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 Building B-17 Bombers to Building Habitat for Fish: The Reshaping of an Industrial Seattle River

Imagine living in as little as two percent of your home and trying to live a normal life. That might leave you with something the size of a half bathroom.

Now imagine it’s a dirty half bathroom that hasn’t been cleaned in years.

Gross, right? As Muckleshoot tribal member Louie Ungaro recently pointed out, that has been roughly the situation for young Chinook salmon and Steelhead trout for several decades as they pass through the Lower Duwamish River in south Seattle, Washington.

Salmon and Steelhead trout, born in freshwater streams and creeks in Washington forests, have to make their way to the Puget Sound and then the ocean through the Duwamish River. However, this section of river has been heavily industrialized and lacks the clean waters, fallen trees, huge boulders, and meandering side channels that would represent a spacious, healthy home for young fish.

Chair of his tribe’s fish commission, Ungaro sent a reminder that the health of this river and his tribe, which has a long history of fishing on the Duwamish and nearby rivers, are closely tied. “We’re no different than this river,” he implored. Yet he was encouraged by the Boeing Company’s recent cleanup and restoration of fish habitat along this Superfund site, a move that he hopes is “just a start.”

The Pace—and Price—of Industry

Starting as far back as the 1870s and stretching well into the twentieth century, the Lower Duwamish River was transformed by people as the burgeoning city of Seattle grew. The river was straightened and dredged, its banks cleared and hardened. Factories and other development lined its banks, while industrial pollution—particularly PCBs—poured into its waters.

More than 40 organizations are potentially responsible for this long-ago pollution that still haunts the river and the fish, birds, and wildlife that call it home. Yet most of those organizations have dragged their feet in cleaning it up and restoring the impacted lands and waters. However, the Boeing Company, a longtime resident of the Lower Duwamish River, has stepped up to collaborate in remaking the river.

Newly restored marsh and riverbank vegetation with protective ropes and fencing on the Duwamish River.

The former site of Boeing’s Plant 2 is now home to five acres of marsh and riverbank habitat, creating a much friendlier shoreline for fish and other wildlife. Protective fencing and ropes attempt to exclude geese from eating the young plants. (NOAA)

Boeing’s history there began in 1936 when it set up shop along 28 acres of the Duwamish. Here, the airplane manufacturer constructed a sprawling building known as Plant 2 where it—with the help of the women nicknamed “Rosie the Riveters”—would eventually assemble 7,000 B-17 bombers for the U.S. government during World War II. The Army Corps of Engineers even took pains to hide this factory from foreign spies by camouflaging its roof “to resemble a hillside neighborhood dotted with homes and trees,” according to Boeing.

But like many of its neighbors along the Duwamish, Boeing’s history left a mark on the river. At the end of 2011, Boeing tore down the aging Plant 2 to prepare for cleanup and restoration along the Duwamish. Working with the City of Seattle, Port of Seattle, and King County, Boeing has already removed the equivalent of thousands of railcars of contaminated sediment from the river bottom and is replacing it with clean sand.

From Rosie the Riveter to Rosie the Restorer

By 2013, a hundred years after the Army Corps of Engineers reshaped this section of the Duwamish from a nine mile estuary into a five mile industrial channel, Boeing had finished its latest transformation of the shoreline. It planted more than 170,000 native wetland plants and grasses here, which are interspersed with large piles of wood anchored to the shore.

Five acres of marsh and riverbank vegetation now line its shores, providing food, shelter, and calmer side channels for young fish to rest and grow as they transition from freshwater to the salty ocean.

Canada geese on an unrestored portion of the Duwamish River shoreline.

Protecting the newly restored shoreline, out of sight to the left, from Canada geese is a challenge to getting the young wetland plants established. Behind the geese, the artificial, rocky shoreline is a stark difference from the adjacent restored portion. (NOAA)

Now the challenge is to keep the Canada geese from eating all of the tender young plants before they have the chance to establish themselves. That is why protective ropes and fencing surround the restoration sites.

Already, biologists are beginning to see a change in the composition of the birds frequenting this portion of the river. Rather than the crows, starlings, and gulls typically associated with areas colonized by humans, birds such as herons and mergansers, a fish-eating duck, are showing up at the restoration sites. Those birds like to eat fish, which offers hope that fish such as salmon and trout are starting to make a comeback as well.

Of course, these efforts are only the beginning. Through the Natural Resource Damage Assessment process, NOAA looks forward to working with other responsible organizations along the Duwamish River to continue restoring its health, both for people and nature now and in the future.


