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


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In Oregon, an Innovative Approach to Building Riverfront Property for Fish and Wildlife

This is a post by Robert Neely of NOAA’s Office of Response Restoration.

Something interesting is happening on the southern tip of Sauvie Island, located on Oregon’s Willamette River, a few miles downstream from the heart of Portland. Construction is once again underway along the river’s edge in an urban area where riverfront property typically is prized as a location for luxury housing, industrial activities, and maritime commerce. But this time, something is different.

This project will not produce a waterfront condominium complex, industrial facility, or marina. And as much as it may look like a typical construction project today, the results of all this activity will look quite different from much of what currently exists along the shores of the lower Willamette River from Portland to the Columbia River.

Indeed, when the dust settles, the site will be transformed into a home and resting place for non-human residents and visitors. Of course, I’m not referring to alien life forms, but rather to the fish, birds, mammals, and other organisms that have existed in and around the Willamette River since long before humans set up home and shop here. Yet in the last century, humans have substantially altered the river and surrounding lands, and high-quality habitat is now a scarce commodity for many stressed critters that require it for their survival.

On the site of a former lumber mill, the Alder Creek Restoration Project is the first habitat restoration project [PDF] that will be implemented specifically to benefit fish and wildlife affected by contamination in the Portland Harbor Superfund Site. The project, managed by a habitat development company called Wildlands, will provide habitat for salmon, lamprey, mink, bald eagle, osprey, and other native fish and wildlife living in Portland Harbor.

Mink at a river's edge.

The Alder Creek Restoration Project will benefit Chinook salmon, mink, and other fish and wildlife living in Portland Harbor. (Roy W. Lowe)

Habitat will be restored by removing buildings and fill from the floodplain, reshaping the riverbanks, and planting native trees and shrubs. The project will create shallow water habitat to provide resting and feeding areas for young salmon and lamprey and foraging for birds. In addition, the construction at Alder Creek will restore beaches and wetlands to provide access to water and food for mink and forests to provide shelter and nesting opportunities for native birds.

Driving this project is a Natural Resource Damage Assessment conducted by the Portland Harbor Natural Resource Trustee Council to quantify natural resource losses resulting from industrial contamination of the river with the toxic compounds PCBs, the pesticide DDT, oil compounds known as PAHs, and other hazardous substances. The services, or benefits from nature, provided by the Alder Creek Restoration Project—such as healthy habitat, clean water, and cultural value—will help make up for the natural resources that were lost over time because of contamination.

Young Chinook salmon on river bottom.

Fish and wildlife species targeted for restoration include salmon (such as the juvenile Chinook salmon pictured here), lamprey, sturgeon, bald eagle, osprey, spotted sandpiper, and mink. (U.S. Fish and Wildlife Service)

Wildlands purchased the land in order to create and implement an early restoration project. This “up-front” approach to restoration allows for earlier implementation of projects that provide restored habitat to injured species sooner, placing those species on a trajectory toward recovery. The service credits—ecological and otherwise—that will be generated by this new habitat will be available for purchase by parties that have liability for the environmental and cultural losses calculated in the damage assessment.

Thus when a party reaches an agreement with the Trustee Council regarding the amount of their liability, they can resolve it by purchasing restoration credits from Wildlands. And Wildlands, as the seller of restoration credits, recoups the financial investment it made to build the project. Finally, and most importantly, a substantial piece of land with tremendous potential value for the fish, birds, and other wildlife of the lower Willamette River has been locked in as high-quality habitat and thus protected from future development for other, less ecologically friendly purposes.

Robert NeelyRobert Neely is an environmental scientist with the National Oceanic and Atmospheric Administration’s Office of Response and Restoration. He has experience in ocean and coastal management, brownfields revitalization, Ecological Risk Assessment, and Natural Resource Damage Assessment. He started with NOAA in 1998 and has worked for the agency in Charleston, South Carolina; Washington, DC; New Bedford, Massachusetts; and Seattle, Washington, where he lives with his wife and daughter. He’s been working with his co-trustees at Portland Harbor since 2005.


