A Titanic Issue: How PCBs Reached the Pacific Abyss
In the 1980s, an oceanic exploration team led by Dr. Robert Ballard attempted the impossible: to discover the wreck of the ill-fated Titanic. The Titanic – whose tale has been recapped in books, movies, and other avenues of popular culture since its tragic maiden voyage in 1912 – would be found at depths over 13,000 feet below sea level in the North Atlantic, meaning specialized deep-sea diving equipment had to be built to withstand pressures of roughly 15 pounds per square inch (PSI). After following two failed expeditions in 1981 and 1984 led by Jack Grimm, Ballard managed to gather investments from the US Navy to build an unmanned submersible robot which would be tethered to his ship by a sturdy cable “leash.” Rather than go off of the triangulated position of the Titanic’s last-known distress signal as his colleagues had done before him, Ballard realized a new method may work better. Rather than searching for the Titanic along the unmapped seabed as a “needle in a haystack,” Ballard surmised that ship wrecks – including the Titanic – would litter the seabed with debris as it sank. Wrecks in shallow waters would sink more or less vertically to the ocean floor, but as the Titanic sank nearly 2.5 miles down, the debris area from the colossal vessel had to be much larger.
Ballard’s hypothesis was correct, and on September 1st, 1985, an obstruction came into view of the submersible drone’s camera: a boiler. Ballard and his team followed the trail of bread crumbs as they appeared in shapes of warped rusted metal until the hull of the Titanic came into view.
One of the Titanic’s many boilers in the underwater debris field.
Dr. Ballard’s discovery rooted him in history as perhaps the most famous deep-sea explorer of our age. He continues to explore unmapped areas of the world’s oceans and is intrigued with what we can learn from the waters covering 70% of our planet, as only 5% of Earth’s oceans have been explored.
While Ballard’s expeditions continue to uncover the mysteries of the depths below our planet’s surface, he is not the first to conduct them, nor has he explored the deepest-known area of the ocean floor: the Mariana Trench.
The Mariana Trench mapped by the dark ridge on the eastern edge of the Mariana Islands in the Pacific Ocean.
Located on the border of the western Pacific Ocean and the eastern Philippine Sea, south of Japan and north of Papa New Guinea, the Mariana Trench is a 1,500 mile long, 40 mile wide crescent-shaped scar along the ocean floor. The Trench’s deepest point known as Challenger Deep lies some 7 miles below the surface. To put this in perspective, if you dropped Mt. Everest into Challenger Deep, the summit would still be more than a mile below the waves – so deep that sunlight could not reach it.
The Challenger Deep is named for the H.M.S. Challenger, a British vessel which first measured depths of the Trench to be 5 fathoms (roughly 4,475 feet) in 1875. That’s 28 years before the Wright brothers had their first successful flight in 1903 and 37 years before the Titanic set sail and sank in 1912. Another British vessel, aptly named Challenger II returned to the area in 1951 and measured the Challenger Deep to be closer to 7 miles below the surface using echo-sound mapping technology. Finally, in 1960, the Trieste submersible vessel reached the pitch-black depths of the Trench floor, measuring in at “6,300 fathoms” or 7.15 miles below the surface where the water temperature was measured to be 38 degrees Fahrenheit with pressures of 16,000 pounds or 8 tons PSI.
Despite the tremendous pressures, near-freezing temperatures, and distinct lack of any sunlight for over 6 miles through the water above, the two-man crew of the Trieste saw something incredible in this unforgiving environment: life. A single fish estimated to be some 18 inches in length appeared through the murk. Even in the darkest depths ever measured in Earth’s ocean, and despite the mere 20 minutes the Trieste spent along the Trench floor, the crew confirmed for themselves signs of life at 7 miles below the surface of the ocean. To quote Jeff Goldblum, “Life…finds a way.”
Photos of new species of deep-sea creatures found during Cameron’s 2012 dive.
Over 50 years later in 2012, famed movie director James Cameron would make a similar descent, but this time with lights and hi-definition cameras attached to the Deepsea Challenger submersible vessel. While most of the recorded footage did not obtain much media attention at the time due to “copyright protective coverings,” there were audio recordings from the depths that were available. Jennifer Frazer explains in her Scientific American article from April 2013 that through piecing bits of the two sources together she was able to detail some aspects of what was found at the bottom of the Trench.
“Amphipods…that fit in the team’s traps maxed out at 17 cm [long]. The ones that couldn’t reached 30. That’s one foot long.” Along with these large shrimp-like creatures were, “sea cucumbers…[which] specialize in roving the abyssal plains of the world, harvesting food from the sediment.” Eerily, these sea cucumbers, “were all pointed in the same direction,” and, “appeared to be frozen in place. The only thing that ever seemed to move were their feeding appendages.”
