Every kind of marine animal in the Gulf of Mexico, from dolphins, turtles and seabirds to single-celled plankton, could be affected by the oil contamination in the Gulf. Images of oiled sea turtles, pelicans and dolphins continue to provoke public outcry. These charismatic animals are among the most visible, yet they are really just the signature species that represent an entire ecosystem under threat. This page highlights likely effects of the oil spill on cetaceans (dolphins and whales), sea turtles, birds, fishes, coastal wetlands and intertidal zones, and the overall ecosystem.

Cetaceans (dolphins and whales)

Dolphins in the bow wave of a

NOAA vessel in the Gulf of Mexico

(Photo: NOAA)

When whales, dolphins and porpoises surface to breathe, oily water can cover their blowholes and enter their lungs, making breathing difficult. Oil can get into the animals’ eyes, potentially causing damage to vision. It can also enter their mouths, where it can be ingested, potentially damaging internal organs. Oil contamination is likely to have detrimental effects on cetacean reproduction and long-term health.

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Sea turtles

A nesting Kemp's ridley sea turtle at South

Padre Island. (Photo: Jessica Lavash)

Five of the world’s seven sea turtle species can be found in the Gulf. The region is the only major habitat for adult Kemp’s ridley sea turtles, which are the most endangered species of sea turtles. When sea turtles surface in oil-covered water, they can breathe in the oil vapors and residues, which can get into their lungs and cause major respiratory problems. Oil can get into the animals’ eyes, potentially causing damage to vision. If oil gets into sea turtles' mouths and they ingest it, it can potentially damage their internal organs.

This oil spill happened at the beginning of the breeding season, when adult Kemp’s ridleys had started to migrate across the Gulf to critical breeding beaches near the Texas/Mexico border. Hatchling and juvenile turtles are small enough that thick oil may prevent them from surfacing to breathe. These young turtles drift in currents and will congregate in the same areas where spilled oil converges, amplifying the risks they face.

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Brown pelican

(Photo: Alan D. Wilson, Wikimedia Commons)

Seabirds get covered with oil while diving into oily waters to fish. The birds may ingest oil when they eat prey that is covered in or has ingested oil. Once birds are covered with oil, they have difficulty flying, or are completely unable to fly, making feeding and getting away from predators impossible. Many species of birds, including the brown pelican (just taken off the endangered list) face threats from the oil spill on the coastal islands and wetlands of the Gulf that they use as rookeries. Birds’ eggs are getting covered in oil, and the birds are deserting their oiled habitat, leaving their eggs behind.

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Bluefin tuna (Photo: Brian Skerry)

Scientists have observed fish species moving into near-shore areas with less oil contamination, indicating that they may be fleeing significant habitat impacts in deeper waters. The Gulf is a breeding ground for bluefin tuna, and the oil spill coincides with egg production. Larvae of tuna and other fishes eat anything they see in the water, including oil droplets. Studies on a variety of fish larvae suggests that ingestion of both oil droplets and dispersants causes adverse effects, including mutations, physiological problems and increased mortality.

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Coastal wetlands and intertidal zones

Rainey Refuge marsh in Louisiana.

(Photo: NOAA)

The Gulf of Mexico contains nearly half of the coastal wetlands in the United States. Marshes, estuaries and bayous provide critical nursery and feeding grounds for hundreds of marine species. A large percentage of marine species that live in the open ocean as adults spend one critical life stage in coastal wetlands. Earlier oil spill studies in a comparable ecosystem showed extensive mortality in mangroves, sea grasses, coral reefs and algae from the spill.

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Ecosystem effects

Oyster hatchery in Grand Isle, Louisiana

(Photo: Louisiana Sea Grant College Programs)

Clean up efforts have included unprecedented amounts of chemical dispersants, which are used to break up oil slicks. Although detailed effects of the chemical dispersants on wildlife and ecosystems are not well studied, the chemicals used are toxic to a variety of organisms, and they have never been previously used on this wide a scale. Because dispersants break oil up into tiny droplets, marine biologists fear that fish larvae, zooplankton and filter feeders (such as oysters), will be at risk from eating the large quantities of “non-visible” oil.

Chemical dispersants are likely to impact deep-water animals downstream of the well. Oil will likely reduce the amount and health of all prey species, reducing the food available for marine mammals, seabirds and sea turtles. Plankton is the foundation for nearly all life in the Gulf of Mexico (and the ocean), and they will most likely be affected. Contaminants from the spill and the dispersants are likely to concentrate in the upper food chain, affecting whales, dolphins, birds and sharks.

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