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This Is How We Help Make the Ocean a Better Place for Coral

Large corals on the seafloor.

The ocean on its own is an amazing place. Which is why we humans like to explore it, from its warm, sandy beaches to its dark, mysterious depths. But when humans are involved, things can and often do go wrong.

That’s where we come in. Our corner of NOAA helps figure out what impacts have happened and what restoration is needed to make up for them when humans create a mess of the ocean, from oil spills to ship groundings.

In honor of World Ocean Day, here are a few ways we at NOAA make the ocean a better place for corals when ships accidentally turn them into undersea roadkill.

First, we literally vacuum up broken coral and rubble from the seafloor after ships run into and get stuck on coral reefs. The ships end up crushing corals’ calcium carbonate homes, often carpeting the seafloor with rubble that needs to be removed for three reasons.

  1. To prevent it from smashing into healthy coral nearby.
  2. To clear space for re-attaching coral during restoration.
  3. To allow for tiny, free-floating coral babies to settle in the cleared area and start growing.

Check it out:A SCUBA diver using a suction tube to vacuum coral rubble from the seafloor during coral restoration after the VogeTrader ship grounding.Sometimes, however, the broken bits get stuck in the suction tube, and you have to give it a good shake to get things moving. SCUBA divers shaking a suction tube to clear it on the seafloor.Next, we save as many dislodged and knocked over corals as we can. In this case, popping them into a giant underwater basket that a boat pulls to the final restoration site.

SCUBA diver placing coral piece into a large wire basket on the seafloor during coral restoration after the VogeTrader ship grounding.Sometimes we use “coral nurseries” to regrow corals to replace the ones that were damaged. This is what that can look like:

Staghorn coral fragments hanging on an underwater tree structure of PVC pipes.Then, we cement healthy corals to the seafloor, but first we have to prepare the area, which includes scrubbing a spot for the cement and coral to stick to.

SCUBA diver scrubbing a spot on the seafloor for the cement and coral to stick to.(And if that doesn’t work very well, we’ll bring out a power washer to get the job done.)

SCUBA diver using a power washer to clear a spot on the seafloor for the cement and coral to stick to during coral restoration after the VogeTrader ship grounding.Finally, we’re ready for the bucket of cement and the healthy coral.

SCUBA diver turning over a bucket of cement on the seafloor during coral restoration after the VogeTrader ship grounding.

Instead of cement, we may also use epoxy, nails, or cable ties to secure corals to the ocean floor.

After all that work, the seafloor goes from looking like this:

View of seafloor devoid of coral before restoration.To this:

View of seafloor covered with healthy young coral and fish after restoration due to the VogeTrader grounding.

Ta-da! Good as new, or at least, on its way back to being good-as-new.

When that’s not enough to make up for all the harm done to coral reefs hit by ships, we look for other restoration projects to help corals in the area, like this project to vacuum invasive algae off of coral reefs in Oahu.

Watch how this device, dubbed the “Super Sucker,” works to efficiently remove the yellow-brown algae that is smothering the corals:

Or, as another example of a coral restoration project, we set sail each year to the remote Papahānaumokuākea Marine National Monument in the Northwestern Hawaiian Islands to pull more than 50 tons of giant, abandoned fishing nets off of the pristine coral reefs.

In 2014, that included removing an 11 ton “monster net” from a reef:

For the most part, the coral restoration you’ve seen here was completed by NOAA and our partners, beginning in October 2013 and wrapping up in April 2014.

These corals were damaged off the Hawaiian island of Oahu in February of 2010 when the cargo ship M/V VogeTrader ran aground and was later removed from a coral reef in Kalaeloa/Barber’s Point Harbor.


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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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NOAA and Partners Work Quickly to Save Corals Hit by Catamaran in Puerto Rico

Experts estimate that thousands of corals were broken, dislodged, buried, or destroyed when the 49-foot-long catamaran M/V Aubi ran aground along the north coast of Puerto Rico the night of May 14, 2015.

Traveling from the Dominican Republic to San Juan, Puerto Rico, the recreational boat became grounded on a coral reef, causing significant damage to the reef. As the vessel was being moved, the vessel’s two hulls slowly ground further into the reef, forming mounds of coral and leaving rubble on the ocean bottom. UPDATED 5/27/2015: The area of the vessel’s direct impact is 366 square meters (not quite 4,000 square feet), while partial impact covers more than 1,000 square meters (roughly 10,764 square feet).

