Oceans, caught between devil and the deep blue sea… (Pun intended!) – XI

Environmental effects of oil spill:

Hi friends, as I had mentioned in my last article “Oil Spill” comes as a bolt from the blue.  It often results in both immediate and long-term environmental damage. Some of the long-term ecological destruction can last for even decades after the spill occurs.

Once released into the aquatic system, oil coats everything it touches.  Thick grey, black sludge covers entire area even the shores.  It wraps beaches, rocks and each grain of beach sand.  It penetrates into animal and bird habitats on the coast and chokes their existence. If oil washes into coastal marshes, mangrove forests or other wetlands, fibrous plants and grasses absorb the oil, which can damage the plants and make the whole area unsuitable as wildlife habitat.  Various oil spills in Sunderbans in India is a stark example of this process. 

On 24th March 1989, Exxon Valdez, an Exxon Mobil’s vessel met with an accident in Alaskan seas.  She released over 41 million liters of oil into seas that covered over 2000 kilometers of shoreline.  Despite massive clean-up efforts following the spill, a 2007 study conducted by the National Oceanic and Atmospheric Administration (NOAA) found that almost 100,000 liters of oil were still trapped in the sand along the Alaska shoreline, even after 18 years.  Scientists involved in the study determined that this residual oil was declining at a rate of less than only 4 percent annually.

One of the significant environmental menaces from oil spills is that the oils penetrate into the structure of the plumage of birds reducing their ability to fly, and making them more vulnerable to temperature fluctuations (and leading to hypothermia or overheating).  Oils also make them much less buoyant in the water, eventually killing them.  Some birds exposed to petroleum experience changes in their hormonal balance, including changes in their luteinizing protein, which affect their reproduction capacity too. The majority of birds affected by oil spills die from severe biological complications.

Some studies have suggested that less than one percent of oil-soaked birds survive, even after cleaning.  During Torrey Canyon oil spill in 1967, world’s first major oil spill, over 25000 sea-birds on British shoreline were killed.  Whereas during Exxon Valdez spill in 1989, over 400,000 birds were killed.  


Oil spills also damage bird habitats and nesting grounds, which can have serious long-term effects on entire species. The 2010 BP Deepwater Horizon offshore oil spill in the Gulf of Mexico, for example, occurred during prime mating and nesting season for many bird and marine species, and the long-term environmental consequences of that spill won’t be known for many years.

As of mammals, such as whales, dolphins, seals and sea otters; oil spills kill them.  Oil coats the fur of sea otters and seals, reducing its insulating effect and leading to fluctuations in body temperature and hypothermia. Oil can also blind an animal, leaving it defenseless. The ingestion of oil causes dehydration and impairs the digestive process. Animals can be poisoned and may die from oil and other solvents like xylene, toluene, etc. entering their lungs or livers.  

The 2010 Deepwater Horizon oil spill in the Gulf of Mexico, one of worst environmental disasters in the United States, released about 4.9 million barrels (210 million US gal; 780,000 m3) of crude oil.  Both the spill and the clean-up efforts had effects on the environment.  The area of the spill has varied and rich marine ecology which includes more than 1,200 species of fish, 200 species of birds, 1,400 mollusks, 1,500 crustaceans, four types of sea turtles, and 29 species of marine mammals. 

In Gulf of Mexico spill, marine mammal researchers concluded that exposure to the oil caused a wide range of adverse health effects such as reproductive failures and organ damages in aquatic animals and that the animals killed contributed to the most significant and most extended marine mammal unusual mortality ever recorded in the Gulf of Mexico.  One of the worst-hit species during this spill was Dolphins.  In February 2011, the first birthing season for dolphins since the spill, it was reported that dead baby dolphins were washing up along the Mississippi and Alabama shorelines at about ten times the usual number.  From mid-January to late March 2011, scientists counted almost 200 dead dolphins in the Gulf, with another 90 in 2010.  On April 12, 2016, a research team reported that 88 percent of about 360 baby or stillborn dolphins within the spill area “had abnormal or under-developed lungs.”  


Oil spills often take a deadly toll on fish, shellfish, and other marine life, particularly if large numbers of fish eggs or larvae are exposed to the oil.  The shrimp and oyster fisheries along the Louisiana coast were among the first casualties of the 2010 BP Deepwater Horizon offshore oil spill. Similarly, the Exxon Valdez oil spill destroyed billions of salmon and herring eggs. Those fisheries still have not recovered.

The long-term damage to various species, and to the habitat and nesting or breeding grounds those species depend upon for their survival, is one of the most far-reaching environmental effects caused by oil spills. Even many species that spend most of their lives at sea—such as various species of sea turtles—must come ashore to nest. Sea turtles can be harmed by oil they encounter in the water or on the beach where they lay their eggs, the eggs can be damaged by the oil and fail to develop correctly, and newly hatched young turtles may be oiled as they scurry toward the ocean across an oily beach.

Ultimately, the severity of environmental damages caused by a particular oil spill depends on many factors including – the amount of the oil spilled, the type and weight of the oil, the location of the spill, the species of wildlife in the area, the timing or breeding cycles and seasonal migrations.  Even the weather at sea during and immediately after the oil spill also matters. But one thing never varies: oil spills are always bad news for the environment.


  1. Wikipedia
  2. National Oceanic and Atmospheric Administration
  3. The ThoughtCo

 Milind Joshi



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