these buoyant mazes of seaweed. Perhaps nowhere is this more obvious than a dynamic stretch of the Atlantic Ocean off the East Coast of North America named for this seaweed: the Sargasso Sea. Sargassum is also an important part of the Gulf of Mexico, which contains the second most productive sargassum ecosystem in the world.

Some shrimp, crabs, and fish are specially suited to life in sargassum. Certain species of eel, fish, and shark spawn there. Each year, humpback whales, tuna, and seabirds migrate across these fruitful waters, taking advantage of the gathering of life that occurs where ocean currents converge.

Cutaway graphic of ocean with healthy sargassum seaweed habitat supporting marine life.

Illustration of sargassum and associated marine life, including fish, sea turtles, birds, and marine mammals. Sargassum is a brown algae that forms a unique and highly productive floating ecosystem on the surface of the open ocean. (NOAA) Click to enlarge.

The Wide and Oily Sargasso Sea

However, an abundance of marine life isn’t the only other thing that can accumulate with these large patches of sargassum. Spilled oil, carried by currents, can also end up swirling among the seaweed.

If an oil spill made its way somewhere like the Sargasso Sea, a young sea turtle would encounter a much different scene. As the ocean currents brought the spill into contact with sargassum, oil would coat those same snarled branches and bladders of the seaweed. The turtles and other marine life living within and near the oiled sargassum would come into contact with the oil too, as they dove, swam, and rested among the floating mats.

That oil can be inhaled as vapors, be swallowed or consumed with food, and foul feathers, skin, scales, shell, and fur, which in turn smothers, suffocates, or strips the animal of its ability to stay insulated. The effects can be toxic and deadly.

Cutaway graphic of ocean with potential impacts of oil on sargassum seaweed habitat and marine life.

Illustration of the potential impacts of an oil spill on sargassum and associated marine life in the water column. (NOAA) Click to enlarge.

While sea turtles, for example, as cold-blooded reptiles, may enjoy the relatively warmer waters of sargassum islands, a hot sun beating down on an oiled ocean surface can raise water temperatures to extreme levels. What starts as soothing can soon become stressful.

Depending on how much oil arrived, the sargassum would grow less, or not at all, or even die. These floating seaweed oases begin shrinking. Where will young sea turtles take cover as they cross the unforgiving open ocean?

As life in the sargassum starts to perish, it may drop to the ocean bottom, potentially bringing oil and the toxic effects with it. Microbes in the water may munch on the oil and decompose the dead marine life, but this can lead to ocean oxygen dropping to critical levels and causing further harm in the area.

From Pollution to Protection

Young sea turtles swims through floating seaweed mats.

The floating habitat that sargassum creates provides food, refuge, and breeding grounds for an array of marine species, including sea turtles. (NOAA)

NOAA and the U.S. Fish and Wildlife Service have designated sargassum as a critical habitat for threatened loggerhead sea turtles.

Sargassum has also been designated as Essential Fish Habitat by Gulf of Mexico Fishery Management Council and National Marine Fisheries Service since it also provides nursery habitat for many important fishery species (e.g., dolphinfish, triggerfishes, tripletail, billfishes, tunas, and amberjacks) and for ecologically important forage fish species (e.g., butterfishes and flyingfishes).

Sargassum and its inhabitants are particularly vulnerable to threats such as oil spills and marine debris due to the fact that ocean currents naturally tend to concentrate all of these things together in the same places. In turn, this concentrating effect can lead to marine life being exposed to oil and other pollutants for more extended periods of time and perhaps greater impacts.

However, protecting sargassum habitat isn’t impossible and it isn’t out of reach for most people. Some of the same things you might do to lower your impact on the planet—using less plastic, reducing your demand for oil, properly disposing of trash, discussing these issues with elected officials—can lead to fewer oil spills and less trash turning these magnificent islands of sargassum into floating islands of pollution.

And maybe protect a baby sea turtle or two along the way.


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10 Years after Being Hit by Hurricane Katrina, Seeing an Oiled Marsh at the Center of an Experiment in Oil Cleanup

This is a post by Vicki Loe and Amy Merten of NOAA’s Office of Response and Restoration.

Oil tank damaged during Hurricane Katrina.

