National Oceanic and Atmospheric Administration 

U.S. Department of Commerce 

NOAA’s Oil Spill Response 

Effects of Oil on Marine Mammals

and Sea Turtles
 

 


Oil is a mixture of chemicals, all of which may have different effects on marine animals and the 

combination may be even more hazardous. In addition, 

some of the chemicals and methods used to clean up oil 

spills may also have effects on marine animals. Toxicity 

or harmful effects are dependent upon: 

4 The mixture and types of chemicals that make up the 

oil or are used to clean up the oil. 

4 The amount of exposure (dose for internal exposures 

or time for external exposures). 

4 The route of exposure (inhaled, ingested, absorbed, 

or external). 

4 The biomedical risk factors of the animal (age, sex, 

reproductive stage, and health status). For turtles this 

will include differing impacts and vulnerabilities at the 

different life stages such as eggs, post-hatchlings, 

juveniles and adults. For cetaceans this will include 

neonates, calves, juveniles and adults. 

Research on dolphins in human care has shown that 

the animals avoid oil on the surface of the water, however 

observations of wild dolphins have documented the 

animals swimming in, feeding in and socializing in oiled 

water during previous oil spills in the Gulf of Mexico. 

Several aspects of sea turtles put them at risk, 

including the lack of avoidance behavior of oiled waters 

and indiscriminate feeding in convergence zones. 

Whales, dolphins, 

manatees and sea 

turtles are air breathers 

and all must come to 

the surface frequently 

to take a breath of air. In a large oil spill, these animals 

may be exposed to volatile chemicals during inhalation. 

Depending on the size of a particular spill, marine 

mammals and sea turtles could be exposed to these 

chemicals for a fairly long time. 

General Types of Effects on Marine Mammals 

and Sea Turtles 

The following are generalities and would need to be 

specifically applied to the situation or event. 

Cetaceans, manatees and 

sea turtles may be exposed to 

chemicals in oil (or used to 

treat oil spills like dispersants) 

in two ways: internally (eating 

or swallowing oil, consuming 

prey containing oil based 

chemicals, or inhaling of 

volatile oil related compounds) and externally 

(swimming in oil or dispersants, or oil or dispersants on 

skin and body). 

(continued on back) 
Additionally sea turtles may experience oiling 

impacts on nesting beaches and eggs through chemical 

exposures resulting in decreased 

survival to hatching and developmental defects in hatchlings. 

External Effects 

4 Cetaceans and manatees have no 

fur which can be oiled and do not 

depend on fur for insulation. 


Therefore they are not susceptible 


to the insulation effects 


(hypothermia) that often puts haired marine 


mammals (such as fur seals or sea otters) at risk.
 

4 Oil and other chemicals on skin and body may result in 

skin and eye irritation, burns to mucous membranes of 

eyes and mouth, and increased susceptibility to 

infection. For large whales, oil can foul the baleen they 

use to filter-feed, thereby potentially decreasing their 

ability to eat. 

Internal Effects 

4 Inhalation of volatile organics from oil or dispersants 

may result in respiratory irritation, inflammation, 

emphysema, or pneumonia. 

4 Ingesting oil or dispersants may result in 

gastrointestinal inflammation, ulcers, bleeding, 

diarrhea, and maldigestion. 

4 Absorption of inhaled and ingested chemicals may 

damage organs such as the liver or kidney, result in 

anemia and immune suppression, or lead to 

reproductive failure or death. 

Summary 

4 Direct contact with of petroleum compounds or 

dispersants with skin may cause skin irritation, 

chemical burns, and infections. 

4 Inhalation of volatile petroleum compounds or 

dispersants may irritate or injure the respiratory tract, 

which may lead to 

inflammation or pneumonia. 

4 Ingestion of petroleum 

compounds may cause injury to 

the gastrointestinal tract, which 

may affect the animals’ 

ability to absorb or digest foods.

4 Absorption of petroleum 


compounds or dispersants 

may damage liver, kidney, and 

brain function as well as causing anemia and 

immune suppression. 

4 Long term chronic effects such as decreased survival 

and lowered reproductive success may occur. 

4 The Marine Mammal and Sea Turtle Stranding 

Networks have protocols and procedures in place for 

responding to live animals that are exposed to oil spills, 

and animals brought into rehabilitation facilities are 

provided veterinary care to remove oil and treat any 

related health effects. 

Learn more about NOAA’s response to the BP oil spill 

at http://response.restoration.noaa.gov/deepwaterhorizon. 

To learn more about NOAA, visit http://www.noaa.gov. 

May 12, 2010