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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Detecting Change in a Changing World: 25 Years After the Exxon Valdez Oil Spill

Life between high and low tide along the Alaskan coast is literally rough and tumble.

The marine animals and plants living there have to deal with both crashing sea waves at high tide and the drying heat of the sun at low tide. Such a life can be up and down, boom and bust, as favorable conditions come and go quickly and marine animals and plants are forced to react and repopulate just as quickly.

But what happens when oil from the tanker Exxon Valdez enters this dynamic picture—and 25 years later, still hasn’t completely left? What happens when bigger changes to the ocean and global climate begin arriving in these waters already in flux?

Telling the Difference

Two people wearing chest waders sift for marine life in shallow rocky waters.

In 2011 NOAA marine biologist Gary Shigenaka (right) sifts through the sediments of Alaska’s Lower Herring Bay, looking for the tiny marine life that live there. (Photo by Gerry Sanger/Sound Ecosystem Adventures)

In the 25 years since the Exxon Valdez oil spill hit Alaska’s Prince William Sound, NOAA scientists, including marine biologist Gary Shigenaka and ecologist Alan Mearns, have been studying the impacts of the spill and cleanup measures on these animals and plants in rocky tidal waters.

Their experiments and monitoring over the long term revealed a high degree of natural variability in these communities that was unrelated to the oil spill. They saw large changes in, for example, numbers of mussels, seaweeds, and barnacles from year to year even in areas known to be unaffected by the oil spill.

This translated into a major challenge. How do scientists tell the difference between shifts in marine communities due to natural variability and those changes caused by the oil spill?

Several key themes emerged from NOAA’s long-term monitoring and subsequent experimental research:

  • impact. How do we measure it?
  • recovery. How do we define it?
  • variability. How do we account for it?
  • subtle connection to large-scale oceanic influences. How do we recognize it?

What NOAA has learned from these themes informs our understanding of oil spill response and cleanup, as well as of ecosystems on a larger scale. None of this, however, would have been apparent without the long-term monitoring effort. This is an important lesson learned from the Exxon Valdez experience: that monitoring and research, often viewed as an unnecessary luxury in the context of a large oil spill response, are useful, even essential, for framing the scientific and practical lessons learned.

Remote Possibilities

As NOAA looks ahead to the future—and with the Gulf of Mexico’s Deepwater Horizon oil spill in our recent past—we can incorporate and apply lessons of the Exxon Valdez long-term program into how we will support response decisions and define impact and recovery.

The Arctic is a region of intense interest and scrutiny. Climate change is opening previously inaccessible waters and dramatically shifting what scientists previously considered “normal” environmental conditions. This is allowing new oil production and increased maritime traffic through Arctic waters, increasing the risk of oil spills in remote and changing environments.

If and when something bad happens in the Arctic, how do scientists determine the impact and what recovery means, if our reference point is a rapidly moving target? What is our model habitat for restoring one area impacted by oil when the “unimpacted” reference areas are undergoing their own major changes?

Illustrated infographic showing timeline of ecological recovery after the Exxon Valdez oil spill.

Tracking the progress of recovery for marine life and habitats following the Exxon Valdez oil spill is no easy task. Even today, not all of the species have recovered or we don’t have enough information to know. (NOAA) Click to enlarge.

Listening in

NOAA marine biologist Gary Shigenaka explores these questions as he reflects on the 25 years since the Exxon Valdez oil spill in the following Making Waves podcast from the National Ocean Service:

[NARRATOR] This all points back at what Gary says is the main take-away lesson after 25 years of studying the aftermath of this spill: the natural environment in Alaska and in the Arctic are rapidly changing. If we don’t understand that background change, then it’s really hard to say if an area has recovered or not after a big oil spill.

[GARY SHIGENAKA] “I think we need to really keep in mind that maybe our prior notions of recovery as returning to some pre-spill or absolute control condition may be outmoded. We need to really overlay that with the dynamic changes that are occurring for whatever reason and adjust our assessments and definitions accordingly. I don’t have the answers for the best way to do that. We’ve gotten some ideas from the work that we’ve done, but I think that as those changes begin to accelerate and become much more marked, then it’s going to be harder to do.”

 

Read a report by Gary Shigenaka summarizing information about the Exxon Valdez oil spill and response along with NOAA’s role and research on its recovery over the past 25 years.


