When the Deepwater Horizon oil rig exploded in 2010 it spewed over 210 million gallons of oil into the Gulf of Mexico. Shortly thereafter it is estimated that over two million gallons of toxic chemical dispersants were poured into the ecosystem. This was the largest accidental oil spill in the history of the petroleum industry and the chemical dispersants used had never been used before in such large quantities. Although the immediate effects of the oil and the dispersant were obvious – massive amounts of oil soiling the Gulf beaches, thousands of birds covered in oil, and countless fish and marine mammal deaths – the chronic effects are unknown and still somewhat unstudied.
The Gulf is home to more than 8,300 species of fish, birds, molluscs, crustaceans, sea turtles, and marine mammals which are listed below. However, on Operation Toxic Gulf the Sea Shepherd/Ocean Alliance team will be studying sperm whales because they are an apex predator at the top of the food chain and therefore act as a good bio-indicator of the health of the entire ecosystem.
The sperm whale is one of the deepest diving whales, descending as far as two miles below sea level. This species is the largest toothed predator ever known to have lived on Earth. There is a resident population of about 1,600 sperm whales in the Gulf of Mexico. This population is endangered, as all sperm whales are, but this population is considered to be at particular risk because the size of the group is so small. Losing even a few whales will have dramatic population effects because individual whales take a long time to reach sexual maturity and then only produce a few calves over their lifetimes. The Gulf Oil Spill is a specific threat to these sperm whales, because they occupy deeper waters and thus are much closer to the greatest amount of oil. Moreover, studies show that prior to the explosion, many sperm whales spent a lot of time near the Deepwater Horizon oil rig.
Oil can have immediate and long-term impacts on whales and other marine mammals. Marine mammals breathe air and, thus, if they surface to breathe in an oil slick, they can inhale the oil, resulting in respiratory issues. Even if they do not surface within the slick itself, they may inhale sufficient amounts of the strong fumes emanating from the slick that can render them unconscious and cause them to drown. Oil can contaminate their food, and if they eat it, they can experience digestive disorders and immune system effects. Oil can also have long-term effects such as damaging their DNA. If this occurs, it can impair the whales’ ability to reproduce, thus, reduce the number of calves born. The impacts of oil on whale populations were seen after the Exxon Valdez oil spill. That oil decimated the Orca Whale population, reducing it by 40%. Experts predict that this population will ultimately go extinct.
More animals found in the Gulf of Mexico
There are five species of sea turtle in the Gulf Coast and all are threatened. Sea turtles are not only vulnerable to eating contaminated fish, but were also at risk of ingesting and inhaling the oil when coming up to the surface for air.
Sea birds feel the immediate effect of oil spills strongly. When oil sticks to birds' feathers, it allows water to penetrate through to their bodies, with the result that they can die from hypothermia or drowning. The oil also makes it impossible for them to fly and find food. It can also cause internal poisoning when it is ingested from cleaning their feathers or eating contaminated fish.
Brown pelicans – This state bird of Louisiana nests on barrier islands and feeds near shore. Removed from the U.S. Endangered Species Act list only a few years ago, brown pelicans remain vulnerable, and their relatively low reproductive rate means that any disruption to their breeding cycle could have serious effects on the population. Because brown pelicans dive into the water for food, they are threatened by eating contaminated fish (and feeding them to their young).
Heron - Many species of heron breed in the region affected by the oil spill, including Louisiana herons, black-crowned and yellow-crowned night herons, green herons, and little blue herons. They nest in large colonies called rookeries and many of them feed in the marshes along the coast that were coated with oil.
Egrets - As with herons, there are many species of egrets that feed and nest in the coastal areas now being contaminated by the mass amounts of toxic oil. These species include snowy, reddish, and great egrets.
Terns- Terns nest along Gulf Coast beaches as part of their migratory journey and feed on fish and other marine life making them extremely vulnerable to the immediate effects of oil on the surface or washing ashore.
Other birds particularly at risk include the piping plovers, American oystercatchers, and reddish egrets (Breton Sound Island). The long-term effects of the oil spill and the dispersants used on the bird populations are unknown.
Dolphins -3,000 to 5,000 dolphins live around the Mississippi waters, and 75,000 call the Gulf of Mexico home. Because dolphins have to rise to the surface frequently to breathe, the oil spill was especially dangerous for them in the short term and many deaths occurred. In the long term, oil and dispersants contaminating their food supply puts them at risk.
Bryde Whales – Bryde’s Whales are filter feeders having baleen plates instead of teeth. Their feeding methods include skimming the surface for plankton, krill, and schooling fish. There is only a small population of Bryde’s Whales in the Gulf and it is unknown what the chronic effects to their population will be.
Manatees – Manatees migrate from Florida to Louisiana waters every summer. There is little research being conducted on how manatees may be affected by the oil disaster.
Fish and Shellfish
Atlantic Bluefin Tuna - Already facing extinction from overfishing, the Atlantic Bluefin Tuna were struck with another disastrous blow when oil began spilling into the Gulf, an area they migrate to in March, staying until June. May and April are peak spawning months for them and the Gulf is the only documented spawning ground for the Western Bluefin. Unfortunately, the chemical dispersants being used on the spill may make things worse for the Bluefin, as they sink the oil below the surface and into the area where delicate Bluefin eggs and larvae are floating.
Oil spills can affect all the animals in the oceans – plankton, larval fish, and bottom-dwelling organisms, seaweed, clams, oysters, and muscles. The species that feed on these smaller organisms, such as sperm whales, then accumulate the toxins within themselves and they build up over time.