**Impact of Oil Spills on Marine Life**

## Ismail M.K. Saadoun

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/60455

#### **Abstract**

Petroleum contamination is a growing environmental concern that harms both terrestrial and aquatic ecosystems. However, the public and regulatory and scientific communities have given more attention to the contamination of marine habitats. This is because marine oil spills can have a serious economic impact on coastal activities, as well as on those who exploit the resources of the sea. Thus, communities that are at risk of oil disasters must anticipate the consequences and prepare for them.

The deliberate release of around 6 million barrels of oil during the 1991 Gulf War in the marine environment is the largest oil spill in history. In the Gulf of Mexico, the BP Deepwater Horizon (DWH) oil spill on 20th April, 2010, which lasted over approxi‐ mately three months, is the second largest in human history.

When oil is spilled at sea it initially spreads out and moves on the water surface as a slick. It is a few millimetres thick and moves with the wind and current. At the same time, it undergoes a number of chemical and physical changes. The spreading of marine oil spills is affected by the action of winds, waves, water currents, oil type and temperature. Marine oil spills enhance the evaporation of volatile fractions such as low molecular weight alkanes and monoaromatic hydrocarbons. The natural actions, which are always at work in aquatic environment, include weathering, evaporation, oxidation, biodegradation and emulsification.

Generally, the effects of oil toxicity depend on a multitude of factors. These include the oil composition and characteristics (physical and chemical), condition (i.e., weathered or not), exposure routes and regimen, and bioavailability of the oil. If the levels exceed the threshold concentration, the additive toxic effect of hydrocarbons can lead to mortality. PAHs are the major contributors to toxicity. They have different metabolic pathways that produce metabolites. These have oxidative and carcinogenic properties due to their ability to attack and bind to DNA and proteins. Inhaling

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hydrocarbons can cause respiratory tract irritations, as well as narcosis in mammals and birds. This is due to the volatile nature of hydrocarbons. Oil dispersants, which are a common tool used after oil spills, are also toxic and threaten pelagic and benthic organisms, as well as fish.

In recent years, written studies have provided a considerable amount of information regarding the impact of oil spills and contamination of the seawater by hydrocarbons. The impact on marine life is impaired by the toxicity and tainting effects resulting from the chemical composition of oil, as well as by the diversity and variability of biological systems and their sensitivity to oil pollution. Marine life may also be affected by clean-up operations or, indirectly, by the physical damage to the habitats in which plants and animals live.

Communities that are threatened by marine oil spills have developed their own plans and policies to counteract the risk of marine oil contamination. These range from permitting or prohibiting increased oil transport volumes, to developing the capacity to respond to and recover from potential oil spill disasters. Considering that approx‐ imately half of the world's oil production comes from the Gulf States and passes through the Gulf, its liability to pollution is about 48 times that of any other similar area on earth. Thus, the Gulf is possibly the most chronically oil-polluted marine area in the world. Due to the different anthropogenic activities relating to oil spills, in addition to the natural environmental stresses of the Gulf, a number of socio-economic impacts are predicted. The multi-million dollar fish industry will be threatened, as well as the desalination of plants that supply most of the Gulf population's freshwater. Furthermore, people with careers in scuba diving will lose their jobs. As a result, the scuba diving tourism sector will also come under threat.

**Keywords:** Contamination, Crude, Hydrocarbon, Impact, Life, Marine, Oil, Petrole‐ um, Spill, Toxicity, Water

#### **1. Introduction**

Environmental pollution caused by petroleum is of great concern. This is because petroleum hydrocarbons are toxic to all forms of life and harm both aquatic and terrestrial ecosystems. The pollution of marine habitats has caught the attention of researchers and environmentalists. This is due to the serious impact of oil spills on marine life, as well as on people whose career relies on the exploitation of the sea's resources. Additionally, marine life may be affected by clean-up operations. It may also be indirectly affected by the physical damage to the habitats in which plants and animals live in.

Petroleum marine fuel spills, which result from damage, transportation accidents and vari‐ ous other industrial and mining activities, are classified as hazardous waste [1]. They are considered to be the most frequent organic pollutants of aquatic ecosystems [2-3].

In recent years, there have been numerous studies regarding the levels of contamination of the seawater by hydrocarbons. The majority of these studies were conducted following the Gulf War of 1991 [4-11] and after, the BP Deepwater Horizon (DWH) oil spill on 20th April, 2010 [12-14].

In the current manuscript, we discuss the effects of petroleum oil spills on marine life. It incorporates different sections that outline the major petroleum oil spills associated with the marine environment, chemical composition of crude oil, toxicity of oil and oil dispersants. We discuss the major petroleum oil spills associated with the chemical and physical states of crude oil and their impact on microbial, plant and animal marine life. We also consider the economic impact of oil spills on coastal activities and on the people who exploit the resources of the sea.
