Oil Spill and Its Effects On Marine Life
An oil spill is a release of liquid petroleum into the environment, especially into the ocean, coastal habitats, or soils. Oil spills create a serious threat to marine life and the environment, as they can contaminate drinking water, damage habitats, and cause extensive harm to various species. Here, we take an in-depth look at how oil spills affect marine animals.
Sources of Oil Spill
Oil spills normally occur due to a range of human activities, including offshore drilling, tankers and pipelines, oil fields, and storage facilities. Spills can also result from natural sources such as volcanic activity, tectonic plate shifts, and seeps.
Impacts of Oil Spills on Marine Life
An oil spill can cause major disruption to marine life. Oil from an oil spill spreads on the surface of the water and can coat the feathers, fur, and skin of animals living in the water. As a result, it can affect their ability to regulate body temperature, repel water, or fly. Invertebrates and mammals are particularly at risk as they rely on their fur and skin to protect themselves from predators and parasites. As such, they can become seriously ill and die if they are directly exposed to toxic oil compounds.
Unlike fur or feathers, oil doesn’t break down easily and can persist in the environment for several years. This can lead to long-term problems for marine life, including interference with their feeding and nesting habits, as well as reduced reproductive success. Some species of fish, turtles, and marine habitats won’t survive in oil-contaminated seawater. Additionally, many marine species rely on microscopic food sources that can be killed by the oil slick.
Oil spills are unfortunately a common occurrence that can have devastating impacts on marine and coastal ecosystems. Not only do they harm aquatic life directly, they can damage the environment in the long-term by contaminating the air, water, and soil. This article explains some of the physical, chemical, and biological effects of oil spills on marine life.
Physical Effects
They have a wide range of physical effects on marine life. The presence of oil can cause creatures to become entangled in the mess, damaging their skin and gills. Additionally, oil can obscure their vision and reduce their mobility when it coats and blocks gill openings and heaves. Oil, along with its unpleasant odor, can also keep animals from feeding effectively due to a lack of sense of smell and taste.
Chemical Effects
They also have a major impact on the chemical composition of the water near shore. The presence of petroleum products can cause a decrease in the dissolved oxygen levels due to the increase in bacteria that decompose the oil. This can cause fish to suffocate and die if they cannot move to areas with adequate oxygen. Oil can also produce toxic biodegradation products like nitrites, phenols, and alcohols, which are highly toxic to aquatic life.
Biological Effects
They can also disrupt the food chain structure by eliminating the populations of animals that form the base of the food web. This can cause further population decimation as species higher up in the food web, like whales and dolphins, depend on the lower levels to survive. Moreover, oil spills can lead to the spread of disease-causing microorganisms by introducing them into areas that were not previously infected.
Ways of Reducing Oil Spills
Cleaning up the spills
To help minimize the damage caused by oil spills, there are several clean-up methods available. The most common method is to remove the oil with skimmers and other mechanical devices that collect oil from the surface of the water. Oil absorbent materials, such as sawdust or synthetic booms, are also used to contain the oil and stop it from spreading further. In some cases, bioremediation can be used to reduce the toxic impact of an oil spill by introducing bacteria to break down the oil into harmless components.
Implementation of Environmental Laws
To reduce the risk of oil spills, governments and private organizations have implemented strict laws, regulations, and guidelines. Large oil companies are legally required to have emergency response plans in place to be ready to respond to any oil spill. There are also public education campaigns organized to raise awareness about the risks of oil spills and how to protect the environment from potential spills.
Oil spills can have severe impacts on marine life and the environment, contributing to wide-scale death and destruction. They have physical, chemical, and biological effects, both in the short-term and the long-term. By reducing oil use, we hope to reduce the occurrence and the impacts of oil spills on marine life.
Effects of Oil Spill on Birds, Marine Mammals, Plankton and Fishes
The effects of oil spills on marine life depend on the nature and location of the oil, and on whether it is a large or small volume spill. Even low concentrations of petroleum hydrocarbons in the marine environment may cause chronic effects on animals.
Long-term damage to biogenically structured habitats, like wetlands, reefs and seagrass beds may take years to recover.
Effects on Mammals
The most obvious effect of an oil spill is that birds and marine mammals can be oiled. The substance covers their feathers and fur, reducing their insulating capacity and making them more susceptible to temperature fluctuations. It also makes them less buoyant in water. In addition, it may interfere with their ability to eat, since it can cling to their digestive tracts and prevent them from fully ingesting their food. It can also clog their breathing passages and make it difficult to breathe. In the case of whales and dolphins that have washed ashore, it can cause them to drown.
Birds and marine mammals that forage on tidal and shallow subtidal areas, such as shorebirds, sea ducks, sandpipers, tuna, cod and shellfish, are especially at risk. These animals may be able to avoid an oil slick by diving into deeper water, but the presence of the petroleum hydrocarbons in their habitat can lead to serious consequences, including impaired reproduction, reduced weight gain and ill health.
Biological impact of oil spills depends on many factors, such as the timing and size of the spill, its proximity to shore, the depth of water in which it occurs, and weather conditions at the time of the spill. The degree of impact is also determined by how much sludge accumulates on or near the surface of the water, and how long it remains there. This is known as the “floating slick” concept, and impacts are often more severe when a large portion of the surface is covered by sludge.
