Even trace amounts of pollution may cause biological harm, says a new study published in the Proceedings of the National Academy of Sciences. Researchers investigating the effects of the 2010 Gulf oil spill on killifish, a key food species preyed on by the economically important red snapper, found that even in locations where the oil had mostly dissolved, the fish still felt the effects.
The researchers looked at a set of killifish genes whose is expression is known to be altered by environmental polychlorinated biphenyls (PCBs), pollutants from plasticizers and flame retardants that are associated with endocrine disruption. Such gene expression changes are linked to abnormal development and lowered reproductive success. Using water and fish samples collected in the first four months of the spill, the researchers found that the polycyclic aromatic hydrocarbons found in crude oil can similarly alter gene expression: killifish from areas near the oil spill, even those that avoided an oil slick, showed gene changes similar to killifish embryos treated in the lab with hydrocarbon-contaminated water from the same sites.
"It's striking that even though the analytical chemistry doesn't indicate exposure, the biology does," Andrew Whitehead, a biologist at Louisiana State University in Baton Rouge, who led the study, told Nature ."We can measure all the chemistry we want in the environment, but if want to know whether organisms have been exposed, we have to ask them."