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Two Unlikely Neighbors, Orphans and Industry, Share a Past Along the Delaware River

Sign in a grassy field, in front of an old brick building.

An EPA sign marking the Metal Bank Superfund Site stands near the old St. Vincent’s Orphanage building. (EPA)

When NOAA environmental scientist Alyce Fritz talks about her first visit to the Metal Bank Superfund Site back in 1986, she always mentions the orphanage next door. St. Vincent’s Orphans Asylum, as it was named when it was opened by the Catholic Archdiocese of Philadelphia in 1857, is separated from the Metal Bank site by a stormwater outfall that drains into the Delaware River just north of the former orphanage.

The Metal Bank Superfund Site and St. Vincent’s are located several miles north of the center of Philadelphia, Pennsylvania, on the banks of the Delaware River in an industrial district that is part of the historic Tacony neighborhood. Located on 29 acres along the river, St. Vincent’s looks like a beautiful old park. What Fritz remembers clearly on that first visit was the children’s playground equipment placed near the river’s edge.

Large brick building with St. Vincint's over the door.

St. Vincent’s, as it appears today on the Delaware River in the Tacony neighborhood of Philadelphia.

On the adjacent 10 acre Metal Bank site, a company called Metal Bank of America, Inc., owned and operated a salvage facility where scrap metal and electric transformers were recycled for over 60 years. Part of the recycling process used by Metal Bank of America, Inc. involved draining oil—loaded with toxic compounds including PCBs—from the used transformers to reclaim copper parts. PCBs are considered a probable cause of cancer in humans and are harmful to clams and fish found in the mudflats and river next to the site.

In the 1970s the U.S. Coast Guard discovered oil releases in the Delaware River and traced them back to the site. Throughout the 1980s, the Metal Bank site’s owners used an oil recovery system to clear the groundwater of PCB-laced oil. However, oil continued to seep from an underground tank at the site. As a result, PCBs and other hazardous substances were left in the soil, groundwater, and river bed sediments at the Metal Bank site and adjacent to St. Vincent’s.

In 1983 the Metal Bank site was placed on the National Priorities List (the Superfund program) and slated for federal cleanup. During the course of the federal cleanup process, various parties were identified as being liable for the contamination at the site, including a number of utility companies that transported their used electrical transformers to the Metal Bank site for disposal or otherwise arranged to dispose of their used electrical transformers at the Metal Bank site.

Federal and local agencies collaborated on a design for cleanup of multiple contaminants of concern at the Metal Bank site. Found in the soil, sediment, groundwater, and surface water, these contaminants included but were not limited to:

  • PCBs.
  • polynuclear aromatic hydrocarbons (a toxic component of oil).
  • semi-volatile organic compounds.
  • pesticides.
  • metals.

The cleanup, which began in 2008, included excavating soils and river sediments contaminated with PCBs, capping some areas of river sediment, installing a retaining wall near the river, and removing an old transformer oil storage tank. Most of this work was completed in 2010.

Panorama of Metal Bank Superfund Site from the top of steps by the river to the mudflats in 1991. The view is looking south on the Delaware River past St. Vincent’s property. (NOAA) A view of the outflow where water runs into the Delaware River to the south of the Metal Bank site in 2013. (NOAA) A riprap sampling station near an oil slick in 1993 in front of the Metal Bank site. (NOAA) A view of the Delaware River across the mudflats on the Metal Bank Site. (EPA)

Panorama of Metal Bank Superfund Site from the top of steps by the river to the mudflats in 1991. The view is looking south on the Delaware River past St. Vincent’s property. (NOAA) A view of the outflow where water runs into the Delaware River to the south of the Metal Bank site in 2013. (NOAA) A riprap sampling station near an oil slick in 1993 in front of the Metal Bank site. (NOAA) A view of the Delaware River across the mudflats on the Metal Bank Site. (EPA)

As part of the required 5-year review period, monitoring of the Metal Bank site continues. This is to ensure the cleanup is still protecting human health and the environment, including endangered Atlantic Sturgeon and Shortnose Sturgeon. Through successful coordination among the EPA, other federal and state agencies, and some of the potentially responsible parties (PRPs) during the Superfund process, the cleanup has reduced the threat to natural resources in the river and enhanced the recovery of the habitat along the site and St. Vincent’s property.