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Where Are the Pacific Garbage Patches Located?

Microplastics in sand.

Microplastics, small plastics less than 5 millimeters long, are an increasingly common type of marine debris found in the water column (including the “garbage patches”) and on shorelines around the world. Based on research to date, most commonly used plastics do not fully degrade in the ocean and instead break down into smaller and smaller pieces. (NOAA Marine Debris Program)

The Pacific Ocean is massive. It’s the world’s largest and deepest ocean, and if you gathered up all of the Earth’s continents, these land masses would fit into the Pacific basin with a space the size of Africa to spare.

While the Pacific Ocean holds more than half of the planet’s free water, it also unfortunately holds a lot of the planet’s garbage (much of it plastic). But that trash isn’t spread evenly across the Pacific Ocean; a great deal of it ends up suspended in what are commonly referred to as “garbage patches.”

A combination of oceanic and atmospheric forces causes trash, free-floating sea life (for example, algae, plankton, and seaweed), and a variety of other things to collect in concentrations in certain parts of the ocean. In the Pacific Ocean, there are actually a few “Pacific garbage patches” of varying sizes as well as other locations where marine debris is known to accumulate.

The Eastern Pacific Garbage Patch (aka “Great Pacific Garbage Patch”)

In most cases when people talk about the “Great Pacific Garbage Patch,” they are referring to the Eastern Pacific garbage patch. This is located in a constantly moving and changing swirl of water roughly midway between Hawaii and California, in an atmospheric area known as the North Pacific Subtropical High.

NOAA National Weather Service meteorologist Ted Buehner describes the North Pacific High as involving “a broad area of sinking air resulting in higher atmospheric pressure, drier warmer temperatures and generally fair weather (as a result of the sinking air).”

This high pressure area remains in a semi-permanent state, affecting the movement of the ocean below. “Winds with high pressure tend to be light(er) and blow clockwise in the northern hemisphere out over the open ocean,” according to Buehner.

As a result, plastic and other debris floating at sea tend to get swept into the calm inner area of the North Pacific High, where the debris becomes trapped by oceanic and atmospheric forces and builds up at higher concentrations than surrounding waters. Over time, this has earned the area the nickname “garbage patch”—although the exact content, size, and location of the associated marine debris accumulations are still difficult to pin down.

Map of ocean currents, features, and areas of marine debris accumulation (including

This map is an oversimplification of ocean currents, features, and areas of marine debris accumulation (including “garbage patches”) in the Pacific Ocean. There are numerous factors that affect the location, size, and strength of all of these features throughout the year, including seasonality and El Nino/La Nina. (NOAA Marine Debris Program)

The Western Pacific Garbage Patch

On the opposite side of the Pacific Ocean, there is another so-called “garbage patch,” or area of marine debris buildup, off the southeast coast of Japan. This is the lesser known and studied, Western Pacific garbage patch. Southeast of the Kuroshio Extension (ocean current), researchers believe that this garbage patch is a small “recirculation gyre,” an area of clockwise-rotating water, much like an ocean eddy (Howell et al., 2012).

North Pacific Subtropical Convergence Zone

While not called a “garbage patch,” the North Pacific Subtropical Convergence Zone is another place in the Pacific Ocean where researchers have documented concentrations of marine debris. A combination of oceanic and atmospheric forces create this convergence zone, which is positioned north of the Hawaiian Islands but moves seasonally and dips even farther south toward Hawaii during El Niño years (Morishige et al., 2007, Pichel et al., 2007). The North Pacific Convergence Zone is an area where many open-water marine species live, feed, or migrate and where debris has been known to accumulate (Young et al. 2009). Hawaii’s islands and atolls end up catching a notable amount of marine debris as a result of this zone dipping southward closer to the archipelago (Donohue et al. 2001, Pichel et al., 2007).

But the Pacific Ocean isn’t the only ocean with marine debris troubles. Trash from humans is found in every ocean, from the Arctic (Bergmann and Klages, 2012) to the Antarctic (Eriksson et al., 2013), and similar oceanic processes form high-concentration areas where debris gathers in the Atlantic Ocean and elsewhere.

You can help keep trash from becoming marine debris by:

Carey Morishige, Pacific Islands regional coordinator for the NOAA Marine Debris Program, also contributed to this post.

