External Effects of Oil Spills on Marine Organisms

Once oil has been exposed to marine environments, the oil spreads rapidly, coating the surface waters with the aid of wind and currents: "A single gallon of oil can create an oil slick up to a couple of acres in size!" (Effects of oil spills). Over time, when the oil and the water begin to mix, the oil begins to weather, creating a "mousse", which is a sticky, oily substance that attaches to "whatever it comes in contact with" (Effects of oil spills). This "mousse" is extremely harmful to marine organisms, having both internal and external effects. Many marine organisms are incapable of escaping such oil slicks, not knowing how to avoid them, and many fish are, actually, attracted to them because they "can resemble food" (Effects of oil spills). (Effects of oil spills) 


Following a marine oil spill, the oil in the marine habitats coats the bodies of marine organisms with a thick layer of oil. This oil only becomes stickier over time. Because oil and water do not mix immediately once an oil spill occurs and coats the surface of the water, marine mammals and birds are targets of the harmful effects of oil spills. Seals, dolphins, and other marine mammals "have been seen swimming and feeding in or near an oil spill" (Effects of Oil on Wildlife). The fish that are attracted and lured to the oil spills that resemble food are prey to the sea birds who dive through the oil slicks in an attempt capture their prey. (Effects of Oil on Wildlife) 


Once the sticky, weathered oil, usually crude or bunker oil fuels, has attached itself to the fur and feathers of the marine organisms, many harmful effects to the marine organisms are the results. Many sea birds are susceptible to hypothermia because the oil can reduce or destroy "the insulation and waterproofing properties of their feathers" (Effects of Oil on Wildlife). Similarly, hypothermia is also a threat to fur seal pups because the oil can also reduce or destroy the insulation of their woolly fur. In addition, sea birds are prone to sinking and drowning when they come in contact with oil because "oiled feathers weigh more, and their sticky feathers cannot trap enough air between them to keep them buoyant" (Effects of Oil on Wildlife). Also, it is a possibility that seal pups will drown because the oil cam stick their flippers to their bodies. Many marine mammals lose much body weight because "they can not feed due to contamination of their environment by oil" (Effects of Oil on Wildlife). These are just some of the harmful, and, sometimes, fatal, effects of oil spills on marine organisms. (Effects of Oil on Wildlife) 




Sources: 
Effects of oil spills: <http://www.greenlivingtips.com/blogs/164/Effects-of-oil-spills.html> 
Effects of Oil on Wildlife: <http://www.amsa.gov.au/marine_environment_protection/educational_resources_and_information/teachers/the_effects_of_oil_on_wildlife.asp>  

Introduction to Marine Oil Spills

706 million gallons: the amount of waste oil that enters the marine environment per year. Oil can enter the oceans through many different passages, but the majority of oil that enters the ocean originates from "land based sources and from unregulated recreational boating" (Oil Spills: Impact on the Ocean). Other forms of oil entering the marine environment include drainage of storm water that contains components of oil and improper treatment of waste disposal. Tanker crashes and other transportation accidents accommodate for 5.2% of oil that exists in the oceans, routine repairs and maintenance of ships make up 20%, and 13% of the oil within the oceans come from "hydrogen particles from online air pollution", and 8% is due to the natural uplifting of oil from the ocean floor (Oil Spills: Impact on the Ocean).

The gravity of marine oil spills relies on many factors. Factors that influence the severity of marine oil spills include "the type and quantity of oil spilled, the season and weather, the type of shoreline, and the type of waves and tidal energy in the area of the spill" (Effects of Oil Spills on Wildlife and Habitat). Because the density of oil is less than 1g/mL (the density of water), oil floats on the surface of the ocean and coats the water as a sheen. The intensity of waves, currents, and winds can expand the coverage of oil to larger areas in the marine environment. 

The way oil affects the environment physically, chemically, and biologically is called weathering, and weathering can actually reduce the harmful toxins in oil over time. Other forms that diminish oil from the marine environment include evaporation, decomposition by sunlight (photolysis), and decomposition by microorganisms (biodegradation). Biodegradation relies on the availability of nutrients and oxygen, the type of microorganism, and the temperature.  In addition, small amounts of waste oil dissolve in the ocean waters. 

Sources: 

http://alaska.fws.gov/media/unalaska/Oil%20Spill%20Fact%20Sheet.pdf

http://www.waterencyclopedia.com/Oc-Po/Oil-Spills-Impact-on-the-Ocean.html