Last week, Our Habitat began a look at oil and its effects on the environment through an examination of some of the world’s major producers of oil, how oil behaves and how oil pollution happens. We look this week at the impact oil has on living resources.

OIL may affect living resources by causing immediate death due to coating or through the effect of toxic components.

Immediate death is referred to as lethal effect, and occurs because the oil or its components interfere with cellular processes, resulting in cell death.

Sometimes death does not occur immediately, but the organism may be affected by changes in its physiological processes or behaviour patterns that eventually lead to death. This is referred to as a sub-lethal effect.

Whether effects are lethal or sub-lethal depends on the type of environment, the type of oil (crude or relined), the organism, the stage of life cycle of the organism and the level of exposure.

Organisms/resources affected

Oil can severely damage plants, with the most affected species being salt marshes and mangroves because of their habitat’s location in the coastal environment.

Oil may kill plants or stop their future growth by forming a physical barrier, coating the leaves and stems, which prevents the exchange of gases, such as oxygen and carbon dioxide. It may also be directly toxic; contaminate soil and affect soil properties; or affect the ability of surrounding plants to grow.

Animals, being mobile, may fare better than plants.

However, their mobility may lead to them getting contaminated if they are unaware of the contaminated area of their environment.

Groups that are most affected by oil spills include marine mammals, such as manatees, whales and dolphins. Marine mammals that swim through a slick may be damaged as a result of oil coating the skin, getting in the eyes, or being ingested.

Birds and fish are no exceptions

Birds are also at risk, with the most common form of damage being to the plumage, which provides them with natural insulation and waterproofing.

Oil may cause the plumage to become matted, allowing water to enter spaces between the feathers and the skin. The birds then lose their buoyancy, and may sink and drown. An attempt to clean the feathers by preening can lead to ingestion of the oil, which may result in death.

The surfaces of most fish are coated with a mucus to which oil does not readily stick, but the use of dispersants can destroy this protective coating. Fish are sometimes affected by the toxic components, which dissolve in the water or by oil clogging the gills.

Sea turtles may be affected by swimming through oil, or by a slick preventing them access to a beach on which they lay their eggs.

In addition to the effects on individual groups of organisms, the effects of oil may be felt on various habitats, such as the open sea, the sea bed, coral reefs, intertidal rocks, mud flats, salt marshes, mangrove swamps, as well as freshwater and terrestrial habitats.

Dr Margaret Jones-Williams is a director and principal consultant at Environmental Solutions Ltd (ESL), an environmental management services company with its main office in Kingston, Jamaica.

We look next week at some of the things we can do to prevent oil pollution and its damaging effects on the environment.