Over the years, the role of St. Vincent’s has evolved too, from serving as a long-term home for orphans toward one of providing short-term shelter and care to abused and neglected children. Prior to the early 1990s, children who came to St. Vincent’s spent a significant part of their childhood as residents of the institution. In a 1992 article in the Philadelphia Daily News, Sister Kathleen Reilly explained that the children currently cared for by St. Vincent’s range in age from two to 12 years of age and are placed at the home temporarily through an arrangement between the City of Philadelphia Department of Human Services and Catholic Social Services. Today St. Vincent’s serves young people mostly through day programs. One thing hasn’t changed though—the lush grounds along the river are still beautiful.

Playground swings at St. Vincent's. Statue of St. Vincent with a child in front of large brick building. Elaborate locked iron gate with a cross. Pavilion with trees and river view.

From top left: A recent photo of part of the play area behind St. Vincent’s on the grounds facing the Delaware River. (NOAA) An old photo of a statue in front of St. Vincent’s Orphan Asylum, as it was originally named. (U.S. Library of Congress) The main building of the historic institution in Northeast Philadelphia that first opened its gates in 1857 as St. Vincent’s Orphans Asylum. Photo was taken in 2013. (NOAA) An old photo of a pavilion in the recreational area behind St. Vincent’s main building. The Delaware River and playground equipment is visible in the background. (U.S. Library of Congress)

The federal and state co-trustees for the ongoing Natural Resource Damage Assessment at the Metal Bank site include NOAA’s Damage Assessment, Remediation, and Restoration Program; the U.S. Fish and Wildlife Service; and multiple Pennsylvania state agencies. Collectively, the trustees are working together to further engage with the potentially responsible parties and build upon what has been accomplished at the site by the cleanup.

The trustees have invited the potentially responsible parties to join them in a cooperative effort to improve habitat for the injured natural resources (such as habitat along the river and wetlands) that support the clams, fish, and birds using the Delaware River. In addition, there is the potential for a trail to be routed through the property to a scenic view of St. Vincent’s and the river (an area which is now safe for recreational use). The trustees hope that the natural resources at the Metal Bank site can evolve to become a vibrant part of the historic Tacony neighborhood once again too.


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As Oil Sands Production Rises, What Should We Expect at Diluted Bitumen (Dilbit) Spills?

Pipeline dug up for an oil spill cleanup next to a creek.

This area is where the Enbridge pipeline leaked nearly a million gallons of diluted bitumen (dilbit), a tar sands oil product, into wetlands, Talmadge Creek, and roughly 40 miles of Michigan’s Kalamazoo River in 2010. (U.S. Environmental Protection Agency)

I’ve seen a lot of firsts in the past four years.

During that time, I have been investigating the environmental impacts, through the Natural Resource Damage Assessment process, of the Enbridge pipeline spill in Michigan. In late summer of 2010, a break in an underground pipeline spilled approximately 1 million gallons of diluted bitumen into a wetland, a creek, and the Kalamazoo River. Diluted bitumen (“dilbit”) is thick, heavy crude oil from the Alberta tar sands (also known as oil sands), which is mixed with a thinner type of oil (the diluent) to allow it to flow through a pipeline.

A Whole New Experience

This was my first and NOAA’s first major experience with damage assessment for a dilbit spill, and was also a first for nearly everyone working on the cleanup and damage assessment. Dilbit production and shipping is increasing. As a result, NOAA and our colleagues in the field of spill response and damage assessment are interested in learning more about dilbit:

  • How does it behave when spilled into rivers or the ocean?
  • What kinds of effects does it have on animals, plants, and habitats?
  • Is it similar to other types of oil we’re more familiar with, or does it have unique properties?