During Hurricane Katrina in 2005, one of the Chevron oil terminal’s storage tanks was severely damaged on top, possibly after being hit by something extremely large carried by the storm waters. (NOAA)

On August 29, 2005, not far from Chevron Pipe Line Company’s oil terminal in Buras, Louisiana, Hurricane Katrina made landfall. Knowing the storm was approaching, residents left the area, and Chevron shut down the crude oil terminal, evacuating all personnel.

The massive storm’s 144 mile per hour winds, 18 foot storm tide, and waves likely twice the height of the surge put the terminal under water. At some point during the storm, one of the terminal’s storage tanks was severely damaged on top, possibly after being hit by something extremely large carried by the storm waters. The tank released crude oil into an adjacent retention pond designed to catch leaking oil, which it did successfully.

However, just a few short weeks later, Hurricane Rita hit the same part of the Gulf and the same oil terminal. Much of the spilled oil was still being contained on the retention pond’s surface, and this second hurricane washed the oil into a nearby marsh.

A Double Impact

Built in 1963, Chevron’s facility in Buras is one of the largest crude oil distribution centers in the world and is located on a natural levee on the east bank of the Mississippi River. These back-to-back hurricanes destroyed infrastructure at the terminal as well as in the communities surrounding it. Helicopter was the only way to access the area in the weeks that followed.

Chevron wildlife biologist and environmental engineer Jim Myers witnessed the storms’ aftermath at the terminal. He described trees stripped of leaves, and mud and debris strewn everywhere, including power lines. Dead livestock were found lying on the terminal’s dock. And black oil was trapped in the marsh’s thick mesh of sedge and grass. This particular marsh is part of a large and valuable ecosystem where saltwater from the Gulf of Mexico and freshwater from the Mississippi River come together.

Even after using boom and skimmers to remove some oil, an estimated 4,000 gallons of oil remained in the 50 acre marsh on the back side of the terminal. Delicate and unstable, marshes are notoriously difficult places to deal with oil. The chaos of two hurricanes only complicated the situation.

Decision Time

Once the terminal’s substantial cleanup and repair activities began, an environmental team was assembled to consider options for dealing with the oiled marsh. Dr. Amy Merten and others from NOAA’s Office of Response and Restoration, Jim Myers and others from Chevron, and personnel from the U.S. Coast Guard, Louisiana Department of Wildlife and Fisheries, and U.S. Fish and Wildlife Service rounded out this team.

The team considered several options for treating the marsh, but one leapt to the top of the list: burning off the oil, a procedure known as in situ burn. In situ burning was the best option for several reasons: the density and amount of remaining oil, remote location, weather conditions, absence of normal wildlife populations after the storms, and the fact that the marsh was bound on three sides by canals, creating barriers for the fire. Also, for hundreds of years, the area had seen both natural burns (due to lightning strikes) and prescribed burns, with good results.

Yet this recommendation met some initial resistance. In situ burning was a more familiar practice for removing oil from the open ocean than from marshes, though its use in marshes had been well-reviewed in scientific studies. Still, in the midst of a hectic and widespread response following two hurricanes, burning oil out of marshes seemed like a potentially risky move at the time.

Furthermore, some responders working elsewhere followed conventional wisdom that the oil had been exposed to weathering processes for too long to burn successfully. However, the oil was so thick on the water’s surface and so protected from the elements by vegetation that the month-old oil behaved like freshly spilled oil, meaning it still contained enough of the right compounds to burn. The environmental team tested the oil to demonstrate it would burn before bringing the idea to those in charge of the post-hurricane pollution cleanup, the Unified Command.

Burn Notice

Left: Burning marsh. Right: Same view of green marsh 10 years later.

Similar views of the same marsh where the 2005 oil spill and subsequent burn occurred after Hurricanes Katrina and Rita. The view on the right is from August of 2015. (NOAA)

Fortunately, the leader of the Unified Command approved the carefully crafted plan to burn the oiled marsh. The burns took place on October 12 and 13, 2005, a month and a half after the spill. After dividing and cutting the affected marsh into a grid of six plots, responders burned two areas each day, leaving two plots unburned since they were negligibly oiled and did not have the right conditions to burn.