On the night of the grounding, responders were immediately concerned about preventing a spill of the fuel on board the Aubi. The fuel had to be removed from the fuel tanks in the aluminum hulls of the catamaran before it was moved off of the coral reefs. By the evening of May 15, approximately 1,500 gallons of fuel had been removed successfully, readying the vessel to be towed from the reef. It was pulled free during high tide the next morning.

The location of the grounding is in a Puerto Rico Marine Reserve, overseen by the Puerto Rico Department of Natural and Environmental Resources.

Crushing News and Rubble Rousers

The species of coral affected by the accident are mostly Diploria, or brain coral, and Acropora palmata, or elkhorn coral. Listed as threatened under the Endangered Species Act, elkhorn coral is one of the most important reef-building corals in the Caribbean. Brain coral, found in the West Atlantic Ocean and the Caribbean, is also an important reef-building coral and is known for its stony, brain-like appearance.

Although there was significant damage to the coral, an oil spill fortunately was prevented. While exposure to oil may kill corals, it more frequently reduces their ability to perform photosynthesis and causes growth or reproductive problems.

A multi-organizational team, which included NOAA, was able to salvage over 800 coral colonies (or fragments of colonies), moving them into deeper water nearby for temporary holding.  About 75 very large colonies of brain coral were righted but unable to be moved because of their size.

Broken brain coral on seafloor.

Brain coral (Diploria) and elkhorn coral (Acropora palmata) represent the majority of the coral species affected by this vessel grounding. (NOAA)

With buckets and by hand, the team filled 50 loads of rubble (approximately nine cubic yards) into open kayaks and small boats to transport them to a deeper underwater site that Puerto Rico Department of Natural Resources had approved for dumping.  All that material, moved in one day, would otherwise likely have washed into the healthy reef adjacent to the damaged one and potentially caused even more harm.

While poor weather has been preventing further work at the grounding site this past week, the team expects to restart work soon. Once that happens, initial estimates are that it will take 10-15 days to reattach the salvaged corals and to secure the rubble most at risk of moving. Stabilizing or removing the remaining rubble and rebuilding the topographic complexity of the flattened seafloor, accomplished using large pieces of rubble, would likely take an additional 10 days.

Both the location and nature of the corals dominating the area make it a very viable location for complete restoration using nursery-grown corals, but the scope and scale would still need to be determined.

Small Boat, Big Impact?

Healthy brain coral on seafloor.

An area of healthy corals near the site of the grounded M/V Aubi. Divers acted quickly to protect these corals from being damaged by the large amounts of rubble loose on the seafloor after the accident. (NOAA)

Even though the vessel involved in this grounding was relatively small, an unofficial, anecdotal report from the team working on the site noted that the amount of damage appeared comparable to that caused by the groundings of much larger vessels, such as tankers.

If not for the quick work of the U.S. Coast Guard, Puerto Rico Department of Natural Resources, NOAA, support contractors, volunteers from non-governmental organizations, and members of the local community, the damage could have been much worse.

Healthy coral reefs are among the most biologically and economically valuable ecosystems on earth.

According to NOAA’s Coral Reef Conservation Program, a little-known fact is that corals are in fact animals, even though they may exhibit some of the characteristics of plants and are often mistaken for rocks.

Learn more about how NOAA dives to the rescue of corals in the Caribbean when they become damaged by grounded ships.


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Transforming Dusty Fields into Vibrant Salt Marshes in San Francisco Bay

Vibrant marsh with lots of ducks and trucks on the highway in the background.

Just after the Cullinan Ranch restoration site was re-flooded, huge flocks of waterfowl began using the marsh, including Canvasback, Scaup, Northern Pintail, Mallards, and American Wigeon. (Ducks Unlimited)

What happens when you fill a dry, dusty 1,200 acre field at the northern edge of San Francisco Bay with tide waters unseen in that place for more than a century?

You get a marsh with a brand new lease on life.

In January 2015, this is exactly what took place at the salt marsh restoration site called Cullinan Ranch (known as that due to its history as a hay farm).

Check out the photos taken of the restoration site in November 2013, after the new boat ramp and wildlife viewing platform were built but before the levees holding back the bay were breached, and compare them with those taken in the same spot in January 2015, after the waters returned.

Brackish waters once again cover the low-lying area, long pushed down below sea level due to farming dating back to the 1880s. The presence of salt water has transformed this arid field into tidal wetland habitat, where birds, fish, and wildlife, such as the endangered Ridgway’s rail, the salt marsh harvest mouse, steelhead, Chinook salmon, and other fish can thrive.

According to Ducks Unlimited biologist Craig Garner, whose organization has been a key player in this site’s restoration, “When the ranch was newly flooded, we saw a tremendous response by waterfowl. Large numbers of birds were recorded using the area, particularly Canvasback,” a species of diving duck.

