The Environmental Effects of Marine Oil Spill (The Niger Delta Oil Spill Effects)



The environmental effects of marine oil spills, wherever they happen, may include the effects to wildlife. The immediate impact of an oil spill on marine wildlife such as marine and coastal birds, marine mammals and marine reptiles (e.g. turtles) may be considerable. If in the middle of an area where vulnerable species are abundant, the spill may victimise tens to hundreds or even thousands of animals, especially birds in Europe. The long term impact of an oil spill depends on the proportion of the breeding population of any species that gets affected.

The impact of an oil spill on marine animals can be reduced by taking timely and effective measures as part of the overall oil spill response. At different stages of the response, including a pre-incident phase of contingency planning, there are specific response options that can be considered to prevent wildlife from oiling or to reduce the effects of oiling. An integrated oiled wildlife response requires specific knowledge, strategies and techniques in order to be effective and successful.

1.1 Historical Background

Europe has an impressive history of oiled wildlife experiences including incidents that go back as far as 1967 and including e.g. Torrey Canyon (UK, 1967), Amoco Cadiz (France, 1978), Braer (UK, 1993), Sea Empress (UK, 1996), Pallas (Germany, 1998), Erika (France, 1999) and the more recent incidents such as Prestige (Spain, 2002), Tricolor (France/Belgium, 2003), Fu Shan Hai (Denmark, 2003), Rocknes (Norway 2004), Glomma river spill (Norway, 2006), Server (Norway, 2007), Duncan Island (Germany, 2008) and a number of so called mystery spills (Estonia, 2006; Germany, 2001, 2004 and 2008) and presently in Niger-Delta.

National authorities in an increasing number of European countries have become interested in exploring the needs and options for oiled wildlife response planning, recently stimulated by a series of three EU workshops in 2006 and the outcome of the related projects (Anon. 2007a). Agreed plans already exist in France, the UK and Belgium. In other countries, e.g. Netherlands, Germany plans are being developed and in a number of other countries national discussions, involving authorities, wildlife responders and sometimes industry, have started. Recently the Baltic Sea States have decided to add oiled wildlife preparedness and response to their programme of international cooperation under the Helsinki Convention (Helcom, 2007a; 2007b).

The emerging field of oiled wildlife preparedness and response in Europe clearly comes with a range of new challenges for many stakeholders. Many of these challenges are best dealt with at an international level, because they are basically the same in any country. Discussions so far have already resulted in the publication of a range of international guidelines on good practice, international strategies and centralised information sources (IPIECA, 2004; Anon., 2007a, 2007b, 2007c, Camphuysen, 2007). 

1.2    The Term OIL

The Term Oil describes a broad range of hydrocarbon- based substances. Hydrocarbons are chemical compounds composed of the elements hydrogen and carbon. This includes substances that are commonly thought of as oils, such as crude oil and refined petroleum products, but it also includes animal fats, vegetable oils, and other non- petroleum oils. Each type of oil has distinct physical and chemical properties. These properties affect the way oil will spread and break down, the hazard it may pose to aquatic and human life, and the likelihood that it will pose a threat to natural and man-made resources.

The rate at which an oil spill spreads will determine its effect on the environment. Most oils tend to spread horizontally into a smooth and slippery surface, called a slick, on top of the water. Factors which affect the ability of an oil spill to spread include surface tension, specific gravity, and viscosity. Surface tension is the measure of attraction between the surface molecules of a liquid. The higher the oil’s surface tension, the more likely a spill will remain in place. If the surface tension of the oil is low, the oil will spread even without help from wind and water currents. Because increased temperatures can reduce a liquid’s surface tension, oil is more likely to spread in warmer waters than in very cold waters. Specific gravity is the density of a substance compared to the density of water. Since most oils are lighter than water, they float on top of it. However, the specific gravity of an oil spill can increase if the lighter substances within the oil evaporate. Heavier oils, vegetable oils, and animal fats may sink and form tar balls or may interact with rocks or sediments on the bottom of the water body. Viscosity is the measure of a liquid’s resistance to flow. The higher the viscosity of the oil, the greater the tendency for it to stay in one place. (Honey is an example of a highly viscous liquid.)

1.3 The Fate of Spilled Oil

Natural Actions are always at work in aquatic environments. These can reduce the severity of an oil spill and accelerate the recovery of an affected area. Some natural actions include weathering, evaporation, oxidation, biodegradation, and emulsification. Weathering is a series of chemical and physical changes that cause spilled oil to break down and become heavier than water. Wave action may result in natural dispersion, breaking a slick into droplets which are then distributed vertically throughout the water column. These droplets can also form a secondary slick or thin film on the surface of the water. Evaporation occurs when the lighter or more volatile substances within the oil mixture become vapours and leave the surface of the water. This process leaves behind the heavier components of the oil, which may undergo further weathering or may sink to the bottom of the ocean floor. Spills of lighter refined products, such as kerosene and gasoline, contain a high proportion of flammable components known as light ends. These may evaporate within a few hours, causing minimal harm to the aquatic environment. Heavier oils, vegetable oils, and animal fats leave a thicker, more viscous residue. These types of oils are less likely to evaporate. 