Lit with propane torches, the fire on the first day was dramatic, generating dense black smoke and burning for three hours, the result of burning the part of the marsh closest to the terminal, where the oil was thickest. The second fire generated less smoke but burned longer, for about four and half hours. Afterward, you could see how the burn’s footprint matched where different levels of oil had been.

Observations after the fact assured the environmental team that most (more than 90 percent) of the oil had been burned in the four treated areas. Small pockets of unburned oil were collected with sorbent pads, and any residual oil was left to degrade naturally. Within 24 hours of burning, traces of regrowth were visible in the marsh, and in less than a month, sedge grasses had grown to a height of one to two feet, according to Myers.

A Marsh Reborn

Healthy lush marsh vegetation at water's edge.

The marsh that was oiled after Hurricanes Katrina and Rita in 2005, and subsequently burned to remove the oil. This is how it looked in August of 2015, showing an abundance of diverse vegetation. (NOAA)

Ten years later, in August of 2015, I was curious to see how the marsh had come back. I had seen many photos of during and after the burn, and subsequent reports were that the endeavor had been a great success.

Knowing I would be in the New Orleans area on vacation, I was pleased to learn that Jim Myers would be willing to give me a tour of this marsh. I met him at the ferry dock to cross to the east side of the Mississippi River and the Chevron terminal.

We looked out over the marsh from an elevated platform behind the giant oil storage tanks. All you could see were lush grasses, clumps of low trees, and birds, birds, birds. Their calls were nonstop. We saw cattails uprooted next to flattened paths leading to the water’s edge, evidence of alligators creating trails from the water to areas for basking in the sun and of cows, muskrats, and feral hogs feeding on the cattails’ roots.

The water level was high, so rather than hike through the marsh, we traveled the circumference in a flat-bottomed boat. We saw many species of birds, as well as dragonflies, freely roaming cows, fish, and an alligator.

Today, the marsh is flourishing. I could see no difference between the areas that were oiled and burned 10 years ago and nearby areas that were untouched. In fact, monitoring following the burn [PDF] found that the marsh showed recovery across a number of measures within nine months.

This marsh represents one small part of a system of wetlands that has historically provided a buffer against the high waters of past storms. Since the 1840s, when it was settled, Buras, Louisiana, has survived being hit by at least five major hurricanes. But Hurricane Katrina was different.

Gradually, marshes across the northern Gulf of Mexico have been disappearing, enabling Hurricane Katrina’s floodwaters to overwhelm areas that have weathered previous storms. Ensuring existing marshes remain healthy will be one part of a good defense strategy against the next big hurricane. Given the successful recovery of this marsh after both an oil spill and in situ burn, we know that this technique will help prevent the further degradation of marshes in the Gulf.

See more photos of the damaged tank, the controlled burn to remove the oil, and the recovered marsh 10 years later.

Find more information about the involvement of NOAA’s Office of Response and Restoration after Hurricanes Katrina and Rita.

Amy Merten with kids from Kivalina, Alaska.Amy Merten is the Spatial Data Branch Chief in NOAA’s Office of Response and Restoration. Amy developed the concept for the online mapping tool ERMA (Environmental Response Mapping Application). ERMA was developed in collaboration with the University of New Hampshire. She expanded the ERMA team at NOAA to fill response and natural resource trustee responsibilities during the 2010 Deepwater Horizon oil spill. Amy oversees data management of the resulting oil spill damage assessment. She received her doctorate and master’s degrees from the University of Maryland.


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In the Wake of the Deepwater Horizon Oil Spill, Gulf Dolphins Found Sick and Dying in Larger Numbers Than Ever Before

The Deepwater Horizon Oil Spill: Five Years Later

This is the third in a series of stories over the coming weeks looking at various topics related to the response, the Natural Resource Damage Assessment science, restoration efforts, and the future of the Gulf of Mexico.

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, Louisiana. (Louisiana Department of Wildlife and Fisheries/Mandy Tumlin)

Dolphins washing up dead in the northern Gulf of Mexico are not an uncommon phenomenon. What has been uncommon, however, is how many more dead bottlenose dolphins have been observed in coastal waters affected by the Deepwater Horizon oil spill in the five years since. In addition to these alarmingly high numbers, researchers have found that bottlenose dolphins living in those areas are in poor health, plagued by chronic lung disease and failed pregnancies.