While it’s just one case study, the Enbridge oil spill can help us answer some of those questions. My NOAA colleague Robert Haddad and I recently presented a scientific paper on this case study at Environment Canada’s Arctic and Marine Oil Spill Program conference.

In addition, the Canadian government and oil pipeline industry researchers Witt O’Brien’s, Polaris, and Western Canada Marine Response Corporation [PDF] and SL Ross [PDF] have been studying dilbit behavior as background research related to several proposed dilbit pipeline projects in the United States and Canada. Those experiments, along with the Enbridge spill case study, currently make up the state of the science on dilbit behavior and ecological impacts.

How Is Diluted Bitumen Different from Other Heavy Oils?

Dilbit is in the range of other dense, heavy oils, with a density of 920 to 940 kg/m3, which is close to the density of freshwater (1,000 kg/m3). (In general when something is denser than water, it will sink. If it is less dense, it will float.) Many experts have analyzed the behavior of heavy oils in the environment and observed that if oil sinks below the surface of the water, it becomes much harder to detect and recover. One example of how difficult this can be comes from a barge spill in the Gulf of Mexico, which left thick oil coating the bottom of the ocean.

What makes dilbit different from many other heavy oils, though, is that it includes diluent. Dilbit is composed of about 70 percent bitumen, consisting of very large, heavy molecules, and 30 percent diluent, consisting of very small, light molecules, which can evaporate much more easily than heavy ones. Other heavy oils typically have almost no light components at all. Therefore, we would expect evaporation to occur differently for dilbit compared to other heavy oils.

Environment Canada confirmed this to be the case. About four to five times as much of the dilbits evaporated compared to intermediate fuel oil (a heavy oil with no diluent), and the evaporation occurred much faster for dilbit than for intermediate fuel oil in their study. Evaporation transports toxic components of the dilbit into the air, creating a short-term exposure hazard for spill responders and assessment scientists at the site of the spill, which was the case at the 2010 Enbridge spill.

Graph of evaporation rates over time of two diluted bitumen oils and another heavy oil.

An Environment Canada study found that two types of diluted bitumen (dilbits), Access Western Blend (AWB) and Cold Lake Blend (CLB), evaporated more quickly and to a greater extent than intermediate fuel oil (IFO). The two dilbits are shown on the left and the conventional heavy oil, IFO, on the right. (Environment Canada)

Since the light molecules evaporate after dilbit spills, the leftover residue is even denser than what was spilled initially. Environment Canada, Witt O’Brien’s/Polaris/WCMRC, and SL Ross measured the increase in dilbit density over time as it weathered, finding dilbit density increased over time and eventually reached approximately the same density as freshwater.

These studies also found most of the increase in density takes place in the first day or two. What this tells us is that the early hours and days of a dilbit spill are extremely important, and there is only a short window of time before the oil becomes heavier and may become harder to clean up as it sinks below the water surface.

Unfortunately, there can be substantial confusion in the early hours and days of a spill. Was the spilled material dilbit or conventional heavy crude oil? Universal definitions do not exist for these oil product categories. Different entities sometimes categorize the same products differently. Because of these discrepancies, spill responders and scientists evaluating environmental impacts may get conflicting or hard-to-interpret information in the first few days following a spill.

Lessons from the Enbridge Oil Spill

Initially at the Enbridge oil spill, responders used traditional methods to clean up oil floating on the river’s surface, such as booms, skimmers, and vacuum equipment (see statistics on recovered oil in EPA’s Situation Reports [PDF]).

After responders discovered the dilbit had sunk to the sediment at the river’s bottom, they developed a variety of tactics to collect the oil: spraying the sediments with water, dragging chains through the sediments, agitating sediments by hand with a rake, and driving back and forth with a tracked vehicle to stir up the sediments and release oil trapped in the mud.

