Only eight percent of the approximately 170 million gallons of crude oil that flooded into the Gulf of Mexico was removed or burned. The rest was put into the environment; it dispersed or dissolved into the water column, floated to the surface, was deposited on the coast, or sank to the bottom. The extent of the damage to the Gulf is unknown and will take years to understand. Go below the surface of the Gulf oil disaster, hover on the blue bars to dive into the Gulf and hover over the (?) to learn more.

A large proportion of the oil evaporated into the air, including hazardous chemicals such as benzene and hydrogen sulfide. In the immediate aftermath, winds may have carried these toxic chemicals and hydrocarbons to shore, threatening the health of humans and wildlife.
A still unknown fraction of the spilled oil rose to the surface and produced thousands of oil slicks. These slicks traveled around the Gulf and inland, harming marine animals that utilize the sea surface, such as turtles, birds, marine mammals and larval fish, as well as coastal habitats such as the rich marshland.
After some of the lighter components of the oil evaporated, the crude mixed with water and became thick and gooey on the surface. Over time, the oil separated into smaller patches and, eventually, small tar balls. Tar balls can travel hundreds of miles and are very persistent in the marine environment. Tar balls from this disaster will continue to wash up on beaches for years to come.
Some of the oil was chemically and physically dispersed into the deep layers of the ocean water in miles-long plumes. The plumes of oil could contaminate any marine life that traveled through it, including hundreds of fish species, squid and marine mammals like the Gulf’s resident sperm whales.
Some of the oil has been degraded by marine bacteria naturally inhabiting the Gulf of Mexico; no one knows how much or what amount of the oil remains.
Copepods are small crustaceans found in the sea. They graze on plants and are in turn eaten by small forage fish. The copepods that weren’t wiped out by chemically dispersed oil may be contaminated by toxic hydrocarbons. They could transfer toxins up the food chain, harming dolphins, seabirds and large fish for decades.
Many fish spawn in the Gulf of Mexico in the spring, just when the oil rig exploded. Fragile eggs and larvae float in the upper layer of the water column, where a lot of the oil was. Fisheries experts suspect that many larval fish may not have survived the spill. The population-level impacts of this mortality will not be known for years.
The Gulf’s waters are home to hundreds of fish species that sustain life in the ocean and support the local seafood industry. Toxic elements of oil can persist in the food chain and contaminate seafood.
More than 30 distinct populations of bottlenose dolphins live in the Gulf. Dolphins give birth in the spring after nearly a year of gestation. Dolphin calves born into polluted waters may not have survived. Dolphins need to surface from the water to breathe, so they may have inhaled toxic fumes from the oil which could lead to respiratory problems, organ damage and possibly death.
All six species of sea turtles found in American waters — green, hawksbill, Kemp’s ridley, leatherback, loggerhead, and olive ridley — are either threatened or in danger of extinction. After the disaster, more than 400 sea turtles were rescued from oily waters, but more than 600 carcasses were found. Early estimates suggest that approximately half of these deaths were related to oil. Sea turtles often migrate long distances between foraging grounds and the beaches where they lay their eggs in the sand. The oil spill may have left turtles too ill to mate or lay eggs and contaminated their habitat.
More than 40 species of sharks are found in the Gulf. Oil may have harmed the seagrass beds that many sharks use as nurseries. The oil in the Gulf poses a critical threat to whale sharks because they are filter feeders who spend a considerable amount of time at the surface.
The entire western Atlantic population of bluefin tuna migrates into the Gulf to spawn from mid-April to June. Atlantic bluefin tuna is overfished and was a candidate for endangered species status even before the oil disaster. Experts still aren’t sure what will happen to the tuna of the Gulf.
A significant amount of oil settled onto the sea floor. Some of the oil smothered hard-bottom communities of sponges, seafans and corals that are important habitat for grouper and snapper — some of the Gulf’s most productive commercial fisheries.
Deep sea corals thrive without sunlight in the cold, dark depths of the Gulf. Scientists are still exploring the extent and diversity of deep sea reefs in the Gulf.
An estimated 170 million gallons of oil was released into the Gulf over 86 days. The magnitude of the damage will take years to estimate. Offshore drilling will always be risky, but the oil industry should have to demonstrate that it has adequate containment and clean-up capabilities.
Oil has been discovered on the bottom of the Gulf, where it appears to have smothered and contaminated the tracts of soft bottom, sponges, sea fans and coral reefs found in the rich bottom habitat of the Gulf.
There are less than 2,000 sperm whales in the Gulf of Mexico and the loss of only three populations could endanger the species’ long-term survival. Sperm whales, like dolphins, surface to breathe and can ingest oil. Oil may also have impacted the whales’ prey, like fish and squid. The harm to sperm whales remains unknown.

Illustrated and Designed by Jason Bishop ( for NRDC

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