Independent and government scientists have undertaken a number of studies to understand how this oil spill may have affected dolphins, observed swimming through oil and with oil on their skin, living in waters along the Gulf Coast. These ongoing efforts have included examining and analyzing dead dolphins stranded on beaches, using photography to monitor living populations, and performing comprehensive health examinations on live dolphins in areas both affected and unaffected by Deepwater Horizon oil.

The results of these rigorous studies, which recently have been and continue to be published in peer-reviewed scientific journals, show that, in the wake of the 2010 Deepwater Horizon oil spill and in the areas hardest hit, the dolphin populations of the northern Gulf of Mexico have been in crisis.

Troubled Waters

Due south of New Orleans, Louisiana, and northwest of the Macondo oil well that gushed millions of barrels of oil for 87 days, lies Barataria Bay. Its boundaries are a complex tangle of inlets and islands, part of the marshy delta where the Mississippi River meets the Gulf of Mexico and year-round home to a group of bottlenose dolphins.

During the Deepwater Horizon oil spill, this area was one of the most heavily oiled along the coast. Beginning the summer after the spill, record numbers of dolphins started stranding, or coming ashore, often dead, in Barataria Bay (Venn-Watson et al. 2015). One period of extremely high numbers of dolphin deaths in Barataria Bay, part of the ongoing, largest and longest-lasting dolphin die-off recorded in the Gulf of Mexico, persisted from August 2010 until December 2011.

In the summer of 2011, researchers also measured the health of dolphins living in Barataria Bay, comparing them with dolphins in Sarasota Bay, Florida, an area untouched by the Deepwater Horizon oil spill. Differences between the two populations were stark. Many Barataria Bay dolphins were in very poor health, some of them significantly underweight and five times more likely to have moderate-to-severe lung disease. Notably, the dolphins of Barataria Bay also were suffering from disturbingly low levels of key stress hormones which could prevent their bodies from responding appropriately to stressful situations. (Schwacke et al. 2014)

“The magnitude of the health effects that we saw was surprising,” said NOAA scientist Dr. Lori Schwacke, who helped lead this study. “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.”

The types of illnesses observed in live Barataria Bay dolphins, which had sufficient opportunities to inhale or ingest oil following the 2010 spill, match those found in people and other animals also exposed to oil. In addition, the levels of other pollutants, such as DDT and PCBs, which previously have been linked to adverse health effects in marine mammals, were much lower in Barataria Bay dolphins than those from the west coast of Florida.

Dead in the Water

Based on findings from the 2011 study, the outlook for dolphins living in one of the most heavily oiled areas of the Gulf was grim. Nearly 20 percent of the Barataria Bay dolphins examined that year were not expected to live, and in fact, the carcass of one of them was found dead less than six months later (Schwacke et al. 2014). Scientists have continued to monitor the dolphins of Barataria Bay to document their health, survival, and success giving birth.

Considering these health conditions, it should come as little surprise that record high numbers of dolphins have been dying along the coasts of Louisiana (especially Barataria Bay), Alabama, and Mississippi. This ongoing, higher-than-usual marine mammal die-off, known as an unusual mortality event, has lasted over four years and claimed more than a thousand marine mammals, mostly bottlenose dolphins. For comparison, the next longest lasting Gulf die-off (in 2005–2006) ended after roughly a year and a half (Litz et al. 2014 [PDF]).

Researchers studying this exceptionally long unusual mortality event, which began in February 2010, identified within it multiple distinct groupings of dolphin deaths. All but one of them occurred after the Deepwater Horizon oil spill, which released oil from April to July 2010, and corresponded with areas exposed heavily to the oil, particularly Barataria Bay (Venn-Watson et al. 2015). In early 2011, the spring following the oil spill, Mississippi and Alabama saw a marked increase in dead dolphin calves, which either died late in pregnancy or soon after birth, and which would have been exposed to oil as they were developing.

