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SOURCES OF oil in our waters
Ship leaving an oily trail.
Photo credit: US Department of Justice
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According to the National Academy of Sciences, people dump between 190 million and 706 million gallons of crude oil or its refined products into the sea each year. This represents more than half (fifty-two percent) of all the oil entering the ocean each year. The remainer comes from natural underwater seeps.
The single largest human cause of oil pollution in the oceans is oily waste illegally spilled from ships, which accounts for 46% of the oil entering the world’s oceans from human sources each year. |
Source: American Academy of Sciences, Oil in the Sea III, 2003
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Exxon Valdez Oil Spill. Credit: NOAA
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While industrial accidents like the Exxon Valdez, which spilled 11 million gallons of oil in 1989, or British Petroleum’s Deepwater Horizon, which released 210 million gallons of oil in 2010, attract the most media attention, industrial accidents like these represent just 18% of all the oil released into the water as a result of human activity.
Intentional illegal dumping of oil from ships represents 46% of the oil spilled into the world's waters, which is equal to eight new Exxon Valdez oil spills every year. |
Extent of illegal dumping
Source: US Department of Justice
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The world’s shipping fleet is comprised of nearly 88,000 vessels. About 50,000 of these ships trade internationally.
It is believed that 85-90% of the world fleet complies with the law. Unfortunately, that means between 5,000-7,500 vessels, routinely and intentionally discharge between 70 million to 210 million gallons of waste oil into the water each year. From aerial surveillance by governments around the world, we can see that illegal dumping by commercial ships is commonplace. It is also highly illegal. Learn about the laws against marine oil pollution. |
WHY DO MARINERS POLLUTE?Oil pollution is illegal, not to mention extremely harmful to the environment. So why do some ship owners and crew members still decide to pollute? It comes down to money.
Modern cargo and container ships are powered by oil-based fuels and lubricants, and leaks are commonplace. The heavy fuel oil that propels these ships produces an oily sludge when burned, and nearly all of the foul water, liquid waste and oil leaked from machinery drains down and accumulates in the bilge tanks. Oil tankers, in addition to accumulating regular operational waste, must also wash out their tanks between each trip, adding thousands of gallons of sludgy waste oil which must also be emptied regularly. A 2002 report by the European Organization for Economic Cooperation and Development estimated that the average annual cost of meeting the MARPOL regulations runs from $30,000 a year for an average sized cargo ship to $55,000 for a large container vessel, and the cost can rise to $150,000 per year for a very large oil taker. These costs represent, on average, between 3.5% and 6.5% of a ship's overall operating expenses. 
A "Magic Pipe." Source: US Department of Justice
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Source: US Department of Justice
Some ship operators and owners try to save money or the time it takes to unload waste oil in port by breaking the law by installing a pipe or hose, known in the shipping industry as a “magic pipe,” to bypass the ship's oily water separator and pump oily water directly into the ocean. This behavior was outlawed by the international marine pollution treaty known as MARPOL, which banned the dumping of oil into the water. Learn more about MARPOL and other Laws |
Impact on Fish
credit: Mark Caris, NOAA
When a large-scale spill happens, most fish avoid being smothered by simply swimming away. However, there is some evidence that fish can be drawn to oil floating on the surface of the water, perhaps in an attempt to hide in the shadows from predators. If oil coats the gills of these fish, they can die from asphyxiation.
Fish that are exposed to smaller amounts of oil often develop fin erosion, skin sores, liver damage, and cancer, and they can also bioaccumulate dangerous chemicals known as PAHs. In addition, they tend to produce fewer eggs, impacting future generations.
Bioaccumulation occurs when an organism survives exposure to a toxic agent but retains high concentrations of the toxin in their bodies. When humans or wildlife consume fish contaminated with high levels of PAHs, they are also exposed to the dangers of those toxins.
Fish that are exposed to smaller amounts of oil often develop fin erosion, skin sores, liver damage, and cancer, and they can also bioaccumulate dangerous chemicals known as PAHs. In addition, they tend to produce fewer eggs, impacting future generations.
Bioaccumulation occurs when an organism survives exposure to a toxic agent but retains high concentrations of the toxin in their bodies. When humans or wildlife consume fish contaminated with high levels of PAHs, they are also exposed to the dangers of those toxins.
Researchers at the National Oceanographic and Atmospheric Administration reported recently that direct contact with oil is not required for PAHs (the toxins in oil) to harm fish and other living organisms in the marine environment. They showed that exposure to even small concentrations of dissolved PAHs (as little as one part per billion of water) caused the death of pink salmon embryos. Other studies have shown that exposures to PAH concentrations as low as .7 parts per billion caused developmental malformations and genetic damage, decreased size at hatching, impaired swimming, and even death.
ResEArching oil impacts IN WOODS HOLE, MASSACHUSETTS
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Dr. John Stegeman, the director of the Woods Hole Center for Oceans and Human Health in Massachusetts, collects deep-sea fish from the middle of the Atlantic Ocean, a region once thought to be one of the purest on earth.
