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

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Remembering the Veterans That Served America and the Historic Shipwrecks They Left Behind

This is a post by the Office of Response and Restoration’s Donna Roberts.

Did you know that over 20,000 shipwrecks rest on the ocean floor off our coasts? The past century of commerce and warfare has left us with this legacy of sunken vessels dotting the seafloor around the United States.

While some of these are naval vessels, a large proportion are merchant vessels destroyed during war time. These wrecks are skewed heavily to World War II casualties such as those fallen during the “Battle of the Atlantic.” Some wrecks, such as the Civil War casualty, the USS Monitor, have been listed as National Historic Landmarks or on the National Register of Historic Places. Many of them, such as the USS Arizona at Pearl Harbor, Hawaii, are either civilian or military grave sites.

Beyond their military and historic significance, these wrecks also represent an enormous human toll. Today—on Veterans Day in the United States, Armistice Day or Remembrance Day in other nations—we honor the men and women who have served in the armed forces of all nations, as well as those serving in the Merchant Marine, and commemorate those who gave their lives in that service.

The Terrible Cost of the Battle of the Atlantic

During World War II’s Battle of the Atlantic, which lasted from September 1939 until the defeat of Germany in 1945, German U-boats and warships (and later Italian submarines) were pitted against Allied convoys transporting military equipment and supplies across the Atlantic to Great Britain and the Soviet Union. This battle to control Atlantic shipping lanes involved thousands of ships and stretched across thousands of square miles of ocean.

A Coast Guard ship's crew watches an explosion in the water ahead.

On April 17, 1943, Coast Guardsmen on the deck of the U.S. Coast Guard Cutter Spencer watch the explosion of a depth charge that blasted a Nazi U-boat’s hope of breaking into the center of a large convoy of ships. World War II left thousands of Allied and Axis ships — and soldiers — on the bottom of the ocean. (U.S. Coast Guard)

The losses in the battle were staggering. Between January and June 1942 alone, this battle resulted in the sinking of almost 500 ships. Historians estimate that more than 100 convoy battles took place during the war, costing Britain’s Merchant Navy more than 30,000 men and around 3,000 ships. The terrible cost for the Germans was 783 U-boats and 28,000 sailors, about 75% of the U-boat force. Although casualty statistics vary, we know that the U.S. Merchant Mariners suffered the highest rate of marine casualties of any service in World War II.

While many of these sunken vessels in U.S. waters rest in the Atlantic Ocean or Gulf of Mexico, numerous wrecks, such as the S/S Montebello, can be found in the Pacific. And of course, the wartime toll was spread across the world’s oceans, touching nearly all parts of the globe.

NOAA’s Role with Undersea Wrecks

NOAA is involved with shipwrecks in a number of ways. The agency’s role ranges from offering scientific guidance to the U.S. Coast Guard during pollution responses, to stewarding the diverse natural and cultural resources including shipwrecks in national marine sanctuaries, to creating navigational charts that show the precise locations of wrecks that could hinder maritime traffic. Most of the 20,000 wrecks resting off our coasts are old and did not carry oil as fuel or hazardous cargo; however, some of the more recent wrecks have the potential to contain—and sometimes leak—oil.

In 2002, for example, the decaying wreck of the S/S Jacob Luckenbach (carrying supplies to support the Korean War) was identified as the source of mysterious, recurring oil spills that had killed thousands of seabirds and other marine life along California’s coast. Our office joined with the U.S. Coast Guard and other agencies to remove the approximately 100,000 gallons of oil remaining in the wreck, protect the resources of the Great Farallones National Marine Sanctuary, and restore critical seabird breeding habitat in the U.S. and Canada to make up for the harm caused by the oil releases.

Two divers and a shark swim next to a large shipwreck.

Knowing how shipwreck sites formed helps explain why sunken vessels, like the Dixie Arrow which initially carried approximately 86,136 barrels of crude oil, but was demolished during World War II, no longer remain intact and are no longer potentially polluting shipwrecks. (NOAA)

Leaking wrecks like the Jacob Luckenbach are one reason NOAA maintains a large database of shipwrecks, dumpsites, navigational obstructions, underwater archaeological sites, and other underwater cultural resources, known as the Resources and Undersea Threats (RUST) database.