These tactics resulted in submerged oil working its way back up to the water surface, where it could then be collected using sorbent materials to mop up the oily sheen.

While these tactics removed some oil from the environment, they might also cause collateral damage, so the Natural Resource Damage Assessment trustees assessed impacts from the cleanup tactics as well as from the oil itself. This case is still ongoing, and trustees’ assessment of those impacts will be described in a Damage Assessment and Restoration Plan after the assessment is complete.

A hand holds a crushed mussel.

A freshwater mussel found crushed in an area of the Kalamazoo River with heavy cleanup traffic following the 2010 Enbridge oil spill. (Enbridge Natural Resource Damage Assessment Trustee Council)

For now, we can learn from the Enbridge spill and help predict some potential environmental impacts of future dilbit spills. We can predict that dilbit will weather (undergo physical and chemical changes) rapidly, becoming very dense and possibly sinking in a matter of days. If the dilbit reaches the sediment bed, it can be very difficult to get it out, and bringing in responders and heavy equipment to recover the oil from the sediments can injure the plants and animals living there.

To plan the cleanup and response and predict the impacts of future dilbit spills, we need more information on dilbit toxicity and on how quickly plants and animals can recover from disturbance. Knowing this information will help us balance the potential impacts of cleanup with the short- and long-term effects of leaving the sunken dilbit in place.


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A River Reborn: Restoring Salmon Habitat along Seattle’s Duwamish River

Industrial river with part of a boat in the view.

Cutting through south Seattle, the Duwamish River is still very much an industrial river. (NOAA)

Just south of Seattle, the airplane manufacturer Boeing Company has created one of the largest habitat restoration projects on the Lower Duwamish River. Boeing worked with NOAA and our partners under a Natural Resource Damage Assessment to restore habitat for fish, shorebirds, and wildlife harmed by historical industrial activities on this heavily used urban river. We documented and celebrated this work in a short video.

What Kind of Restoration?

In this video, you can learn about the restoration techniques used in the project and how they will benefit the communities of people, fish, and wildlife of the Duwamish River. The restoration project included activities such as:

  • Reshaping the shoreline and adding 170,000 native plants and large woody debris, which provide areas where young salmon can seek refuge from predators in the river.
  • Creating 2 acres of wetlands to create a resting area for migrating salmon.
  • Transforming more than a half mile of former industrial waterfront back into natural shoreline.

Watch the video:

Why Does this River Need Restoring?

In 1913, the U.S. Army Corps of Engineers excavated and straightened the Duwamish River to expand Seattle’s commercial navigation, removing more than 20 million cubic yards of mud and sand and opening the area to heavy industry. But development on this waterway stretches back to the 1870s.

Ninety-seven percent of the original habitat for salmon—including marsh, mudflats, and toppled trees along multiple meandering channels— was lost when they transformed a 9-mile estuary into a 5-mile industrial channel.

As damaged and polluted as the Lower Duwamish Waterway is today, the habitat here is crucial to ensuring the survival and recovery of threatened fish species, including the Puget Sound Chinook and Puget Sound Steelhead. These young fish have to spend time in this part of the Duwamish River, which is a Superfund Site, as they transition from the river’s freshwater to the saltwater of the Puget Sound and Pacific Ocean. Creating more welcoming habitat for these fish gives them places to find food and escape from predators.

Fortunately, this restored waterfront outside of a former Boeing plant will be maintained for all time, and further cleanup and restoration of the river is in various stages as well.

UPDATE 6/17/2014: On June 17, 2014, Boeing hosted a celebration on the newly restored banks of the Lower Duwamish River to recognize the partners who helped make the restoration a reality. Speakers at the event included NOAA, Boeing, the Muckleshoot Tribe, and a local community group. This also gave us the opportunity to share the video “A River Reborn,” which was well received.


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How Will You Celebrate World Ocean Day?

Red-footed booby landing near edge of ocean atoll.