“A photo taken in 2009 by the unmanned submersible Nereus showing creatures at the bottom of the Mariana Trench.”
A brief video of some of the footage from the dive also showed a jellyfish as well as irregularly shaped structures resembling “crushed sand castles” home to Foraminifera, microscopic organisms which to an extent resemble large amoebas. What’s particularly interesting about these organisms, however, is that the “crushed sand castle” structure is actually a multitube network of these organisms allowing them to function similarly to as fungi would on land – working with bacteria in the abyssal zone to decompose organic compounds and return the minerals in these compounds to the sediment and gases to the water column. In short, it could be theorized that the presence of these organisms is what allows other species of life to grow and flourish at such depths by releasing oxygen gas back into the water.
Natalya Gallo, then a first-year graduate student of biological oceanography at Scripps Institute of Oceanography at UCSD, was a member of Cameron’s dive team. She estimated there may be 50-100 different species of Foraminifera in the Challenger Deep alone, and that’s not counting other species of micro-organisms.
Approaching this hypothesis from a scientific perspective means there must be one commonality across all forms of life in the Mariana Trench allowing them to thrive there. Food.
Organisms such as these commensal amphipods in the Mariana Trench feed off of scraps which are carried down from shallower oceanic regions.
The western Pacific Ocean is not primarily known for an abundance of food sources miles below the surface. Gallo claims that due to the distance from land and relatively inactive waters (compared to other oceanic areas) means that any bottom-dwelling life form making its home along the bottom of the Trench have mastered the ability to survive on scraps of any and everything they can get. The same holds true for the nearby New Britain Trench off the coast of Papa New Guinea. Although not as deep as the Mariana Trench (averaging roughly 4 miles deep compared to the Mariana’s 11 miles), this does allow for greater biodiversity in the New Britain trench, which in turn allows for more diverse sources of food. As Gallo is quoted in Frazer’s article, “the tale of these two trenches is a story of food.”
Likewise, New Britain Trench’s closer proximity to the landmass of Papa New Guinea makes it easier for debris from land to be eventually end up at the bottom of the Trench. “Palm fronds, leaves, sticks, and even coconuts” were seen by Gallo and other marine scientists from dive footage of the New Britain Trench. This debris is part of what attracts a broader range of marine life. Similarly, the scraps of this and other debris is carried away via oceanic current and underwater tectonic plate activity to other, deeper areas – including the Mariana Trench.
If we can understand how naturally-occurring debris such as plant material can originate on land and eventually end up miles below the ocean surface, we can then begin to understand how the same process can apply to other land-based materials. In particular, non-biodegradable materials that cannot be used as food by marine life. More definitively: man-made pollution.
Plastics and other man-made debris in the oceans have caused the Great Pacific Garbage Patch to become three times the size of France.
Any quick internet search including the words “ocean” and “trash” will result in an overwhelming number of articles and images detailing and showing the staggering amount of plastic and other waste we as humans have produced and allowed to wind up in our oceans. Perhaps the most famous example of this is the Great Pacific Garbage Patch – a coalesced mass of plastic garbage now twice as large as Texas. The Patch was first discovered in 1997 by Charles Moore, who was sailing home to California from Hawaii when he, “was confronted, as far as the eye could see, with the sight of plastic.”
And that’s just a piece of the problem.
In 2015, scientists estimated there to be some 5.25 trillion – with a “T” – pieces of plastic polluting the ocean, with nearly 270,000 tons of that floating on the surface. Below the waves, scientists believe there to be four billion pieces of microplastics per square kilometer on the floor of the deep sea.
Let’s recap real quick. Modern estimates of the Earth’s entire surface area, both underwater and on land, is said to be roughly 196.9 million square-miles, or 510 million square-kilometers. If we estimate Earth’s surface to be 70% covered by water, that means that there are 357 million square-kilometers of ocean floor, each one, potentially littered with four billion microplastics. Now, while I’m not sure off the top of my head what a number that large is called, I can show you what it looks like.
1,428,000,000,000,000,000,000 pieces of plastic across the ocean floors of the planet. Just plastic.
Not just debris – a crab has gotten tangled in plastic on the ocean floor.
We humans as a species have formed increasingly bad habits with disposing of our waste and its byproducts. If you read back through our previous blog blurbs and posts, it becomes quite clear that from the late 1800s through the 1970s and 1980s – before we were able to learn and know as much as we do know about the impact our actions have on our planet – it was largely assumed that waste runoff into rivers and lakes would eventually find its way to the ocean, where nature would “deal with it” in one way or another. This has yet to happen.