Literature Cited

Bergmann, M. and M. Klages. 2012. Increase of litter at the Arctic deep-sea observatory HAUSGARTEN. Marine Pollution Bulletin, 64: 2734-2741.

Donohue, M.J., R.C. Boland, C.M. Sramek, and G.A Antonelis. 2001. Derelict fishing gear in the Northwestern Hawaiian Islands: diving surveys and debris removal in 1999 confirm threat to coral reef ecosystems. Marine Pollution Bulletin, 42 (12): 1301-1312.

Eriksson, C., H. Burton, S. Fitch, M. Schulz, and J. van den Hoff. 2013. Daily accumulation rates of marine debris on sub-Antarctic island beaches. Marine Pollution Bulletin, 66: 199-208.

Howell, E., S. Bograd, C. Morishige, M. Seki, and J. Polovina. 2012. On North Pacific circulation and associated marine debris concentration. Marine Pollution Bulletin, 65: 16-22.

Morishige, C., M. Donohue, E. Flint, C. Swenson, and C. Woolaway. 2007. Factors affecting marine debris deposition at French Frigate Shoals, Northwestern Hawaiian Islands Marine National Monument, 1990-2002. Marine Pollution Bulletin, 54: 1162-1169.

Pichel, W.G., J.H. Churnside, T.S. Veenstra, D.G. Foley, K.S. Friedman, R.E. Brainard, J.B. Nicoll, Q. Zheng and P. Clement-Colon. 2007. Marine debris collects within the North Pacific Subtropical Convergence Zone [PDF]. Marine Pollution Bulletin, 54: 1207-1211.

Young L. C., C. Vanderlip, D. C. Duffy, V. Afanasyev, and S. A. Shaffer. 2009. Bringing home the trash: do colony-based differences in foraging distribution lead to increased plastic ingestion in Laysan albatrosses? PLoS ONE 4 (10).


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Post Hurricane Sandy, NOAA Aids Hazardous Spill Cleanup in New Jersey and New York

Oil sheen is visible on the waters of Arthur Kill on the border of New Jersey and New York in the wake of Hurricane Sandy.

Oil sheen is visible on the waters of Arthur Kill on the border of New Jersey and New York in the wake of Hurricane Sandy. (NOAA)

[UPDATED NOVEMBER 6, 2012] Hurricane Sandy’s extreme weather conditions—80 to 90 mph winds and sea levels more than 14 feet above normal—spread oil, hazardous materials, and debris across waterways and industrial port areas along the Mid Atlantic. NOAA’s Office of Response and Restoration is working with the U.S. Coast Guard and affected facilities to reduce the impacts of this pollution in coastal New York and New Jersey.

We have several Scientific Support Coordinators and information management specialists on scene at the incident command post on Staten Island, N.Y.

Since the pollution response began, we have been dispatching observers in helicopters with the Coast Guard to survey the resulting oil sheens on the water surface in Arthur Kill, N.J./N.Y. This is in support of the response to a significant spill at the Motiva Refinery in Sewaren, N.J., as well as for the cleanup and assessment of several small spills of diesel fuel, biodiesel, and various other petroleum products scattered throughout northern New Jersey’s refinery areas.

One of the challenges facing communities after a devastating weather event is information management. One tool we have developed for this purpose is ERMA, an online mapping tool which integrates and synthesizes various types of environmental, geographic, and operational data. This provides a central information hub for all individuals involved in an incident, improves communication and coordination among responders, and supplies resource managers with the information necessary to make faster and better informed decisions.

ERMA has now been adopted as the official common operational platform for the Hurricane Sandy pollution response, and we have sent additional GIS specialists to the command post.

Species and Habitats at Risk

The most sensitive habitats in the area are salt marshes, which are often highly productive and are important wildlife habitat and nursery areas for fish and shellfish. Though thin sheens contain little oil, wind and high water levels after the storm could push the diesel deep into the marsh, where it could persist and contaminate sediments. Because marshes are damaged easily during cleanup operations, spill response actions will have to take into account all of these considerations.