Red-footed booby at the Three Sisters at Pearl and Hermes Atoll in the Papahanaumokuakea Marine National Monument. (NOAA)

World Ocean Day is June 8, and we’re only a month away. What will you do to celebrate and protect that big blue body of water that sustains our planet?

We have a few ideas to get you ready:

Look for even more ways to keep the ocean healthy and free of pollution, a small way of saying thanks for everything the ocean does for us.


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Watch Art Explain What Kind of Habitat Young Salmon Need to Thrive

Illustration from video of two salmon swimming by tree roots.What do young salmon need to grow into the kind of big, healthy adult salmon enjoyed by people as well as bears, seals, and other wildlife? A recent collaboration between NOAA Fisheries and the Pacific Northwest College of Arts makes the answer come to life in a beautiful animation by artists Beryl Allee and John Summerson.

Watch the intersection of art and science as we follow young salmon happily swimming through the cool, shallow waters along a shore. We see the bits of wood, tangled tree roots, and scattered rocks that provide these fish with both insects to eat and protection from predators.

But what happens when a home or business shows up along the water’s edge? How do people remake the shoreline? What kind of environment does this create for those same little salmon?

NOAA partnered with the Pacific Northwest College of Arts to create this moving and educational tool to raise awareness among waterfront landowners and the general public about how the decisions we make affect endangered salmon. In particular, NOAA wanted to address the practice of “armoring,” or using physical structures such as rocks and concrete to protect shorelines from coastal erosion. As we can see in the animation, armored shorelines do not make for happy, healthy young salmon.

Illustration from animation of a sad fish and an armored shoreline.

However, alternatives to armoring shorelines with hard materials are emerging. They include using plants and organic materials to stabilize the shores while also preserving or creating the kind of habitat young salmon need.

Creating better habitat for fish is often the goal of NOAA’s Damage Assessment, Remediation, and Restoration Program (DARRP). When we determine that fish were harmed after an oil spill or hazardous chemical release, we, with the help of a range of partners and the public, identify and implement restoration projects to make up for this harm.

Take a look at a few examples in which we built better habitat for salmon:

Beaver Creek, Oregon

A tanker truck carrying gasoline overturned on scenic Highway 26 through central Oregon in 1999, spilling 5,000 gallons of gasoline into Beaver Butte Creek and impacting steelhead trout and Chinook salmon. Working with the Confederated Tribes of the Warm Springs Reservation of Oregon and other partners, we have helped implement five restoration projects. They range from adding large wood to stream banks to provide fish habitat to installing two beaver dam–mimicking structures to improve water quality.

White River, Washington

In 2006 a system failure sent 18,000 gallons of diesel into creeks and wetlands important to endangered Chinook salmon around Washington’s White River. To improve and expand habitat for these salmon, NOAA and our partners removed roadfill and added large pieces of wood (“logjams”) along the edges of the nearby Greenwater River. This restoration project will help slow and redirect the river’s straight, fast-moving currents, creating deep pools for salmon to feed and hide from predators and allowing some of the river water to overflow into slower, shallower tributaries perfect for spawning salmon.

Adak, Alaska

On the remote island of Adak in Alaska’s Aleutian Islands, a tanker overfilled an underground storage tank in 2010. This resulted in up to 142,800 gallons of diesel eventually flowing into the nearby salmon stream, Helmet Creek. Pink salmon and Dolly Varden trout were particularly affected. In 2013 NOAA and our partners restored fish passage to the creek, improved habitat and water quality, made stream flow and channel improvements, and removed at least a dozen 55-gallon drums from the creek bed and banks.

You can also watch a video to learn how NOAA is restoring recreationally and commercially important fish through a variety of projects in the northeast United States.


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Little “Bugs” Can Spread Big Pollution Through Contaminated Rivers

This is a post by the NOAA Restoration Center’s Lauren Senkyr.

