Impact of Oil Spills on Marine and Terrestrial Ecosystems

Oil Spill Damage

The effects of oil spills have had lasting effects on the marine and terrestrial ecosystems that affect the respiratory, food chain, and reproductive systems of marine and terrestrial wildlife for decades. "Human activity has depleted marine species 90%, seagrass and wetland habitat 65%, and degraded water quality 10-1,000 fold" (Narisimha). A major portion of these statistics has been due to oil spills. It has been difficult for scientists to measure the actual effects of an oil spill due to the fact that one oil spill has affects that last decades. There has been more than 320 known offshore drilling oil spills since 1964 alone (A Deadly Toll: The Gulf Oil Spill and the Unfolding Wildlife Disaster, 2011).

On April 20, 2010, BP spilled 205.8 million gallons of oil and 225,000 tons of methane in the Gulf of Mexico over a three-month time period, creating one of the largest oil spills in U.S. history (A Deadly Toll: The Gulf Oil Spill and the Unfolding Wildlife Disaster, 2011). Recovery efforts only cleaned up approximately 25%, leaving approximately 75% that dispersants was used to break up the oil hydrocarbon particles. Nearly two million gallons of the toxic dispersants were sprayed into the ocean to break up the particles.

The total effects of the BP oil spill are still not known and may never really be known. At the time of the three-month incident, it was said to have caused at least 102 species of birds, 6,000 sea turtles, 25,900 marine mammals, and an unknown number of fish to die. A year later, there were still dead turtles, marine mammals, birds, and fish that were still washing up on beaches. This was only the ones that washed up on the beaches and was counted. It did not include the animals that did not wash up on shores and could have just floated to the bottom of the ocean. There is really no way to determine exactly how many animals died from the oil spill and how many died from other causes, more especially where they were oil coated.

The oil alone has negative impacts on mammals (Oil Spill Impacts on Mammals). Direct impact with the oil causes chemical burns and irritation. Ingestion of oil particles causes ulcers and internal bleeding. The surface oil emits fumes that get breathed by mammals when they swim to the surface that causes respiratory problems. The baleen, a part of the mouth of toothless whales that filters prey from ingested water, becomes ineffective from being coated by oil particles. Prey animals absorb oil particles that get passed on to mammals as they eat the prey animals. Terrestrial mammals, river otters, mink, and swamp rabbits, lose habitat and food sources as oil washes into coastal wetlands. The oil particles also cause complications in the reproductive systems making recovery of the species slow.

The use of dispersants causes a decrease in risk to water surface and shore habitat, but increases risk in water column organisms and organisms on the sea floor (Schor, 2010). This only shifts the problem from one part of the ecosystem to another. The shifting of the affects with dispersants is from the larger fish to the organisms they feed on creating a problem with the food chain for the wildlife (asladirt, 2010).

There have been gaps in the testing of dispersants. Most of the test only test the acute effects where little testing has been done on the chronic toxicity. The studies have also not examined the long-term effects of the dispersants. By using the dispersants to break up the oil hydrocarbon particles, it has added to damage from the oil and methane. Other than the shifting of the problem in the ecosystem, it still is not known to what extent the dispersants add to the damage of the oil spill.

There is also the problem of undersea oil patches creating oxygen depleting "dead zones" in the ocean. As the areas of "dead zones" expand, it causes an oxygen problem in the ocean. This puts the water column animals at greater risk. Where water surface animals can go to the surface for oxygen, the water column animals do not have the ability to breathe in the dead zones. At the same time, the larger animals are put at risk because they feed from the water column animals. As the water column animals are put at risk of oxygen dead zones, the larger animals lose their food chain.