The Gulf coasts of Florida and Texas, which received comparatively little oiling from the Deepwater Horizon spill, did not see the same significant annual increases in dead dolphins as the other Gulf states (Venn-Watson et al. 2015). For example, Louisiana sees an average of 20 dead whales and dolphins wash up each year, but in 2011 alone, this state recorded 163 (Litz et al. 2014 [PDF]).

The one grouping of dolphin deaths starting before the spill, from March to May 2010, took place in Louisiana’s Lake Pontchartrain (a brackish lagoon) and western Mississippi. Researchers observed both low salinity levels in this lake and tell-tale skin lesions thought to be associated with low salinity levels on this group of dolphins. This combined evidence supports that short-term, freshwater exposure in addition to cold weather early in 2010 may have been key contributors to those dolphin deaths prior to the Deepwater Horizon spill.

Legacy of a Spill?

A bottlenose dolphin swims in the shallow waters along a sandy beach with orange oil boom.

A bottlenose dolphin swims in the shallow waters along the beach in Grand Isle, Louisiana, near oil containment boom that was deployed on May 28, 2010. Oil from the Deepwater Horizon oil spill began washing up on beaches here one month after the drilling unit exploded. (U.S. Coast Guard)

In the past, large dolphin die-offs in the Gulf of Mexico could usually be tied to short-lived, discrete events, such as morbillivirus and marine biotoxins (resulting from harmful algal blooms). While studies are ongoing, the current evidence does not support that these past causes are responsible for the current increases in dolphin deaths in the northern Gulf since 2010 (Litz et al. 2014).

However, the Deepwater Horizon oil spill—its timing, location, and nature—offers the strongest evidence for explaining why so many dolphins have been sick and dying in the Gulf since 2010. Ongoing studies are assessing disease among dolphins that have died and potential changes in dolphin health over the years since the spill.

As is the case for deep-sea corals, the full effects of this oil spill on the long-lived and slow-to-mature bottlenose dolphins and other dolphins and whales in the Gulf may not appear for years. Find more information related to dolphin health in the Gulf of Mexico on NOAA’s Unusual Mortality Event and Gulf Spill Restoration websites.


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At the Bottom of the Gulf of Mexico, Corals and Diversity Suffered After Deepwater Horizon Oil Spill

The Deepwater Horizon Oil Spill: Five Years Later

This is the second in a series of stories over the coming weeks looking at various topics related to the response, the Natural Resource Damage Assessment science, restoration efforts, and the future of the Gulf of Mexico.

Very little, if any, light from the sun successfully travels to the extreme bottom of the Gulf of Mexico. At these dark depths, the water is cold and the inescapable pressure of thousands of feet of ocean bears down on everything.

Yet life in the deep ocean is incredibly diverse. Here, delicate branches of soft coral are embraced by the curling arms of brittlestars. Slender sea fans, tinged with pink, reach for tiny morsels of food drifting down like snow from above. From minute marine worms to elongated fish, the diversity of the deep ocean is also a hallmark of its health and stability.

However, this picture of health was disrupted on April 20, 2010. Beginning that day and for almost three months after, the Macondo wellhead unleashed an unprecedented amount of oil and natural gas nearly a mile beneath the ocean. In addition, the response to this oil spill released large amounts of chemical dispersant, both at the source of the leaking oil and on the ocean surface. These actions were meant to break down oil that might have threatened life at the sea surface and on Gulf shores. Nevertheless, the implications for the ocean floor were largely unknown at the time.

In the five years since the Deepwater Horizon oil spill, a number of academic and independent scientists along with state and federal agencies, including NOAA and the Bureau of Ocean Energy Management, have been collaborating to study just how this oil spill and response affected the deep ocean and seafloor of the Gulf. What they found was the footprint of the oil spill on the seafloor, stamped on sickened deep-sea corals and out-of-balance communities of tiny marine invertebrates.

A Sickened Seafloor

A part of the world difficult to reach—and therefore difficult to know—the depths of the Gulf of Mexico required a huge collaborative and technological effort to study its inhabitants. Beginning in the fall of 2010, teams of scientists set out on multiple research cruises to collect deep-sea data, armed with specialized equipment, including remotely operated vehicles (ROVs), cameras capable of withstanding the crushing pressure of the deep ocean, and devices that could bore into the ocean bottom and scoop up multiple samples of sediments at a time.