Beginning in 2010, NOAA’s Office of Response and Restoration and Office of National Marine Sanctuaries systematically analyzed a subset of those wrecks which could pose a substantial threat of leaking oil still on board. This work is part of NOAA’s Remediation of Underwater Legacy Environmental Threats (RULET) project. (Read more about the work conducted and the final report (PDF).) After the report was completed in 2013, the U.S. Coast Guard has worked to incorporate the information and recommendations into their regional contingency plans.

NOAA also has the privilege of protecting shipwrecks and naval battlefields though its National Marine Sanctuaries office. The first NOAA national marine sanctuary was designated in 1975 to protect the U.S. Navy warship USS Monitor, and other sanctuaries have followed in these footsteps of preserving historic wrecks. Today, you can explore fascinating undersea wrecks at Florida Keys National Marine Sanctuary, Thunder Bay National Marine Sanctuary in the Great Lakes, and at other sanctuaries.

Wrecks and Reefs

Sometimes these submerged shipwrecks can serve as artificial reefs. Sunken wrecks are actually the most prevalent type of artificial reef. As artificial reefs, shipwrecks can create both amazing homes for a diversity of marine life and popular attractions for commercial and recreational fishers, divers, and snorkelers.

Occasionally, vessels are even sunk intentionally for this purpose. However, it can be very costly to prepare the vessels to become artificial reefs, which requires removing paints and other hazardous materials in the hull. Another consideration is the stability of the vessel and its danger to living things around it. For example, if the vessel is in shallow water, will it flip over in a storm and crush the new coral growing there? Could people or marine life get caught inside it? These considerations are why artificial reefs are often found in deep water and why establishing an artificial reef requires special review and permitting processes.

Through the study, protection, and promotion of our diverse legacy of undersea wrecks, national marine sanctuaries help us learn more about and celebrate our merchant marine and military history.

Explore Shipwrecks While Staying Dry

You can learn more about NOAA expeditions between 2008 and 2011, which explored the World War II wrecks in the “Graveyard of the Atlantic.”

You also can watch a video of researchers first discovering the long-lost location of the USS Monitor’s wreck in 1973 off the coast of North Carolina:

See what it’s like to dive among the many wrecks at the bottom of Lake Huron in Thunder Bay’s “Shipwreck Alley”:

Take a video tour of the wreck of the USS Arizona, sunk by Japanese planes on December 7, 1941, and pay homage to the members of the U.S. armed forces who gave their lives.

Video frame of a diver exploring a shipwreck.

Donna Roberts

Donna Roberts

Donna Roberts is a writer for the Emergency Response Division of NOAA’s Office of Response and Restoration (OR&R). Her work supports the OR&R website and the Environmental Sensitivity Index mapping program.

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

Sick sea fan with discolored branches and hydroids covering it.

After the Deepwater Horizon oil spill, researchers found significant injuries in at least four species of sea fans along the Gulf’s continental shelf. Damage primarily took the form of overgrowth by hydroids (fuzzy marine invertebrates characteristic of unhealthy corals) and broken or bare branches of coral. (Credit: Ian MacDonald/Florida State University)

In the months and years after the 2010 Deepwater Horizon oil spill, damage and poor health were found in a swath of deep-sea coral reefs and related marine life at the bottom of the Gulf of Mexico.

Within roughly 16 miles of the leaking wellhead, researchers discovered sickened and damaged deep-sea corals, often coated in a clumpy brown material containing petroleum, and the sediments showed evidence of out-of-balance communities of tiny invertebrates inhabiting the seafloor sediments, whose diversity took a nose dive after the spill.

Now, a study published in October 2015 in the journal Coral Reefs reveals that this footprint of damage also extends to coral communities in shallower Gulf waters, up to 67 miles from the wellhead. In this latest study, researchers from NOAA, Florida State University, and JHT Inc. used video and images from remotely operated vehicles (ROV) to compare the health of corals on hard-bottom reefs in the “mesophotic zone” before and after the oil spill.