In addition, diesel spills can kill the many small invertebrates at the base of the food chain which live in tidal flats and salt marshes if they are exposed to a high enough concentration. Resident marsh fishes, which include bay anchovy, killifish, and silversides, are the fish most at risk because they are the least mobile and occupy shallow habitats. Many species of heron nest in the nearby inland marshes, some of the last remaining marshlands in Staten Island. Swimming and diving birds, such as Canada geese and cormorants, are also vulnerable to having their feathers coated by the floating oil, and all waterfowl have the potential to consume oil while feeding.

Based on the risks to species and habitats from both oil and cleanup, we weigh the science carefully before making spill response recommendations to the Coast Guard.

Tracking the Spilled Oil

Responders face an oily debris field in Sheepshead Bay, N.Y., after Hurricane Sandy. Nov. 2, 2012.

Responders face an oily debris field in Sheepshead Bay, N.Y., after Hurricane Sandy. Nov. 2, 2012. (U.S. Coast Guard)

Because no two oils are alike, we train aerial observers to evaluate the character and extent of oil spilled on the water. NOAA performs these aerial surveys, or overflights, of spilled oil like in Arthur Kill to determine the status of the oil’s source and to track where wind and waves are moving spilled oil while also weathering it. The movement of wind and waves, along with sunlight, works to break down oil into its chemical components. This changes the appearance, size, and location of oil, and in return, can change how animals and plants interact with the oil.

When spilled on water, diesel oil spreads very quickly to a thin film. However, diesel has high levels of toxic components which dissolve fairly readily into the water column, posing threats to the organisms living there. Biodiesel can coat animals that come into contact with it, but it breaks down up to four times more quickly than conventional diesel. At the same time, this biodegradation could cause potential fish kills by using up large amounts of oxygen in the water, especially in shallow areas.

Look for photos, maps, and updates on pollution-related response efforts at IncidentNews.

Check the Superstorm Sandy CrisisMap for aggregated information from NOAA, FEMA, and other sources on weather alerts and observations; storm surge and flood water data; aerial damage assessment imagery; and the locations of power outages, food and gas in New Jersey, and emergency shelters.


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What Happens After Abandoning Ship

Twenty three years after running aground on a reef in Alaska and causing one of the largest spills in U.S. history, the tanker Exxon Valdez is back in the news—this time to keep it from being intentionally grounded on a beach in India.

The Indian Supreme Court has ruled that the Exxon Valdez (now called the Oriental Nicety) cannot be grounded and cut apart on the shores of Gujarat until it can be cleaned of residual oils and other contaminants.

Workers scrap ships for parts and metal on a beach in Bhatiari, Chittagong, Bangladesh.

Workers scrap ships for parts and metal (“ship breaking”) on a beach in Bhatiari, Chittagong, Bangladesh. Credit: Naquib Hossain, Creative Commons License: Attribution-ShareAlike 2.0).

What’s known as “ship breaking” is a dirty business, and many of the world’s tired and obsolete vessels end up being grounded on beaches in India, Bangladesh, and Pakistan and cut apart for scrap steel.

In recent years the business of ship scrapping has become a major health and environmental concern. Many ship breaking yards in these developing countries have little or no safety equipment or environmental protections, and toxic materials from these ships, including oils, heavy metals, and asbestos, escape into the environment.

A derelict vessel grounded on a coal reef in Samoa.

A rusted-out derelict vessel still sits grounded on a coal reef in Samoa. (NOAA/Doug Helton)

Obsolete vessels and ship scrapping can also be a problem here in the U.S. Last year, the 431-foot S/S Davy Crockett made the news down on the Columbia River near Vancouver, Wash.

Mysterious oil sheens on the river were traced upriver to the former Navy Liberty ship that had begun leaking oil due to improper and unpermitted salvage operations.

Next week I will be at the Clean Pacific Conference in Long Beach, Calif., and presenting information on the challenges of dealing with abandoned and derelict vessels in the U.S. I know that the Davy Crockett and the issues it raised will come up.

Vessels are abandoned for all sorts of reasons, including storms (particularly hurricanes/typhoons which may damage large numbers of boats), community-wide economic stress or change (e.g., declining commercial fishing industries), and financial or legal issues of individual owners.  The high cost of proper vessel disposal can lead some folks to just walk away.

Hopefully we can help improve how we respond to these vessels and increase prevention programs to prevent abandonment. If you are interested in this issue, there is more information on NOAA’s Abandoned Vessel Program.