When oil is no longer visible in the water, many assume that it is no longer a problem. However, environmental toxicologists like Dr. Stegeman now know that this is not the case. Oil dissolved in water can be dangerous for fish, whales, sea turtles, and other wildlife, even in tiny amounts. How do researchers know if a marine animal has been exposed to oil? Some of the research on the effects of oil pollution in the water is carried out by studying a protein called Cytrochrome P4501A (CYP1A). When a fish comes into contact with oil, some of the most toxic parts of oil (known as polycyclic aromatic hydrocarbons, or PAHs) enter the bloodstream after being inhaled or absorbed through the skin. Once these PAHs are inside of the fish, they set off its cellular defenses. PAHs are recognized by receptors in the cell (known as aryl hydrocarbon receptors), which cause the cell’s defenses to leap into action and begin the production of CYP1A in an attempt to render the PAHs harmless. Unfortunately, sometimes PAHs are not neutralized by CYPIA and become even more toxic as a result of the cell’s attempts at self-defense. |
Dr. John Stegeman. Photo Credit: Common Good Productions
CYP1A, explains Dr. Stegeman, acts as a biological fingerprint that indicates if an organism has been exposed to the PAH's in oil. It's a unique bio-marker that “lights up” when a marine organism is exposed to the toxins in oil, causing "a cascade of cellular effects" which influence which genes are “turned on” in the DNA.
When a fish has been exposed to PAHs, the gene that produces CYP1A remains lit up, and its activation can be seen under a special microscope. This process creates a visible genetic trail that scientists can use to track exposure to oil pollution. And they are learning that the results of these genetic changes may be linked to reduced fertility, growth rates, and increasing susceptibility to cancer. Sadly, Dr. Stegeman’s research shows that even fish living deep in the middle of the ocean in what should be one of the cleanest areas on earth are now displaying signs of exposure to the toxins in oil. |
Studying Oil Toxicology at Woods Hole. Credit: Common Good Productions
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Photo Credit: Jed Goldstone, Woods Hole Oceanographic Institution
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IMPACT ON MARINE MAMMALS
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All marine mammals are susceptible to oil pollution when they ingest contaminated food. From whales to sea otters, all marine mammals exposed to oil can experience congested lungs, damaged airways, emphysema, stomach ulceration, hemorrhaging, eye lesions, skin lesions, and decreased weight and growth rates.
Because of their size, their range of habitats, and the difficulties of studying them within a lab, most of what scientists know about oil pollution and marine mammals comes from post-spill observation. What scientists do know for certain is that oil pollution is just as harmful to marine mammals as it is to all other forms of life. Whales
Baleen whales are highly susceptible to ingesting oil as a result of the way that they feed. These whales skim surface waters and take in huge amounts of water that they filter to collect their food. Oil residue can stick to the baleen, which lowers the amount of food that the whales can take in. This also exposes whales to the dangerous toxins present in oil. Dolphins Dolphins are most at risk when they inhale oil and oil vapor. When dolphins surface to breathe, oil can restrict their blowholes and airways. Dolphins surface for air more frequently when stressed, exposing them to even greater harm. Researchers have also found that dolphins can transfer toxic hydrocarbons from mother to child via milk. Seals and Otters Marine mammals with fur, such as otters or some seals, are also endangered by oil. Fur acts as an insulator and keeps otters and seals warm as they swim through icy ocean waters. When fur is matted by oil, these animals lose heat quickly and can die of hypothermia. Oil can also restrict movement, sometimes pinning flippers against bodies or making otters or seals too heavy to swim. Seals also use smell to identify their young, and oiled seal pups may be rejected and abandoned by their mothers if they smell too strongly of oil. |
 Photo Source: Exxon Valdez oil Spill Trustee Council
LESSONS FROM THE EXXON VALDEZ
On March 24, 1989, the tanker Exxon Valdez spilled nearly 11 million gallons of crude oil off the shore of Alaska. The oil would eventually impact over 1,100 miles of coastline, making it the second-largest oil spill to date in US history. The spill occurred at the beginning of the bird migration season. The U.S. Fish and Wildlife Service estimated that the spill killed 350,000 to 390,000 birds, especially common and thick-billed murres, assorted sea ducks, bald eagles, and pigeon guillemots; 3,500 to 5,500 sea otters; and 200 harbor seals. In addition, killer whales may also have been affected, as their numbers in the area declined shortly after the spill. Two years later, a study of the lasting impacts of the Exxon Valdez spill showed that mortality rates in pink salmon eggs were 96% higher than pre-spill levels. There was a mystery there. While the visible presence of the oil had disappeared, its impact continued to be felt. Today, more than two decades later, we think we know the answer. Recent studies are finding that even indirect exposure to small amounts of the toxins in oil can have profound impacts on animal life, particularly on the young. |
source: NOAA
SEABIRDS
Seabirds spend most of their lives on the water, making them particularly vulnerable to the effects of oil pollution. A Canadian government study in 2002 estimated that approximately 300,000 seabirds are killed each year off the Grand Banks as a result of illegal discharges of oil from ships. This study also collected oil from bird plumage in the Atlantic and the North Sea over a 10-year period and found that more than 90 percent was composed of heavy fuel oil mixed with lubricating oil, which is only found in the bilges of large ships.
