Voyager: Will the Gulf of Mexico Oil Spill Cause Mutations?

Q. Will the aftermath of the Gulf of Mexico oil spill involve all sorts of mutations or new species of sea life?

– Submitted by Marisa G., 15, Alpha, N.J.

Scientists do not expect to see lots of new mutations or new species of sea life as a result of the gulf oil spill. Crude oil is a complex mixture of compounds that has a wide range of effects on marine organisms. Some components of crude oil are quite toxic to specific organisms so immediate impacts can be seen in high death rates in some species. However, the vast dilution of the oil and chemical dispersants in the surrounding seawater means that most organisms are exposed to only low concentrations of the toxins and survive fairly unharmed.

How does long-term, low-level exposure to oil impact marine organisms? Due of the diversity of the compounds involved and the even greater diversity of organisms exposed, this is not an easy question to answer.

When contaminants such as oil enter the cells of organisms, they can interfere with the intricate molecular machinery involved in normal function. For example, the development process from a simple fertilized egg to a complex adult organism is quite susceptible to chemical toxins. Even low levels of exposure to some chemicals can lead to developmental abnormalities including physical deformities. It is important to distinguish between problems caused by chemical interference with normal developmental processes and mutations that could lead to new species of marine life.

Mutations are structural changes to DNA that are transmitted from parent to offspring. Mutations are occurring all the time in the natural environment, resulting from many causes, including exposure to the sun’s UV radiation, chemicals in the environment, and random errors from imperfect DNA replication. Exposure to oil may result in a slightly higher than normal mutation rate, but available data do not suggest this would be very significant. Most mutations are repaired by the cell’s own DNA repair machinery. Mutations that lead to dramatic physical changes in an individual organism typically result in the inability to reproduce; so new species are not easily established from pollution events.

In most cases of chemical pollution, if you see an affected animal with a physical deformity, it is more likely due to interference with development than mutation. Developmental problems are not transmitted to the offspring, so no new life forms would result.

– Ron Burton, director, Marine Biology Research Division

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