Could it be that Cullinan Ranch provides California wildlife with a new refuge from the current scarcity of freshwater habitats further inland? Garner suggests, “Though it is tough to gauge without waterfowl survey data, I would say that Cullinan Ranch could be offsetting the effects of drought conditions on diving duck habitat at all” levels of the tidal cycle.

Of course, people will also be able to enjoy this transformation occurring at Cullinan Ranch via the new recreational facilities. (Launching your boat into a dry field probably wouldn’t be much fun, after all.)

But it’s not just fun and games. People will benefit from this renewed salt marsh acting as a natural filter, increasing the quality of the water passing through it on the way to the bay and its fisheries, and as a sponge for moderating flooding during storms. The plant life growing in the marsh also serves to capture and hold excess carbon dioxide from the nearby urban areas. In addition, taking out the 19th-century levees holding out the bay’s tides reduces the chances of a catastrophic failure and cuts out the expense of maintaining poorly built levees.

Watch as the last satisfying scoops of the muddy barrier disappear and salty waters rush in:

Excavator removing a dirt levee and allowing tide waters to rush into a dry marsh.

Taking out the first levee at the Cullinan Ranch marsh restoration project in central California in January 2015. (NOAA)

Learn more about the efforts to restore this tidal wetland and another long-dry area known as Breuner Marsh. Both of these restoration projects were made possible with funding from a natural resource damage assessment settlement paid by Chevron to make up for years of dumping mercury and oil pollution from its Richmond, California, refinery into the shallow waters of nearby Castro Cove. NOAA partnered with the U.S. Fish and Wildlife Service and the California Department of Fish and Wildlife to achieve the 2010 Chevron settlement and contribute to these two important restoration projects.

In the fall of 2014, Breuner Marsh also saw the return of its daily infusion of saltwater and is looking more and more like a natural salt marsh and less like the next site of urban development.

Aerial view of marsh with tide waters channeling across the shore.

An aerial view of the tide waters retaking their normal course at the restoration site Breuner Marsh on San Francisco Bay in the fall of 2014. (Castro Cove Natural Resource Damage Trustees)


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NOAA Launches New Data Management Tool for Public Access to Deepwater Horizon Oil Spill Data

Two people launch a water column sampling device off the side of a ship.

Launching a device to take measurements in the water column during the 2010 Deepwater Horizon oil spill. NOAA built the online tool DIVER to organize and provide access to these scientific data and the many others collected in the wake of the spill. (NOAA)

A flexible new data management tool—known as DIVER and developed by NOAA to support the Natural Resource Damage Assessment (NRDA) for the 2010 Deepwater Horizon oil spill—is now available for public use. DIVER stands for “Data Integration, Visualization, Exploration and Reporting,” and it can be accessed at https://dwhdiver.orr.noaa.gov.

DIVER was developed as a digital data warehouse during the Deepwater Horizon oil spill response effort and related damage assessment process, which has required collecting and organizing massive amounts of scientific data on the environmental impacts of the spill.

The tool serves as a centralized data repository that integrates diverse environmental data sets collected from across the Gulf of Mexico ecosystem. It allows scientists from different organizations and laboratories located across the country to upload field data, analyses, photographs, and other key information related to their studies in a standardized format. DIVER thus brings together all of that validated information into a single, web-based tool.

In addition, DIVER provides unprecedented flexibility for filtering and downloading validated data collected as part of the ongoing damage assessment efforts for the Gulf of Mexico. The custom query and mapping interface of the tool, “DIVER Explorer,” provides both a data filter and review tools, which allow users to refine how they look for data and explore large data sets online. Query results are presented in an interactive dashboard, with a map, charts, table of results, metadata (data about the data), and sophisticated options for exporting the data.

View of DIVER Explorer map and query results for environmental impact data in the Gulf of Mexico.

A view of DIVER Explorer query results shown in an interactive dashboard. (NOAA)

In addition to the DIVER Explorer query tools, this website presents a detailed explanation of our data management approach, an explanation of field definitions and codes used in the data warehouse, and a robust help section.

Currently, DIVER provides access to nearly 4 million validated results of analytical chemistry from over 50,000 samples of water, tissue, oil, and sediment collected by federal, state, academic, and nongovernmental organizations to support the Deepwater Horizon damage assessment. As additional data sets become publicly available they will be accessible through the DIVER Explorer tool.

Read the announcement of this tool’s public launch from the NOAA website.


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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.

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