Through these efforts, researchers have uncovered large areas of the Gulf of Mexico seafloor that contain most of the oil spill’s notable deep-sea impacts. One area in particular surrounds the damaged wellhead and stretches to the southwest, following the path of the massive underwater plume of Deepwater Horizon oil. At times, up to 650 feet thick and over a mile wide, the oil plume drifted at depths more than 3,500 feet beneath the ocean surface, leaving traces of its presence on the bottom as it went (Camilli et al. 2010).

The Macondo wellhead sits at the center of a bull’s-eye–shaped pattern of harm on the seafloor, with oil-related impacts lessening in intensity farther from the oil’s source. Further tying this pattern of injury to the Deepwater Horizon spill, a conservative chemical tracer of petroleum turned up in surface seafloor sediments extending 15 miles from the wellhead (Valentine et al. 2014).

Diversity Takes a Nose Dive

Few people ever see the bottom of the deep ocean. So what do these impacted areas actually look like? Starting several months after the leaking well was capped, researchers used ROVs and special cameras to dive down roughly 4,500 feet. They found multiple deep-sea coral colonies showing recent signs of poor health, stress, and tissue damage. On these corals, the polyps, which normally extend frilly tentacles from the corals’ branching arms, were pulled back, and excessive mucus hung from the corals’ skeletons, which also revealed patches of dead tissue. All of these symptoms have been observed in corals experimentally exposed to crude oil (White et al. 2012 PDF).

Five photos of deep-sea coral showing the progression of impacts over several years.

A time series of coral showing the progression of typical impacts at a site of coral colonies located less than seven miles from the source of Deepwater Horizon oil. You can see the brown “floc” material present in November 2010 disappears by March 2011 and afterward, is replaced by fuzzy gray hydroids and the coral loses its brittlestar companion. (Credit: Hsing et al. 2013)

Many of these coral colonies were partly or entirely coated in a clumpy brown material, which researchers referred to as “floc.” Chemical analysis of this material revealed the presence of petroleum droplets with similar chemical markers to Deepwater Horizon oil. The brittlestars usually associated with these corals also appeared in strange colors and positions. Some entire coral colonies were dead.

Research teams noted these observations only at corals within roughly 16 miles of the wellhead (White et al. 2012 PDF, Fisher et al. 2014). However, many similar coral colonies located further from the spill site showed no poor health effects.

Even one and two years later, deep-sea corals within the footprint of the spill still had not recovered. Hydroids took the place of the brown floc material on affected corals. Relatives of jellies, hydroids are fuzzy, grayish marine invertebrates that are known to encrust unhealthy coral.

Life on and under the sediment at the bottom of the Gulf also suffered, with the diversity of a wide range of marine life dropping across an area roughly three times the size of Manhattan (Montagna et al. 2013). Notably, numbers of tiny, pollution-tolerant nematodes increased in areas of moderate impact but at the expense of the number and types of other species, particularly copepods, small crustaceans at the base of the food chain. These effects were related to the concentration of oil compounds in sediments and to the distance from the Deepwater Horizon spill but not to natural oil seeps.

Top row, from left,  two types of crustaceans and a mollusk. Bottom row shows three types of marine worms known as polychaetes.

Examples of some of the common but very small marine invertebrates found living on and under the Gulf of Mexico seafloor. The top row shows, from left, two types of crustaceans and a mollusk, which are more sensitive to pollution. The bottom row shows three types of marine worms known as polychaetes, which tended to dominate ocean sediments with higher oil contamination found near corals. (Courtesy of Paul Montagna, Texas A&M University)

More sensitive to pollution, fewer types and numbers of crustaceans and mollusks were found in sediments around coral colonies showing impacts. Instead, a few types of segmented marine worms known as polychaetes tended to dominate ocean sediments with higher oil contamination near these corals (Fisher et al. 2014).

A Long Time Coming

Life on the bottom of the ocean moves slowly. Deep-sea corals live for hundreds to thousands of years, and their deaths are rare events. Some of the corals coated in oily brown floc are about 600 years old (Prouty et al. 2014). The observed impacts to life in the deep ocean are tied closely to the Deepwater Horizon oil spill, but the full extent of the harm and the eventual recovery may take years, even decades, to manifest (Fisher and Demopoulos, et al. 2014).