The mesophotic zone of the ocean receives low levels of light but supports abundant fish, corals, and sponges. The reefs in this study are important sources of habitat, food, and shelter for various marine life. These vibrant reefs also support recreational and commercial fishing for species such as snapper and grouper. Located in a region called the “Pinnacle Trend,” they are at the edge of the continental shelf off Louisiana, Mississippi, and Alabama, roughly 200-300 feet below the surface.

Previous oil spill studies focused on deep-sea coral communities 4,000 feet under the ocean, located near the leaking wellhead. While the Pinnacle Trend reefs are shallower and more remote, they were below the surface oil slick that persisted for several weeks.

What Lies Beneath

Three of the largest reefs at Pinnacle Trend—bearing the colorful names Alabama Alps Reef, Roughtongue Reef, and Yellowtail Reef—were located beneath the surface slick of Deepwater Horizon oil for three to five weeks in the summer of 2010. Located between 35 and 67 miles from the leaking well, corals on the reefs were likely to have been exposed to oil and dispersant that sank from the surface down toward the seafloor. These reefs were measured against two other reef sites more than 120 miles beyond the leaking well and below the Deepwater Horizon oil slick less than three days.

Graphic showing a profile of the Gulf of Mexico's seafloor habitats from shore out to the leaking wellhead.

A profile of the Gulf of Mexico seafloor habitats extending from the shore to depths around the Macondo wellhead. The mesophotic coral reefs in this study were located at the edge of the continental shelf. (NOAA/Kate Sweeney)

Because researchers had access to ROV footage of these coral reefs dating back as far as 1989, they could directly measure what level of injury could be considered “normal” for each reef. After all, this area of the Gulf is known to be susceptible to impacts from fishing methods that contact the sea bottom. Researchers suspect that fishing was the cause of injuries observed at the two sites far from the spill because lines were wrapped around many of the coral colonies.

Not a (Sea) Fan of Damaged Corals

The three reefs closer to the wellhead had less evidence of fishing but showed major declines in health after the oil spill in 2010. More than half of the coral colonies at these sites showed signs of damage by 2011, compared with less than 10% before the spill. In comparison, the sites further from the wellhead had no significant change before and after the Deepwater Horizon oil spill.

In addition, injured corals the scientists noted in 2011 continued to deteriorate in the years that followed, “suggesting recovery of injured corals is unlikely,” said lead author Dr. Peter Etnoyer of NOAA. Healthy corals noted after the incident in 2011 remained healthy through the end of the study in 2014, suggesting the injured corals would have been healthy but for the spill.

The researchers in this most recent study noted significant injuries among at least four species of large gorgonian octocorals (sea fans) in the three impacted reefs. Injuries took the form of overgrowth by hydroids (fuzzy marine invertebrates characteristic of unhealthy corals) and broken or bare branches of coral. To a lesser extent, corals also appeared severely discolored, with eroded polyps, had lost limbs, or toppled over entirely.

An earlier study of these mesophotic reefs by some of the same scientists in the journal Deep Sea Research detected low levels of a petroleum compound known as polycyclic aromatic hydrocarbons (PAHs) in coral tissues and nearby seafloor sediments. The levels were low compared to sites near the wellhead, but at this point, no one yet has established what constitutes a toxic level of these compounds to marine life in mesophotic coral communities.

“The corals of the Pinnacle Trend require decades to reach maturity,” said Florida State University scientist Ian MacDonald, who also contributed to the study. “Recovery will require years and it may not be immediately apparent whether the injured colonies are being replaced with new settlements. Our task is to study the process—to learn as much as we can and to ensure that nothing impedes this vital natural process.”

“The results presented here may vastly underestimate the extent of impacts to mesophotic reefs in the northern Gulf of Mexico,”  the researchers commented, since the reefs in this study represent less than 3 percent of the mesophotic reef habitat that was known to occur beneath the oil slick. “The reefs have some prospects for recovery since many healthy colonies remain,” said Etnoyer. NOAA and its partners on this study recommend efforts to protect and restore the Pinnacles Trend reefs in order to conserve the corals and fish along this part of the ocean floor.