The impact of an oil spill is also affected by its level of toxicity and the concentration in which it appears in the water. Oils that contain a higher percentage of petroleum hydrocarbons are more toxic than those that are lighter and less viscous. A study of the effects of the Exxon Valdez spill in 1989 on pink salmon populations showed that even small concentrations of hydrocarbons can affect survival rates and reproductive potential. However, it is often difficult to demonstrate population-level damage or recovery from a single event due to census techniques used to assess bird and marine mammal populations.
Effects on Birds
When an oil spill occurs, oiled birds often wash up on beaches. Some of these animals die of their injuries, but others are alive and well when they reach the shore. This is particularly true of the grebes, pelicans, brown pelicans and plovers that nest in marshlands. These birds may have contaminated their eggs or chicks with oil. They also may be consuming food that contains oil-related toxins.
Birds covered in oil cannot keep themselves warm or buoyant, so they need to eat. But the toxins in the oil make them ill, which can kill them. In addition, the oil can contaminate birds’ feathers and fur. The oil penetrates the feathers and fur, which makes them less insulating and more susceptible to temperature changes. It can also contaminate the birds’ nests, if they return to their colonies after feeding or bathing in contaminated water.
The type of oil matters, too. Light oils, such as gasoline and diesel fuel, evaporate quickly in the aquatic environment, so they’re not as damaging to wildlife. But heavier oils, such as those from tankers and drilling rigs, can sink to the bottom of the sea and suffocate marine life.
Another consideration is how long an oil spill lasts. For example, oil that floats for only one day can cause much less harm than an oil slick that lasts for weeks. In addition, if the oil is spread over a large area, it can contaminate more of the environment and its creatures.
Many different methods are used to estimate the number of birds affected by an oil spill. Some are based on counts of oiled birds that survive the initial assault, while others involve estimating the probability of exposure to oil by using models such as carcass sampling (van Pelt and Piatt 1995; Wiese et al. 2004; Munilla et al. 2011; Wilhelm et al. 2007; Haney et al. 2014a). However, background oiling rates can confound these estimates. One way to address this problem is to implement regular beached bird surveys, such as those conducted by the Canadian Wildlife Service and its partners.
Effects on Plankton
Oil spills are a major source of marine pollution. They can occur on the ocean and in coastal waters, from land-based sources as well, such as pipelines and tankers. The chemicals found in oil—which are the byproducts of fossil fuels—are highly toxic to wildlife that comes into contact with them or lives near polluted areas. Oil spills can have a devastating impact on marine life and on the ecosystems that depend on them. They can also devastate the economies of communities that depend on fishing and tourism.
We typically think of birds and marine mammals being harmed by oil spills, but even smaller, less-noticeable oil spills can have severe effects on marine life and the environment. The kind of oil that spills—sticky crude or bunker fuel or non-sticky refined petroleum products—may affect different kinds of marine life differently. Whether the oil lasts long enough to linger on animals may also make a difference. Some oils dissolve very quickly, allowing the animal to get rid of it before it has a chance to cause harm; other oils stick to the skin or fur of animals or the feathers of birds.
Aside from direct contact with oil, some species of marine life may be harmed by the oxygen-depleting effects of an oil slick on the water surface. This is especially true for species living in shallower waters, where the oil slick blocks sunlight and prevents photosynthesis and other vital processes.
Some of the thicker oil sinks to the bottom of the sea and can be ingested by rockfish and white croakers, posing a risk to these species as well as humans who eat them. The oil also contaminates the sediments, killing coral and making them unsafe for other marine organisms to live in.
It is important to remember that it can take a long time for marine species to recover from the effects of an oil spill, as the damage may last for years. However, NOAA experts work to evaluate the impacts of oil spills and design restoration projects to help the ocean recover. These can include projects like building marshland and protecting bird nesting habitat, and are often more effective than just cleaning up the mess.
Effects on Fish
An oil spill may have a variety of sublethal effects on fish. The toxic components of crude oil can kill fish that come into direct contact with the liquid or dispersant, and lingering petroleum residues can interfere with natural chemical processes that affect survival, growth, reproduction and other vital functions. Several studies have found that populations of fish are reduced by the presence of even relatively low concentrations of oil.
Young fish and other species are particularly vulnerable to oil. They often live in shallow coastal waters and are more likely to be exposed to the surface of a slick than adult fish. Moreover, they are more likely to be in early life stages such as embryonic or postembryonic, when exposure to high concentrations of contaminants can have severe effects.
Aside from direct contact with oil, many fish and shellfish will become affected through the ingestion of contaminated food or a combination of indirect and direct exposure to oil. This may lead to reduced reproductive success and lowered chances for survival, and it can also cause physical harm such as altered heart or respiratory rates.
The extent of these impacts depends on a number of factors, including the nature of the spill and its location. Oil that forms large slicks on the surface of the water tends to have greater effects than oil that pools on the bottom of the sea. In addition, the timing of the spill is important. If it happens when birds are aggregated during breeding or migration, the impact will be much greater than if it occurs at other times of year.
It is also difficult to predict the long-term effects of a spill on fish and other marine organisms. This is especially true for populations that are highly specialized or occur in a very narrow ecological niche. It can take time for a fish or shellfish to recover from a lethal dose of oil.
In the meantime, workers and businesses that depend on fishing will suffer a loss of income. Affected regions may also be shut off from shipping routes, further depriving local economies of their traditional source of income.
