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8/8/2019 Oil Spill Fact Sheet
http://slidepdf.com/reader/full/oil-spill-fact-sheet 1/2
The U.S. Fish and Wildlife Serviceis the federal agency responsible for many of the nation’s sh and wildliferesources. Having this responsibilityhas established the agency as one of theprimary trustees for sh, wildlife andhabitat at oil spills.
Oil spills affect wildlife and their
habitats in many ways. The severityof the injury depends on the type and
quantity of oil spilled, the season andweather, the type of shoreline, and the
type of waves and tidal energy in thearea of the spill.
Oil can be categorized into ve groups,
ranging from very light to very heavyoils. Most oil has a density less thanwater, so it oats. Oil tends to spread
into a thin layer on the water surface asa sheen. Once in the water, oil undergoes
weathering, a process that describesthe physical, chemical, and biological
changes that occur when oil interactswith the environment.
Weathering reduces the more toxic
elements in oil products over time, asexposure to air, sunlight, wave andtidal action, and certain mircoscopic
organisms degrades and/or dispersesoil. Weathering rates depend on
factors such as type of oil, weather,temperature, and the type of shoreline
and bottom that occur in the spill area.
Types of Oil Very light oils (jet fuel, gasoline) are
highly volatile and evaporate quickly.Very light oils are one of the most
acutely toxic oils and generally affect
aquatic life (sh, invertebrates, and
plants) that live in the upper water
column.
Light oils (diesel, light crude, heating
oils) are moderately volatile and canleave a residue of up to one third of the
amount spilled after several days. Lightoils leave a lm on intertidal resources
and have the potential to cause long-term contamination.
Medium oils (most crude oils) are less
likely to mix with water and can causesevere and long-term contamination to
intertidal areas. Medium oils can also
severely impact waterfowl and fur-bearing marine mammals.
Heavy oils (heavy crude, No. 6 fuel oiland Bunker C) do not readily mix with
water and have far less evaporationand dilution potential. These oils tendto weather slowly. Heavy oil can cause
severe long-term contamination of intertidal areas and sediments. Heavy
oils have severe impacts on waterfowland fur-bearing marine mammals.
Cleanup of heavy oil is difcult and
usually long-term.
Very heavy oils can oat, mix, sink, or
hang in the water. These oils can beco
oil drops and mix in the water, oraccumulate on the bottom, or mix withsediment and then sink.
Wildlife and HabitatOil causes harm to wildlife throughphysical contact, ingestion, inhalationand absorption. Floating oil can
contaminate plankton, which includesalgae, sh eggs, and the larvae of
various invertebrates. Fish that feedon these organisms can subsequently
become contaminated. Larger animals
in the food chain, including biggersh, birds, terrestrial mammals, and
even humans may then consumecontaminated organisms.
Initially, oil has the greatest impacts o
species that utilize the water surface,such as waterfowl and sea otters, and
species that inhabit the nearshoreenvironment. Although oil causes
immediate effects throughout the entispill site, it is the external effects of oon larger wildlife species that are ofte
immediately apparent.
Plants
Marine algae and seaweed responds
variably to oil, and oil spills may resulin die-offs for some species. Algae
may die or become more abundant inresponse to oil spills. Although oil can
prevent the germination and growthof marine plants, most vegetation,including kelp, appears to recover afte
cleanup.
Effects of Oil Spills on Wildlife and Habitat
Alaska Region
Pool of oil on a heavily impactedbeach, Prince William Sound, AK.NOAA
Sediment plume and sheens of reoated oil, Prince William
Sound, AK. NOAA
8/8/2019 Oil Spill Fact Sheet
http://slidepdf.com/reader/full/oil-spill-fact-sheet 2/2
sensitive to oil toxins.
Birds and Mammals
Physical contact with oil destroys theinsulation value of fur and feathers,
causing birds and fur-bearing mammalsto die of hypothermia. In cold climates,
an inch diameter oil drop can be enoughto kill a bird. Heavily oiled birds can
loose their ability to y and theirbuoyancy, causing drowning.
In efforts to clean themselves, birds
and sea otters ingest and inhale oil.Ingestion can kill animals immediately,but more often results in lung, liver, and
kidney damage and subsequent death.Seals and sea lions may be exposed to
oil while breathing or resting at thewater’s surface or through feeding on
contaminated species.
Long-term or chronic effects onbirds and marine mammals are less
understood, but oil ingestion has beenshown to cause suppression to theimmune system, organ damage, skin
irritation and ulceration, damage to theadrenal system, and behavioral changes.
Damage to the immune system canlead to secondary infections that cause
death and behavioral changes may affectan individual’s ability to nd food or
avoid predators. Oil also affects animalsin non-lethal ways such as impairingreproduction.
Avian and mammalian scavengerssuch as ravens, bald eagles, and arcticfoxes are also exposed to oil by feeding
on carcasses of contaminated sh andwildlife. Direct mortality and reduced
reproduction in bald eagles were
attributed to the Exxon Valdez oil spi
Habitat
Oil has the potential to persist in theenvironment long after a spill event a
has been detected in sediment 30 yearafter a spill. Oil spills may cause shift
population structure, species abundanand diversity, and distribution. Habit
loss and the loss of prey items also hathe potential to affect sh and wildlifepopulations.
Oil remains in the environment long
after a spill event, especially in areassheltered from weathering processes,
such as the subsurface sedimentsunder gravel shorelines, and in somesoft substrates. However, pelagic and
offshore communities are fairly resilieand rebound more quickly than inshor
habitats. Although oil is still present
in the sediment and coastal areas 15years after the Exxon Valdez oil spillin Prince William Sound, Alaska, somwildlife populations have recovered. I
is believed that continued effects willmost likely be restricted to population
that reside or feed in isolated areas thcontain oil.
The U.S. Fish and Wildlife Service
responds to spills to minimize impactsto trust resources and continues its
work long after a spill event. The
Service continues assess and monitorthe damage to habitat and wildlife and
attempts to minimize the long-termeffects on new generations of wildlife
U.S. Fish & Wildlife Service1 800/344 WILDhttp://www.fws.gov
For more information, contact:U.S. Fish and Wildlife Service
Regional Spill Response Coordinator1011 E. Tudor Road Anchorage, Alaska 99503
907/786 3598
Visit the Contaminant Program home paghttp://alaska.fws.gov/sheries/
contaminants/index.htm
December 2004
Oily sheen in the intertidal habitat with aquatic plants following theExxon Valdez spill.
Oiled loon, Prince William Sound, AK.
Invertebrates
Oil can be directly toxic to marineinvertebrates or impact them throughphysical smothering, altering metabolic
and feeding rates, and altering shellformation. These toxic effects can be
both acute (lethal) and chronic (sub-lethal). Intertidal benthic (bottom
dwelling) invertebrates may beespecially vulnerable when oil becomeshighly concentrated along the shoreline.
Additionally, sediments can becomereservoirs for the spilled petroleum.
Some benthic invertebrates can surviveexposure, but may accumulate high
levels of contaminants in their bodiesthat can be passed on to predators.
Fish
Fish can be impacted directly throughuptake by the gills, ingestion of oil oroiled prey, effects on eggs and larval
survival, or changes in the ecosystemthat support the sh. Adult sh may
experience reduced growth, enlargedlivers, changes in heart and respiration
rates, n erosion, and reproductiveimpairment when exposed to oil. Oilhas the potential to impact spawning
success, as eggs and larvae of many shspecies, including salmon, are highly
Oiled sea otter, Prince William sound AK USFWS