Learn more about the studies supported by the federal government’s Natural Resource Damage Assessment for the Deepwater Horizon oil spill, which determines the environmental harm due to the oil spill and response and seeks compensation from those responsible in order to restore the affected resources.

Read more: Deepwater Horizon Oil Spill Tied to Further Impacts in Shallower Water Corals, New Study Reports


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How Ghost Fishing Is Haunting Our Ocean

No, ghost fishing has nothing to do with ghostbusters flicking fishing rods from a boat.

But what is ghost fishing? It’s a not-at-all-supernatural phenomenon that occurs when lost or discarded fishing gear remains in the ocean and continues doing what it was made to do: catch fish. These nets and traps haunt the many types of marine life unlucky enough to become snared in them. That includes species of turtles, fish, sharks, lobsters, crabs, seabirds, and marine mammals.

Fortunately, the NOAA Marine Debris Program isn’t scared off by a few fishing nets that haven’t moved on from the underwater world. For example, through the Fishing for Energy partnership, NOAA is funding projects to study and test ways to keep fishers from losing their gear in the first place and lower the impacts lost gear has on marine life and their homes.

You can learn more about these four recent projects which are taking place from the South Carolina coast to Washington’s Puget Sound. A project at the Virginia Institute of Marine Science at The College of William and Mary will pay commercial fishermen to test special biodegradable panels on crab pots. After a certain amount of time underwater, these panels will break down and begin allowing creatures to escape from the traps. If successful, this feature could help reduce the traps’ ghost fishing potential. The researchers also will be examining whether terrapin turtles, a declining species often accidentally drowned in crab pots, will bypass the traps based on the color of the entrance funnel.

Another, unrelated effort which NOAA and many others have been supporting for years is focused on fishing out the thousands of old salmon nets lost—sometimes decades ago—in Washington’s Puget Sound. These plastic mesh nets sometimes remain drifting in the water column, while other times settling on the seafloor, where they also degrade the bottom habitat.

According to Joan Drinkwin of the Northwest Straits Foundation, the organization leading the effort, “They become traps for fish, diving birds, and mammals. Small fish will dart in and out of the mesh and predators will go after those fish and become captured in the nets. And as those animals get captured in the nets, they become bait for more scavengers.”

You can watch a video about this ongoing project produced by NOAA-affiliate Oregon SeaGrant to learn more about both the problem and the solutions.

Scuba diver next to huge mass of fishing nets underwater.

This “super net” was first reported in September 2013 at Pearl and Hermes Atoll in the Northwestern Hawaiian Islands. In 2014 scuba and free divers removed this mass of fishing gear that was more than 28 feet long, 7 feet wide, and had a dense curtain that extended 16 feet deep. (NOAA)

Thousands of miles away from the Pacific Northwest, ghost nets are also an issue for the otherwise vibrant coral reefs of the Northwestern Hawaiian Islands. Every year for nearly two decades, NOAA has been removing the lost fishing nets which pile up on the atolls and small islands. This year, divers cleared away 57 tons of old fishing nets and plastic debris. One particularly troubling “super net” found this year measured 28 feet by 7 feet and weighed 11.5 tons. It had crushed coral at Pearl and Hermes Atoll and was so massive that divers had to cut it into three sections to be towed individually back to the main NOAA ship. During this year’s mission, divers also managed to free three protected green sea turtles which were trapped in various nets.

But the origins of this huge and regular flow of old fishing nets to the Northwestern Hawaiian Islands remain a mystery. The islands lay hundreds of miles from any city but also within an area where oceanic and atmospheric forces converge to accumulate marine debris from all over the Pacific Ocean.

“You’ll go out there to this remote place and pull tons of this stuff off a reef,” comments Jim Potemra, an oceanographer at the University of Hawaii at Mānoa, “that’s like going to Antarctica and finding two tons of soda cans.”

You can learn more about the NOAA Marine Debris Program’s efforts related to ghost fishing and why certain types of marine life may be more likely to get tangled up in discarded nets and other ocean trash.