Watch Divers Restore Coral Reefs Hit by a Huge Ship in Hawaii

Coral reefs are not to be confused with underwater highways. Unfortunately for the corals, however, navigating huge ships is a tricky business and sometimes reefs do end up on the wrong side of the “road.” (One reason why having up-to-date navigational charts is so important!)

This was the case for corals 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.

NOAA’s Restoration Center and the State of Hawaii worked quickly to implement emergency restoration (using what look like laundry baskets), using special underwater scientific techniques and technologies, and ultimately restoring the reef after getting some help from vacuums, power washers, and even winter storms.

See divers transform these Hawaiian corals from crushed to flush with marine life:

In the end, these efforts are all part of how we work to help make the ocean a better place for corals and the many other types of marine life that rely on them.

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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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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.


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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How Do You Keep Invasive Species out of America’s Largest Marine Reserve?

A young monk seal and birds on the beach of French Frigate Shoals in the Northwestern Hawaiian Islands.

The coral reefs of Papahānaumokuākea Marine National Monument are the foundation of an ecosystem that hosts more than 7,000 species, including marine mammals, fishes, sea turtles, birds, and invertebrates. Many are rare, threatened, or endangered, including the endangered Hawaiian monk seal. At least one quarter are found nowhere else on Earth. (NOAA)

From Honolulu, it takes a day and a half to get there by boat. But Scott Godwin, an expert in the ways “alien” marine life can travel and take hold in new places, knows what is at risk. He understands perfectly well what might happen if a new species manages to make that journey to the remote and incredible area under his watch.

Godwin works for the Resource Protection Program in NOAA’s Office of National Marine Sanctuaries. Along with the U.S. Fish and Wildlife Service and State of Hawaii, he is charged with protecting Papahānaumokuākea Marine National Monument, a tall order considering that it is one of the largest marine conservation areas in the world. This monument includes an isolated chain of tropical islands, atolls, and reefs hundreds of miles northwest of the main Hawaiian Islands—appropriately known as the Northwestern Hawaiian Islands—as well as nearly 140,000 square miles of surrounding waters. The monument is home to a host of rare and unique species, some found exclusively within its borders, as well as some of the healthiest and least disturbed coral reefs on Earth.

Map of main and Northwestern Hawaiian Islands

Papahānaumokuākea Marine National Monument is the single largest fully protected conservation area under the U.S. flag, and one of the largest marine conservation areas in the world. It encompasses 139,797 square miles of the Pacific Ocean — an area larger than all the country’s national parks combined. (NOAA)

And it is Godwin’s job to keep it that way. Along with climate change and marine debris, invasive species have been identified as one of the top three threats to this very special place, which, in addition to being a national monument, is also a national wildlife refuge and United Nations World Heritage Site. Fortunately, invasive species also happen to be Godwin’s area of expertise.

If new species were to break into the monument’s borders—and in some cases, they already have—the risk is of them exhibiting “invasive” behavior. In other words, outcompeting the native marine life among the coral reefs and taking the lion’s share of the most valuable resources: food and space.

But considering how remote and expansive the area is—the Northwestern Hawaiian Islands stretch across 1,200 nautical miles and are closed to the general public—how would anything find its way there in the first place?

Yet help from humans is how many species arrive in new environments, including the main Hawaiian Islands, where more than 400 non-native marine species are established. That means ships and other human activity coming from Hawaii represent the greatest potential for bringing invasive species into the monument.

Packing List: Bleach, Deep Freezer, and Quarantine Clothes

Dianna Parker of the NOAA Marine Debris Program learned this lesson firsthand. In October 2014, she and colleague Kyle Koyanagi joined a team of NOAA divers from the Pacific Islands Fisheries Science Center (PIFSC) on a mission to Papahānaumokuākea Marine National Monument to remove the tons of old fishing nets that wash up on its coral reefs each year.

