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Oil Spill Affecting Marine Life, Top to Bottom

From nesting turtles to larval fish, Gulf ecosystem ravaged

The Humane Society of the United States

  • Pelicans at the Fort Jackson Oiled Wildlife Rehabilitation Center in Buras, Louisaian. Michelle Riley/The HSUS

by Sharon Young

Read all updates»

A large disoriented tiger shark swims near a Florida Beach. Dolphins are photographed swimming in an oil slick. Pelicans flounder in thick oil. We  see these ghastly images in the news every day.  

The impacts of the recent disaster caused by the explosion of the Deepwater Horizon oil rig continue to spread from the largest creatures to the smallest. 


As part of The HSUS team recently in the Gulf to assess wildlife impacts of the oil, I saw dying hermit crabs and other small creatures struggling in oily tide pools or unable to walk along the beach. 

Further up the food chain, I saw dolphins frolicking in the bays where some of them spend their entire lives. Although some live offshore, some spend their entire lives resident in a particular bay. Oil entering the only home they know can leave the dolphins no place to go.

The team also visited de-oiling facilities and saw the plight of the oiled birds first hand. It was a study in contrasting beauty and devastation.

Nesting and Mating Season at its Height

No time is good for a massive oil spill, but the timing could not have been worse for the Gulf of Mexico.  Endangered turtles are flocking to its beaches to nest, sharks and giant bluefin tuna are gathered there to spawn in the only known mating area for some of these species.  Countless bird species are in their nesting colonies and dabbling for food along the shoreline.

The oil affects virtually every kind of marine life in the rich ecosystems of the Gulf, from bottom to top of the food chain.  As oil spreads in the water column and oil-consuming microbes proliferate, oxygen is depleted. This oxygen poor environment can drive fish and other marine life into shallow waters in less affected areas. 

A Chain Reaction

The recent increase in numbers of deepwater sharks and large fish in coastal waters may be a result of chasing the schools of smaller fish that have moved there to avoid deeper oxygen-depleted waters. Oil also clogs the fragile gills of fish, crabs and other marine residents, preventing them from getting oxygen. The dispersants used to break up the oil are themselves deadly neuro-toxins.

Even air breathing animals such as turtles, dolphins and whales are affected because oil on the surface can contaminate their prey or be inhaled as they rise to breathe. The incidence of dolphins stranding on beaches is elevated all around the Gulf. Hundreds of endangered turtles have died, and now researchers are attempting to capture them at sea before they can swim into the oil. Some of these species such as Kemp’s Ridley turtles are already teetering on the brink of extinction.

On the surface, large floating rafts of a dense seaweed called Sargassum host micro-communities of larval fish, tiny marine creatures, crabs and juvenile sea turtles who feed on the abundant life in the Sargassum mats. These mats can also collect debris and oil and thereby doom the young generations of fish and turtles who start life sheltered in them. Deep below, sub-surface oiling of deep water coral beds that teem with life and are the base of a rich ecosystem is of considerable concern.

No End In Sight

The oil continues to spew from the broken well. Dispersants continue to be sprayed. Mats of Sargassum continue to be burned at sea. We may never know the full impact of this disaster.

Though we mourn for the dying birds and dead dolphins and turtles and even the tiny oil-drenched crab, they are simply a visible sign of a destruction that threatens the health of an entire ecosystem. Most of the destruction and loss of life will remain unseen and unaccounted but likely to affect the Gulf ecosystem and the animals and people who depend on it for years to come. 

Updates on the oil spill from the U.S. Fish and Wildlife Service can be found here»
The consolidated numbers of collected fish and wildlife affected by the oil can be found

Sharon Young is a member of the HSUS Oil Spill Assessment Team and is field director for marine issues for The HSUS.


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