Debris from land can be carried out to sea and find its way to the sea bottom. Plastic has now shown to behave the same way. The difference between the two is that one is useful and biodegradable while the other, not being a naturally occurring substance doesn’t degrade when left to open exposure in the environment. Plastic is far from the only substance guilty of this behavior. Along with man-made plastics, a variety of man-made chemicals are unable to biodegrade naturally. Especially chemical compounds whose structure and physical nature cause them to be innately hydrophobic and therefore indissoluble in water.
In February of 2017, the results of a scientific study on the creatures which live in the Mariana Trench found that species of amphipods, smaller but similar to those Cameron’s team found during their 2012 dive to Challenger Deep, were contaminated with concentrations of PCBs, “50 times [higher] than crabs that survive in heavily polluted rivers in China.” The research team led by Alan Jamieson of Newcastle University in England found that the canyon slopes leading down into the Mariana Trench were littered with items of plastic garbage published their study in the Nature Ecology and Evolution journal. The study suggests, similarly to Gallo’s observations and research on the ecosystems in the Mariana Trench, that POPs including PCBs – much like land debris and plastic waste – manage to infiltrate the deepest depths of the ocean as they are carried there over periods of time by currents, tectonic activity, as well as through dead and decomposing organisms which sink to the seabed upon death.
A depiction of “Whale Fall” when whales die, fall to the abyssal zone of the ocean, and are consumed by smaller marine animals.
We here at ecoSPEARS have talked at length more months now how PCBs are hydrophobic and unable to dissolve naturally in water. Instead, they tend to find their way into sediments and are consumed by marine organisms. These organisms are eaten by larger organisms, which are eaten by fish which in turn are eaten by larger fish, which are then consumed by even larger apex marine predators such as sea lions and orcas. This process is called biomagnification or bioaccumulation.
PCBs are accumulated in fat when consumed, so larger predatory creatures with higher percentages of fatty tissue accumulate more dangerous concentrations of PCBs. When these creatures die and sink to the seabed, their bodies begin to decompose. This process of decomposition is expedited with the help of smaller lifeforms that make their home on and near the ocean floor including crustaceans, amphipods, and microscopic organisms. Since PCBs cannot dissolve or otherwise be naturally destroyed in the environment, these organisms all receive the accumulated concentration of PCBs the larger animal was contaminated with at the time of its death.
“The very bottom of the deep trenches like the Mariana are inhabited by incredibly efficient scavenging animals,” Jamieson said in response to his research findings, “so any little bit of organic material that falls down, these guys turn up in huge numbers and devour it.” Jamieson’s words mirror Gallo’s in response to her research on lifeforms in the Mariana Trench.
A year prior to Jamieson’s research being published, the US National Oceanic and Atmospheric Administration (NOAA) found that the slopes of the Sirena Deep – the canyon leading down into the Mariana Trench – were littered with other man-made garbage items including plastic bags and empty cans of food and beer.
A tin of Spam nearly 5,000 meters below the surface on the canyon slopes leading down to the Mariana Trench.
It seems that the ways in which both pollutants and non-pollutants eventually make their way to the depths of ocean are remarkably (if not, exactly) the same. Taking all of this research into account, we can begin to piece together the bigger picture of exactly how such tremendous amounts of human waste, pollution, and contamination works its way over decades from its origin point to more than 11 miles below sea level. As miraculous as it is to find such an abundance of thriving ecosystems in what might be the most unforgiving conditions on our planet, it is equally disturbing and disheartening to realize that our own pollution is so persistent that it remains as potent and dangerous today as it was forty, fifty or more years ago.
This is exactly the reason why our team here at ecoSPEARS relies on and builds upon education and awareness in everything we do. If there is little-to-no general awareness to a problem or the scale of it, how do you begin to engage with unaware populations? There’s no simple or easy answer to this question. But when we look back through history, we can see that whenever a population of people becomes aware of a problem, they are able to band together to fight for a solution.
Even Dr. Ballard during his famous expedition to find the Titanic knew that to find the wreckage, to learn from it and to expand upon that learning, he had to educate and engage with enough people to help reach that legendary milestone together. Prior to this, failed expeditions had rendered the endeavor “impossible.” But as Nelson Mandela famously said, “It always seems impossible until it is done.”
The PCB problem we have created and face as a species isn’t going away on its own. Even with billions of dollars being funneled into PCB remediation every year by hundreds of companies and agencies worldwide, there remains so much more work to be done. As an individual, recognizing the existence of a problem is the most important first step you can take, but it’s only the first step. No one has ever changed the world by themselves. It takes a team. It takes a community to help each other in order to achieve the change they want to see in the world. The larger the problem they face, the larger their community needs to be. And this problem is one we all face. It will require all of us together to recognize, address, and ultimately solve the problem.
But that first step always begins with you. Thanks for reading.
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