Seabirds spend most of their lives on the water, making them particularly vulnerable to the effects of oil pollution. A Canadian government study in 2002 estimated that approximately 300,000 seabirds are killed each year off the Grand Banks as a result of illegal discharges of oil from ships. This study also collected oil from bird plumage in the Atlantic and the North Sea over a 10-year period and found that more than 90 percent was composed of heavy fuel oil mixed with lubricating oil, which is only found in the bilges of large ships.
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Oiled Feathers
Oil is particularly threatening to seabirds because it forms a thin layer on the surface of the water where many seabirds spend most of their time. This means that almost any amount of oil discharged into the water is a threat to seabirds. Seabirds can be affected by external exposure to even small amounts of oil because their feathers absorb oil very readily and decreases the feather’s ability to insulate a seabird from cold waters; it also decreases their waterproofing and buoyancy. It can also destroy the delicate hooks and barbs that normally interlock and keep the water away from a seabird’s skin, exposing it to cold waters and leading to death from hypothermia. Oiled feathers can also severely impact a seabird’s ability to fly and find food, causing it to starve to death. Seabirds may also ingest oil directly while preening their feathers, which can lead to fatal or debilitating effects on seabirds’ internal organs and can cause lesions in their kidneys, livers, and stomachs. Seabirds that consume oil have been found to grow more slowly and show impaired development of flight feathers. An oil spill does not have to be large in order to devastate a bird population. In 1978, the Amoco Cadiz spilled over 220,000 tons of oil off the coast of France, resulting in the death of only 5,000 birds. Two years later, 600 tons of oil spilled in a strait separating Norway from Denmark ultimately killed some 30,000 birds. Oil, Eggs and Chicks Bird eggs are also extremely susceptible to oil pollution and can be damaged by contact with small amounts of oil. |
Photo credit: AP
Eggs are vulnerable if they are incubating near a shore that is oiled or if their parents have oil on their feathers when they return to the nest. Oiled eggs see decreased hatch rates. Eggs that do hatch often produce offspring with bone and bill deformities as well as with reduced liver sizes and growth rates.
Researchers studying a breeding group of South Polar skuas following an oil spill in Antarctica near Palmer Station in 1989 witnessed a 100% mortality rate among chicks. They found that adult skuas that became oiled while hunting for food would travel to freshwater ponds to clean themselves instead of returning immediately to their nesting areas. This delay caused a breakdown in pair coordination, which left chicks unguarded. Within a few weeks after the spill, every chick in the colony was dead, killed by other skuas, despite never coming into direct contact with oil. |
TYPES OF OIL
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HEAVY OILS
Heavy oils, such as bunker fuels, crude oil, and No. 6 fuel oil, are the most common type of ship fuel. When spilled, these oils create thick, dark slicks that do not evaporate when exposed to sunlight. They eventually spread out to form smaller, discrete patches or streaks. Environmental Impacts: Heavy oils impact every area of the marine environment. They can coat birds and fish, restricting their movement, covering their airways, and smothering them to death. When responders act quickly, heavy oils can be contained and collected by skimmers or vacuum pumps. They can float at the surface, remain suspended in the water column, or sink to the seafloor, where they can remain for many years. Direct contact with heavy oil is toxic to fish. It can also bioaccumulate in crabs and other shellfish, making then unsafe for human consumption. Birds and mammals are also affected by direct contact or ingesting the oil. |
Tar ball washed up on a beach.
Source: NOAA
Heavy oil can form tar balls when mixed with air and agitated by the movement of waves in a process known as weathering. Tar balls can travel great distances and eventually wash up on shore.
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LIGHT OILS
Marine diesel and No. 2 fuel oil, used for smaller commercial vessels and recreational boats, are categorized as “light oils.” They usually create a dull, dark colored film when spilled into the water, which spreads quickly creating a rainbow or silvery sheen on the water. A sheen is a thin layer of oil (less than 0.0002 inches or 0.005 mm) floating on the water’s surface. One gallon of light oil can cover more than a full square mile, forming the tiniest film on the surface at one-hundredth of a millimeter thick. Environmental Impacts: Light oils evaporate or dissipate quickly from the surface of the water and are easily mixed into the water column. They do not usually settle on the seafloor, but can be absorbed into sediments or dispersed into small droplets that stay suspended in the water. While light oil spills might seem to disappear quickly, it can take months for the last traces to leave the environment. Even very thin sheens can do great harm to these animals. 
Silvery sheen spill. Source: NOAA
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MEDIUM OILS
Most crude, or naturally occurring oils, fall into the category of medium oils. The Deepwater Horizon spill of 2010 released an estimated two hundred and ten million gallons of medium crude oil into the Gulf of Mexico.  BP Deepwater Horizon on fire. Source: NOAA
Environmental Impacts: While roughly one-third of spilled crude oil will evaporate within 24 hours, medium oil spills can cause serious long-term contamination. Medium oil is heavy enough to settle down onto the seafloor, which means that it can take years for it to finally leave the environment. |