When we think of natural resources harmed by pesticides, toxic chemicals, and oil spills, most of us probably envision soaring birds or adorable river otters.  Some of us may consider creatures below the water’s surface, like the salmon and other fish that the more charismatic animals eat, and that we like to eat ourselves. But it’s rare that we spend much time imagining what contamination means for the smaller organisms that we don’t see, or can’t see without a microscope.

Mayfly aquatic insect on river bottom.

A mayfly, pictured above, is an important component in the diet of salmon and other fish. (NOAA)

The tiny creatures that live in the “benthos”—the mud, sand, and stones at the bottoms of rivers—are called benthic macroinvertebrates. Sometimes mistakenly called “bugs,” the benthic macroinvertebrate community actually includes a variety of animals like snails, clams, and worms, in addition to insects like mayflies, caddisflies, and midges. They play several important roles in an ecosystem. They help cycle and filter nutrients and they are a major food source for fish and other animals.

Though we don’t see them often, benthic macroinvertebrates play an extremely important role in river ecosystems. In polluted rivers, such as the lower 10 miles of the Willamette River in Portland, Oregon, these creatures serve as food web pathways for legacy contaminants like PCBs and DDT. Because benthic macroinvertebrates live and feed in close contact with contaminated muck, they are prone to accumulation of contaminants in their bodies.  They are, in turn, eaten by predators and it is in this way that contaminants move “up” through the food web to larger, more easily recognizable animals such as sturgeon, mink, and bald eagles.

Some of the ways contaminants can move through the food chain in the Willamette River.

Some of the ways contaminants can move through the food chain in the Willamette River. (Portland Harbor Trustee Council)

The image above depicts some of the pathways that contaminants follow as they move up through the food web in Oregon’s Portland Harbor. Benthic macroinvertebrates are at the bottom of the food web. They are eaten by larger animals, like salmon, sturgeon, and bass. Those fish are then eaten by birds (like osprey and eagle), mammals (like mink), and people.

An illustration showing how concentrations of the pesticide DDT biomagnify 10 million times as they move up the food chain from macroinvertebrates to fish to birds of prey.

An illustration showing how concentrations of the pesticide DDT biomagnify 10 million times as they move up the food chain from macroinvertebrates to fish to birds of prey. (U.S. Fish and Wildlife Service)

As PCB and DDT contamination makes its way up the food chain through these organisms, it is stored in their fat and biomagnified, meaning that the level of contamination you find in a large organism like an osprey is many times more than what you would find in a single water-dwelling insect. This is because an osprey eats many fish in its lifetime, and each of those fish eats many benthic macroinvertebrates.

Therefore, a relatively small amount of contamination in a single insect accumulates to a large amount of contamination in a bird or mammal that may have never eaten an insect directly.  The graphic to the right was developed by the U.S. Fish and Wildlife Service to illustrate how DDT concentrations biomagnify 10 million times as they move up the food chain.

Benthic macroinvertebrates can be used by people to assess water quality. Certain types of benthic macroinvertebrates cannot tolerate pollution, whereas others are extremely tolerant of it.  For example, if you were to turn over a few stones in a Northwest streambed and find caddisfly nymphs (pictured below encased in tiny pebbles), you would have an indication of good water quality. Caddisflies are very sensitive to poor water quality conditions.

Caddisfly nymphs encased in tiny pebbles on a river bottom.

Caddisfly nymphs encased in tiny pebbles on a river bottom are indicators of high water quality. (NOAA)

Surveys in Portland Harbor have shown that we have a pretty simple and uniform benthic macroinvertebrate population in the area. As you might expect, it is mostly made up of pollution-tolerant species. NOAA Restoration Center staff are leading restoration planning efforts at Portland Harbor and it is our hope that once cleanup and restoration projects are completed, we will see a more diverse assemblage of benthic macroinvertebrates in the Lower Willamette River.

Lauren SenkyrLauren Senkyr is a Habitat Restoration Specialist with NOAA’s Restoration Center.  Based out of Portland, Ore., she works on restoration planning and community outreach for the Portland Harbor Superfund site as well as other habitat restoration efforts throughout the state of Oregon.

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