In the months leading up to her departure from Honolulu, Parker learned she would need something called “quarantine clothes.” In essence, they were a brand-new set of clothes set aside for each time she would step on dry land in the Northwestern Hawaiian Islands. Furthermore, these new clothes had to be sealed in plastic bags and stored in a walk-in freezer for 48 hours before she could wear them. That made for a chilly start to the day, as Parker recalled.

The quarantine clothes were part of a U.S. Fish and Wildlife Service protocol for limiting both the introduction of foreign species into the monument and the spread of species between islands within it. “Something that’s native to one tiny island could be alien to the next one down the chain,” said Parker. The transmission could happen via a spore on your shoe or a seed stuck to your shirt.

In addition, all of the gear and equipment they were using, such as wet suits, fins, and life vests, had to be soaked in a dilute bleach solution before being used in a new location, a protocol developed by NOAA.

For the roughly month-long mission, Parker brought six full outfits to wear on the six islands the ship planned to visit. In the end, she only visited five islands and was able to turn a t-shirt from the sixth outfit into a makeshift hat to keep the hot sun at bay.

“Having to go through that level of precaution to not bring invasive species into the monument makes you realize just how delicate things are up there,” reflected Parker.

Stowaways Not Welcome

But before Parker and the rest of her team left on their mission, the vessel that would carry them, the NOAA Ship Oscar Elton Sette, first had to undergo a thorough cleaning and inspection before being granted a permit to enter the monument. The hull was scrubbed and checked by specially trained divers for even as much as a rogue barnacle. Ballast water, the water held in tanks on a ship to provide stability, was inspected closely as well because numerous creatures worldwide have been documented hitching a secret ride this way. And, of course, the ship was examined for rats, the perennial stowaways.

However, rats arrived in the monument years ago via the U.S. military activity previously based on Midway Atoll, a strategic naval base during World War II and the Cold War, and French Frigate Shoals, a runway and refueling stop for planes headed to Midway during World War II. While efforts to eradicate rats at these former military bases were successful, attempting a similar project for underwater species would be much more challenging. Marine species spread very quickly and human activities are necessarily limited by the finite amount of time we can spend underwater.

Currently, Godwin has documented about 60 non-native marine species in the Papahānaumokuākea Marine National Monument, mainly at Midway, but these species—the majority of which are marine invertebrates such as tube worms and sea squirts—are not recent arrivals. Most likely harken back to the area’s military days, which ended in 1994. Today the easiest way for a new marine species to get a foothold on these reefs is by colonizing “disturbed habitat,” or areas humans have altered, such as seawalls or docks, as is the case at Midway and French Frigate Shoals.

“Competition with native species is pretty stiff,” admits Godwin. While marine life from outside the monument can become established, they often don’t have the opportunity to become invasive, he said. “But we never say never,” which is why he helps train NOAA divers going to the monument to recognize the aggressive behaviors of marine invasive species.

Marine Debris and Surprises from Japan

Person pulling bio-fouled net out of water into boat with diver's help.

NOAA divers examining the abandoned fishing nets for potentially invasive species, as they were removing them from the Northwestern Hawaiian Islands in October 2014. (NOAA)

Godwin was on high-alert, however, when debris washed away from Japan during the 2011 tsunami began showing up in Hawaii. Most marine debris in the Northwestern Hawaiian Islands comes in the form of fishing nets typically lost in the open ocean—the kind the NOAA PIFSC team was clearing from reefs. Many of the species colonizing these nets are native to the open ocean and generally do not survive in the monument’s coastal environment.

But the boats and other debris from Japan came from the coast, bringing with them the hardy and flexible marine life capable of surviving the transoceanic journey until they found another coastal home. Fortunately, Godwin found that none of the non-native Japanese species showing up on tsunami debris became established in either Hawaii or the monument.

“Marine debris is a vector [for invasive species],” said Godwin, “but we have very little control,” which is why dealing with it in the monument focuses more on response than prevention. Yet with invasive species, prevention is always the goal. And when you get a glimpse of the unique place that is Papahānaumokuākea Marine National Monument, it is not hard to understand the lengths being taken to protect it.


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