Oil slicks cause heartaches in fish.
Incardona JP, MG Carls, HL Day, CA Sloan, JL Bolton, TK Collier and NL Scholz. 2008. Cardiac arrhythmia is the primary response of embryonic pacific herring (Clupea pallasi) exposed to crude oil during weathering. Environmental Science and Technology 10.1021/es802270t.
The findings show that impaired heart function is one of the earliest disease effects of oil exposure. Heart damage may be the major mechanism by which crude oils - and their harmful polycyclic aromatic hydrocarbons (PAHs) - affect fish populations.
In prior studies and real world observations, other types of fish embryos that have been exposed to crude oil develop a cluster of similar health problems later in life, including yolk sac edema and small jaws. These conditions often worsen in fish populations exposed to spilled oil that has aged (called weathered), exposing them to the more harmful types of PAHs released from the weathered crude.
Thousands of oil spills pollute fresh and marine water every year. Wildlife, endangered species, food fisheries and sport fishing are at risk from the disasters.
In this laboratory study, government scientists exposed fish (Pacific herring) embryos to various levels of weathered crude oils. They found that as the dose of the crude oil increased, the fish's heart function decreased. The changes in heart rate and heart rhythm started as soon as the fish established a regular heart beat, about 5 days after fertilization.