1.4 Effect of Oil Spillage on Plants and Animals

Some Toxic Substances in an oil spill may evaporate quickly. Therefore, plant, animal, and human exposure to the most toxic substances are reduced with time, and are usually limited to the initial spill area. Although some organisms may be seriously injured or killed very soon after contact with the oil in a spill, non- lethal toxic effects can be more subtle and often longer lasting. For example, aquatic life on reefs and shorelines is at risk of being smothered by oil that washes ashore. It can also be poisoned slowly by long-term exposure to oil trapped in shallow water or on beaches. Both petroleum and non-petroleum oil can affect the environment surrounding an oil spill. All types of oil share chemical and physical properties that produce similar effects on the environment. In some cases, non-petroleum oil spills can produce more harmful effects than petroleum oil spills.

1.5 Aquatic Environments

Aquatic environments are made up of complex interrelations between plant and animal species and their physical environment. Harm to the physical environment will often lead to harm for one or more species in a food chain, which may lead to damage for other species further up the chain. Where an organism spends most of its time—in open water, near coastal areas, or on the shoreline—will determine the effects an oil spill is likely to have on that organism.

In open water, fish and whales have the ability to swim away from a spill by going deeper in the water or further out to sea, reducing the likelihood that they will be harmed by even a major spill. Aquatic animals that generally live closer to shore, such as turtles, seals, and dolphins, risk contamination by oil that washes onto beaches or by consuming oil-contaminated prey. In shallow waters, oil may harm sea grasses and kelp beds, which are used for food, shelter, and nesting sites by many different species.

Spilled oil and clean-up operations can threaten different types of aquatic habitats, with different results.

Coral reefs are important nurseries for shrimp, fish, and other animals as well as recreational attractions for divers. Coral reefs and the aquatic organisms that live within and around them are at risk from exposure to the toxic substances within oil as well as smothering. Exposed sandy, gravel, or cobble beaches are usually cleaned by manual techniques. Although oil can soak into sand and gravel, few organisms live full-time in this habitat, so the risk to animal life or the food chain is less than in other habitats, such as tidal flats.

1.6 Niger Delta Oil Spill Effect

Since the discovery of crude oil at Oloibiri, Nigeria, the oil industry in Nigeria has completely restructured the country’s economy. Prior to 1958, Nigeria’s economy relied on the production and export of cocoa, palm oil and kernels, timber, rubber, cotton, and groundnuts (Freund, 1978).

Furthermore, according to the United Nations Development Programme, in Nigeria (2006), prior to World War II, “a delicate balance existed between the human populations of the Niger Delta and its fragile ecosystem. The exploitation of natural resources did not go beyond the search for medicinal herbs, fuel, game, fish, and construction materials. Today, the oil and gas sector contributes 79.5% of the government’s revenues and is responsible for 97% of Nigeria’s foreign exchange revenues (Amnesty International, 2009).  The Shell Petroleum Development Company (SPDC), a subsidiary of Royal Dutch Shell is the largest operator in the region.

The SPDC is a joint venture between the Nigerian National Petroleum Corporation (NNPC) at 55% ownership, Shell at 30%, Elf Petroleum Nigeria Ltd. at 10%, and Agip at 5% ownership. The Niger Delta covers approximately 70,000km2 and is home to over 40 ethnic groups. The SPDC alone prospects on over 40% of this land and operates pipelines, wells, and flow stations that often exist near homes, farms, and communities. Hundreds of thousands of these people are affected by the resulting oil contamination near their homes. Especially affected are some 60 percent of the region’s inhabitants who have little money and rely on fishing and agriculture to survive (UNDP, 2006). In the Niger delta, oil spills are a common occurrence.

Reasons for spills include corrosion of pipelines, poor maintenance of infrastructure, spills or leaks during processing at refineries, human error, and as a consequence of intentional vandalism or theft of oil (Amnesty International, 2009). The UNDP (2006) estimates that between 1976 and 2001 there were approximately 6,800 spills totalling 3,000,000 barrels of oil. This value represents only the data that oil companies chose to report to the Department of Petroleum Resources (DPR), thus the data provided by the companies and reported by the DPR do not accurately represent the magnitude of the oil spillage. Because of this potentially inaccurate data, an independent group of experts on oil and the environment endeavoured to establish their own estimation of total oil spilled before 2007 (Jernelöv, 2010). By considering all sources of oil discharge into the environment, the group estimated a total discharge between 9 and 13 million barrels over 50 years. This roughly translates to 1.5 million tons or one Exxon-Valdez spill annually for half a century.

The severity of these frequent and collectively massive spills is only amplified by other environmental problems in the region. In particular, the region is plagued with seasonal floods and has a shortage of land for development (UNDP, 2006). This means that contaminated water and sediment is spread all over “communities, roads, and farmlands which are partially or totally submerged”. In the case of a serious spill, people may not even be able to relocate due to the shortage of land for development.


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