Marine Defender: Dr. John Stegeman
Woods Hole Oceanographic institute
ResEArching oil impacts on deep water fish
Dr. John Stegeman, the director of the Woods Hole Center for Oceans and Human Health in Massachusetts, collects deep-sea fish from the middle of the Atlantic Ocean, a region once thought to be one of the purest on earth.
When oil is no longer visible in the water, many assume that it is no longer a problem. However, environmental toxicologists like Dr. Stegeman now know that this is not the case. Oil dissolved in water can be dangerous for fish, whales, sea turtles, and other wildlife, even in tiny amounts.
How do researchers know if a marine animal has been exposed to oil?
Some of the research on the effects of oil pollution in the water is carried out by studying a protein called Cytochrome P4501A (CYP1A).
When a fish comes into contact with oil, some of the most toxic parts of oil (known as polycyclic aromatic hydrocarbons, or PAHs) enter the bloodstream after being inhaled or absorbed through the skin. Once these PAHs are inside of the fish, they set off its cellular defenses.
PAHs are recognized by receptors in the cell (known as aryl hydrocarbon receptors), which cause the cell’s defenses to leap into action and begin the production of CYP1A in an attempt to render the PAHs harmless. Unfortunately, sometimes PAHs are not neutralized by CYPIA and become even more toxic as a result of the cell’s attempts at self-defense.
CYP1A, explains Dr. Stegeman, acts as a biological fingerprint that indicates if an organism has been exposed to the PAH's in oil. It's a unique bio-marker that “lights up” when a marine organism is exposed to the toxins in oil, causing "a cascade of cellular effects" which influence which genes are “turned on” in the DNA.
When a fish has been exposed to PAHs, the gene that produces CYP1A remains lit up, and its activation can be seen under a special microscope. This process creates a visible genetic trail that scientists can use to track exposure to oil pollution. And they are learning that the results of these genetic changes may be linked to reduced fertility, growth rates, and increasing susceptibility to cancer.
Sadly, Dr. Stegeman’s research shows that even fish living deep in the middle of the ocean in what should be one of the cleanest areas on earth are now displaying signs of exposure to the toxins in oil.